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Hindawi Publishing Corporation Mathematical Problems in Engineering Volume 2013, Article ID 406018, 5 pages http://dx.doi.org/10.1155/2013/406018 Research Article Analysis on Nonlinear Stress-Growth Data for Shear Flow of Starch Material with Shear Process Jinghu Yu, Dejun Ma, and Hui Lu Jiangnan University, Lihu Road No. 1800, Wuxi, Jiangsu, China Correspondence should be addressed to Jinghu Yu; [email protected] Received 3 May 2013; Accepted 29 May 2013 Academic Editor: Jun Wang Copyright © 2013 Jinghu Yu et al. is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. e material function of liquid materials for packaging plays an important role in analysis of its mechanical behavior. e mechanical behavior of material affects the packaging process in many aspects, such as selection of packaging materials and preparation of packaging method. erefore, research on the material function of the liquid material is very helpful to guide the packaging process and look into how the packaging quality and efficiency are affected by the mechanical properties of material. is paper established the material function for the starch solution under shear process. With the relaxation test of the starch solution specimens, the () function and dumping function were established and verified. Based on the memory function of starch solution, the material function of starch solution was constructed and approved to be efficiently predict the mechanical behavior during the shear process. erefore, such material function can be used to guide the operation on the shear flow. 1. Introduction Starches have been used for many years in the food industry, and their rheological properties decide different applications in food products [1, 2]. For this reason, their rheological behavior has deserved increasing attention. e nonlinear behavior of starch solution plays an important role in many packaging processes, and especially it affects the packaging material transmission speed and high weight measurement precision [3, 4]. Analysis of the nonlinear viscoelastic behav- ior of starch solution is of great importance for their rheolog- ical characterization. e material function is the basis of the analysis on the starch solution. In order to establish its material function, the constitutive equation must be constructed according to the most suitable experiment [5]. It is oſten found that the Lodge model can successfully describe the behavior of rubber-like liquid under shear flow or elongational flow [6, 7]. e Lodge model can be expressed as follows: () = − ∫ −∞ ( − , ) ∗ ( ) , (1) where is the stress at the current time , ( − , ) is the memory function specific for the material, and it can be established by suitable experiment. ( ) is the strain function dependent on the time t, and it can be defined in the specific process. Recently, the memory function is oſten expressed as a product of the memory function for the linear behavior () and a so-called damping function ℎ() [810]. Yu et al. [11] established and validated a rheological model that can be used to characterize viscoelastic properties of food gels during compression under small and large deformation [11]. e aim of this paper is to give experimental justification for linear behavior () and the damping function ℎ(). Taking the starch solution as sample, its material function was established based on the linear shear modulus () and damping function ℎ(). rough comparison of the experimental data and the calculated shear stress by the material function, the material function of starch solution was approved to be successfully describing the behavior of the starch solution under shear flow. 2. Experimental Materials and Methods e type of modified starch is ULTRA-TEX 1 corn starch from National Starch Food Innovation. is kind of starch
Transcript
Page 1: Research Article Analysis on Nonlinear Stress-Growth Data ...

Hindawi Publishing CorporationMathematical Problems in EngineeringVolume 2013 Article ID 406018 5 pageshttpdxdoiorg1011552013406018

Research ArticleAnalysis on Nonlinear Stress-Growth Data for Shear Flow ofStarch Material with Shear Process

Jinghu Yu Dejun Ma and Hui Lu

Jiangnan University Lihu Road No 1800 Wuxi Jiangsu China

Correspondence should be addressed to Jinghu Yu jhyujiangnaneducn

Received 3 May 2013 Accepted 29 May 2013

Academic Editor Jun Wang

Copyright copy 2013 Jinghu Yu et alThis is an open access article distributed under theCreativeCommonsAttribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The material function of liquid materials for packaging plays an important role in analysis of its mechanical behavior Themechanical behavior of material affects the packaging process in many aspects such as selection of packaging materials andpreparation of packaging method Therefore research on the material function of the liquid material is very helpful to guide thepackaging process and look into how the packaging quality and efficiency are affected by themechanical properties of materialThispaper established the material function for the starch solution under shear process With the relaxation test of the starch solutionspecimens the119866(119905) function and dumping functionwere established and verified Based on thememory function of starch solutionthe material function of starch solution was constructed and approved to be efficiently predict the mechanical behavior during theshear process Therefore such material function can be used to guide the operation on the shear flow

1 Introduction

Starches have been used for many years in the food industryand their rheological properties decide different applicationsin food products [1 2] For this reason their rheologicalbehavior has deserved increasing attention The nonlinearbehavior of starch solution plays an important role in manypackaging processes and especially it affects the packagingmaterial transmission speed and high weight measurementprecision [3 4] Analysis of the nonlinear viscoelastic behav-ior of starch solution is of great importance for their rheolog-ical characterization

The material function is the basis of the analysis on thestarch solution In order to establish its material function theconstitutive equation must be constructed according to themost suitable experiment [5] It is often found that the Lodgemodel can successfully describe the behavior of rubber-likeliquid under shear flow or elongational flow [6 7]The Lodgemodel can be expressed as follows

120590 (119905) = minusint

119905

minusinfin

119872(119905 minus 1199051015840 120574) lowast 120576 (119905

1015840) 1198891199051015840 (1)

where 120590 is the stress at the current time 119905 119872(119905 minus 1199051015840 120574) isthe memory function specific for the material and it can be

established by suitable experiment 120576(1199051015840) is the strain functiondependent on the time t and it can be defined in the specificprocess

Recently the memory function is often expressed as aproduct of the memory function for the linear behavior119866(119905) and a so-called damping function ℎ(120574) [8ndash10] Yu et al[11] established and validated a rheological model that canbe used to characterize viscoelastic properties of food gelsduring compression under small and large deformation [11]The aim of this paper is to give experimental justificationfor linear behavior 119866(119905) and the damping function ℎ(120574)Taking the starch solution as sample its material functionwas established based on the linear shear modulus 119866(119905)and damping function ℎ(120574) Through comparison of theexperimental data and the calculated shear stress by thematerial function the material function of starch solutionwas approved to be successfully describing the behavior of thestarch solution under shear flow

2 Experimental Materials and Methods

The type of modified starch is ULTRA-TEX 1 corn starchfrom National Starch Food Innovation This kind of starch

2 Mathematical Problems in Engineering

7 starch solution

Strain sweep from 00001 to 10 strain sweep step

Strain ()

0101001

1

11

10

10

10

100

01

1

10

100

100 1000 10000

100

G998400

(Pa)

G998400998400

(Pa)

120575(d

egre

es)

Figure 1 Strain sweep test from 00001 to 10 at the frequency 1

7 starch solution

Strain is 03 stress relaxation test

Time (s)

1

10

100

1000

10000

1E5

Mod

ulus

G(t)

(Pa)

0 50 100 150 200 250 300

Figure 2 Relaxation test within linear range of strain

and distilled water were used tomake different concentrationstarch solution The whole experiment was performed onthe Rheometer AR-2000 from TA instruments Ltd The conehead was installed and its angle is 28 degree The constanttest temperature is 25∘C

High shear rate and long time shear test were performedto find if the shear process affects the strain relaxation testShear rate influence on the strain can be found Thereforethememory function can be established by themany differentstrain relaxation tests

3 Memory Function for the NonlinearViscoelastic Behavior

Thememory function can characterize the mechanical prop-erty of the specific material [12] According toWagner [9 10]

for simple shear flow the generalized memory function isexpressed by

119872(119905 minus 1199051015840 1205741199051199051015840) =sdot

119872 (119905 minus 1199051015840) ℎ (1205741199051199051015840) (2)

wheresdot

119872 (119905minus1199051015840) is the linearmodulus ofmaterial under small

deformation It describes the linear relationship betweenthe strain and stress of material The nonlinearity of therheological behavior is only characterized by the dumpingfunction ℎ(120574

1199051199051015840)

For simple shear flow the well known relations for theshear stress 120590(119905) can be expressed by

120590 (119905) = int

infin

0

119872(119905 minus 1199051015840) 12057411990511990510158401198891199051015840 (3)

In order to establish the shear modulus function and thedamping function the linear range of the relationship of thestress and strainmust be foundwith strain sweep test Figure 1shows that the storage modulus1198661015840 the lost modulus 11986610158401015840 anddifferent degree delta are almost constant when the strain isless than 001 It indicates that the relationship of stress andstrain of starch solution is linear during the step in shearstrain from0 to 001Therefore in the linear viscoelastic rangethe shear relaxation modulus 119866(119905) can be given by

119866 (119905) asymp 119866 (119905 120574) =120590 (119905)

120574 (4)

According to the strain sweep test result the suitablestrain relaxation test was carried out The measurement dataof relaxation test was shown in Figure 2 The strain value ofrelaxation test is 03 and it belongs to the linear viscoelasticrange of 7 concentration starch solution

The recently published paper that approved the linearmodulus function can be expressed by [13 14]

119866 (119905) = 119886119905minus119899 (5)

Take the experiment data (Figure 2) to fit the function (5)withOrigin 80 and the fitted linearmodulus function can beexpressed by

119866 (119905) = 6469095119905minus019167 (6)

The linear modulus function119866(119905) characterizes the linearproperty of material during the small deformation Withcertain deformation the relationship of stress and strain islinear and the shear modulus119866(119905) is only dependent on time119905 With the strain increasing the relationship of stress andstrain is nonlinear and shear modulus 119866(119905 120574) is dependenton time and strain The shear modulus function 119866(119905 120574) canbe expressed by [15 16]

119866 (119905 120574) = 119866 (119905) ℎ (120574) (7)

where ℎ(120574) is a damping function and it is a function of strain120574The damping functionwas added into the shearmodulus tocharacterize the nonlinear property of material It describesthe relationship of the shear modulus and the strain

Mathematical Problems in Engineering 3

Table 1 The value of strain at t = 50 s in the different strainrelaxation test

Strain 03 1 4 20 100 300 600Strain 120574 3082 2418 1199 3088 05657 01914 0078

Table 2 The value of dumping function at different strain

Strain 0 0007 0037 0197 1 3 6ℎ(120574) 1 07845 0389 01 0018 0006 00025

Derived from (7) ℎ(120574) can be expressed by

ℎ (120574) =119866 (119905 120574)

119866 (119905) (8)

Many measurements of the relaxation modulus were per-formed in a nonlinear shear strain range of 120574 = 4 to10 (Figure 3) where the starch solution behaves stronglynonlinear

According to the published data of damping function[17 18] the following equation can be selected as the starchsolutionrsquos damping function

ℎ (120574) = 119890minus119899120574 (9)

Therefore the relaxation modulus can be expressed asfollows

119866 (119905 120574) = 119866 (119905) 119890minus1198991120574= 119886119905minus1198992 lowast 119890minus1198991120574 (10)

The measurements data was shown in Tables 1 and 2The dumping function can be fitted by the measurements

data The fitted result was shown as follow

ℎ (120574) = 119890minus2638120574 (11)

Therefore the shear modulus can be expressed as follow

119866 (119905 120574) = 6469095119905minus019167lowast 119890minus2638120574 (12)

4 Calculation of Nonlinear Material Functions

The material function of starch solution can be establishedbased on the Lodge model and the stress under smalldeformation can be expressed by

120590 (119905) = int

119905

minusinfin

119866(119905 minus 1199051015840 120576 (1199051015840)) lowastsdot

120576 (1199051015840) 1198891199051015840 (13)

Take (12) into (13) and the material function of starchsolution can be expressed by

120590 (119905) = int

119905

minusinfin

64690951199051015840minus019167

lowast 119890minus2638120574lowastsdot

120576 (1199051015840) 1198891199051015840 (14)

where 120574 is the current strain The shear history can bedescribed by the following

1205741199051199051015840 =

sdot

1205740(119905 minus 1199051015840) for 119905 minus 1199051015840 lt 119905

sdot

1205740119905 for 119905 minus 1199051015840 ge 119905

(15)

7 strarch solution

Strain 03 stress relaxation stepStrain 4 stress relaxation stepStrain 20 stress relaxation stepStrain 100 stress relaxation stepStrain 300 stress relaxation stepStrain 600 stress relaxation step

Time (s)

1E7

1E6

1E5

10000

1000

100

10

1

01

001

1Eminus3

Mod

ulus

G(t)

(Pa)

0 50 100 150 200 250 300

Figure 3 119866(119905 120574) curve during the stress relaxation test underdifferent strain for 03 4 20 100 300 600 respectively

7 starch solution

Shear rate sweep from 01 to 10 (flow step)Time (s)

Stra

in

Shea

r rat

e

Shea

r stre

ss (P

a)0 100 200 300 400 500 600 700 800 900 1000

0

25

5

75

10

125

15

175

20

0

25

5

75

10

125

15

175

20

0

2

4

6

8

12

10

450

400

350

300

250

200

150

100

50

0

225

Visc

osity

(Pamiddot

s)

Figure 4 Shear rate step flow test

The verified experiment was carried out and the resultwas shown in Figures 4 and 5

In the shear rate sweep test the time and shear rate areknown Therefore the strain can be calculated by shear rateand time The above parameters were taken into (14) and thepredict result was shown in Figure 5

Viscosity-shear rate curve of starch solution was shownin Figure 6

It indicates that the viscosity of starch solution willbecome thin with the shear rate increasing

The predicted results indicate that the material functionconstructed with memory function describes the flow behav-ior during the shear rate step test The shape of predicts

4 Mathematical Problems in Engineering

Calculated dataMeasurement data

Shea

r stre

ss (p

a)

Shear rate

25

20

15

10

5

00 1 2 3 4 5 6 7 8 9 10

Figure 5 Predicted result of shear stress during the shear rate sweeptest

Calculated dataMeasurement data

Shear rate

25

20

15

10

5

00 1 2 3 4 5 6 7 8 9 10

Visc

osity

(Pamiddot

s)

Figure 6 Viscosity-shear rate curve

line based on the material function was very similar to theshape of measured data lineWhen the shear rate increases toinfinite both the predicted data and test data are close to thesame value

5 Conclusion

The memory function of starch solution can be constructedby the shear relaxation test Based on the memory functionthe material function of starch solution was established topredict the shear stress and viscosity during the steady shearflow The predicted result shows that the material functioncan be used to describe the behavior of starch solution duringthe shear process

Acknowledgment

This work was supported by the Fundamental ResearchFunds for the Central Universities under Grant noJUSRP11203

References

[1] D Eidam W M Kulicke K Kuhn and R Stute ldquoFormationof maize starch gels selectively regulated by the addition ofhydrocolloidsrdquo Starch vol 47 pp 378ndash384 1995

[2] L Quintieri A Monteverde and L Caputo ldquoChanges inprolamin and high resistant starch composition during the pro-duction process of Boza a traditional cereal-based beveragerdquoEuropean FoodResearch andTechnology vol 235 no 4 pp 699ndash709 2012

[3] L Duo and G Dan ldquoImplementing high weight measurementprecision in package machines by using 8031 single chip micro-computerrdquo Journal of Tianjin University of Commence vol 4 pp8ndash14 1994

[4] C Luo ldquoThe calculation of the solid conveying volumetric ratioflow rate of the food extruderrdquo Packaging and Food Machineryvol 26 no 2 pp 30ndash32 2008

[5] J F Steffe Rheological Methods in Food Process EngineeringFreeman Press East Lansing Mich USA 1996

[6] A S Lodge Elastic Liquids Academic Press London UK 1964[7] A S Lodge and J Meissner ldquoComparison of network theory

predictions with stresstime data in shear and elongation for alow-density polyethylene meltrdquo Rheologica Acta vol 12 no 1pp 41ndash47 1973

[8] M Sugimoto Y Masubuchi J Takimoto and K KoyamaldquoMelt rheology of polypropylene containing small amounts ofhigh molecular weight chain I Shear flowrdquo Journal of PolymerScience B vol 39 no 21 pp 2692ndash2704 2001

[9] M H Wagner ldquoAnalysis of time-dependent non-linear stress-growth data for shear and elongational flow of a low-densitybranched polyethylene meltrdquo Rheologica Acta vol 15 no 2 pp136ndash142 1976

[10] M H Wagner ldquoPrediction of primary normal stress differencefrom shear viscosity data using a single integral constitutiveequationrdquo Rheologica Acta vol 16 no 1 pp 43ndash50 1977

[11] J H Yu P H S Santos and O H Campanella ldquoA study tocharacterize the mechanical behavior of semi-solid viscoelasticsystems under compression chewing case study of agar gelrdquoJournal of Texture Studies vol 43 no 6 pp 459ndash467 2012

[12] J D Ferry Viscoelastic Properties of Polymers John Wiley ampSons New York NY USA 1980

[13] K Osaki ldquoOn the damping function of shear relaxation modu-lus for entangled polymersrdquo Rheologica Acta vol 32 no 5 pp429ndash437 1993

[14] Q Zheng W Wang Q Yu J Yu L He and H Tan ldquoNon-linear viscoelastic behavior of styrene-[ethylene-(ethylene-propylene)]- styrene block copolymerrdquo Journal of PolymerScience B vol 44 no 9 pp 1309ndash1319 2006

[15] F A Morrison Understanding Rheology Oxford universitypress New York NY USA 2001

[16] W Wang Z Lu Y Cao J Chen J Wang and Q ZhengldquoInvestigation and prediction on the nonlinear viscoelasticbehaviors of nylon1212 toughened with elastomerrdquo Journal ofApplied Polymer Science vol 123 no 3 pp 1283ndash1292 2012

Mathematical Problems in Engineering 5

[17] H Watanabe T Sato K Osaki et al ldquoRheological images ofpoly(vinyl chloride) gels 4 Nonlinear behavior in a critical gelstaterdquoMacromolecules vol 31 no 13 pp 4198ndash4204 1998

[18] VH Rolon-Garrido andMHWagner ldquoThedamping functionin rheologyrdquo Rheologica Acta vol 48 no 3 pp 245ndash284 2009

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Page 2: Research Article Analysis on Nonlinear Stress-Growth Data ...

2 Mathematical Problems in Engineering

7 starch solution

Strain sweep from 00001 to 10 strain sweep step

Strain ()

0101001

1

11

10

10

10

100

01

1

10

100

100 1000 10000

100

G998400

(Pa)

G998400998400

(Pa)

120575(d

egre

es)

Figure 1 Strain sweep test from 00001 to 10 at the frequency 1

7 starch solution

Strain is 03 stress relaxation test

Time (s)

1

10

100

1000

10000

1E5

Mod

ulus

G(t)

(Pa)

0 50 100 150 200 250 300

Figure 2 Relaxation test within linear range of strain

and distilled water were used tomake different concentrationstarch solution The whole experiment was performed onthe Rheometer AR-2000 from TA instruments Ltd The conehead was installed and its angle is 28 degree The constanttest temperature is 25∘C

High shear rate and long time shear test were performedto find if the shear process affects the strain relaxation testShear rate influence on the strain can be found Thereforethememory function can be established by themany differentstrain relaxation tests

3 Memory Function for the NonlinearViscoelastic Behavior

Thememory function can characterize the mechanical prop-erty of the specific material [12] According toWagner [9 10]

for simple shear flow the generalized memory function isexpressed by

119872(119905 minus 1199051015840 1205741199051199051015840) =sdot

119872 (119905 minus 1199051015840) ℎ (1205741199051199051015840) (2)

wheresdot

119872 (119905minus1199051015840) is the linearmodulus ofmaterial under small

deformation It describes the linear relationship betweenthe strain and stress of material The nonlinearity of therheological behavior is only characterized by the dumpingfunction ℎ(120574

1199051199051015840)

For simple shear flow the well known relations for theshear stress 120590(119905) can be expressed by

120590 (119905) = int

infin

0

119872(119905 minus 1199051015840) 12057411990511990510158401198891199051015840 (3)

In order to establish the shear modulus function and thedamping function the linear range of the relationship of thestress and strainmust be foundwith strain sweep test Figure 1shows that the storage modulus1198661015840 the lost modulus 11986610158401015840 anddifferent degree delta are almost constant when the strain isless than 001 It indicates that the relationship of stress andstrain of starch solution is linear during the step in shearstrain from0 to 001Therefore in the linear viscoelastic rangethe shear relaxation modulus 119866(119905) can be given by

119866 (119905) asymp 119866 (119905 120574) =120590 (119905)

120574 (4)

According to the strain sweep test result the suitablestrain relaxation test was carried out The measurement dataof relaxation test was shown in Figure 2 The strain value ofrelaxation test is 03 and it belongs to the linear viscoelasticrange of 7 concentration starch solution

The recently published paper that approved the linearmodulus function can be expressed by [13 14]

119866 (119905) = 119886119905minus119899 (5)

Take the experiment data (Figure 2) to fit the function (5)withOrigin 80 and the fitted linearmodulus function can beexpressed by

119866 (119905) = 6469095119905minus019167 (6)

The linear modulus function119866(119905) characterizes the linearproperty of material during the small deformation Withcertain deformation the relationship of stress and strain islinear and the shear modulus119866(119905) is only dependent on time119905 With the strain increasing the relationship of stress andstrain is nonlinear and shear modulus 119866(119905 120574) is dependenton time and strain The shear modulus function 119866(119905 120574) canbe expressed by [15 16]

119866 (119905 120574) = 119866 (119905) ℎ (120574) (7)

where ℎ(120574) is a damping function and it is a function of strain120574The damping functionwas added into the shearmodulus tocharacterize the nonlinear property of material It describesthe relationship of the shear modulus and the strain

Mathematical Problems in Engineering 3

Table 1 The value of strain at t = 50 s in the different strainrelaxation test

Strain 03 1 4 20 100 300 600Strain 120574 3082 2418 1199 3088 05657 01914 0078

Table 2 The value of dumping function at different strain

Strain 0 0007 0037 0197 1 3 6ℎ(120574) 1 07845 0389 01 0018 0006 00025

Derived from (7) ℎ(120574) can be expressed by

ℎ (120574) =119866 (119905 120574)

119866 (119905) (8)

Many measurements of the relaxation modulus were per-formed in a nonlinear shear strain range of 120574 = 4 to10 (Figure 3) where the starch solution behaves stronglynonlinear

According to the published data of damping function[17 18] the following equation can be selected as the starchsolutionrsquos damping function

ℎ (120574) = 119890minus119899120574 (9)

Therefore the relaxation modulus can be expressed asfollows

119866 (119905 120574) = 119866 (119905) 119890minus1198991120574= 119886119905minus1198992 lowast 119890minus1198991120574 (10)

The measurements data was shown in Tables 1 and 2The dumping function can be fitted by the measurements

data The fitted result was shown as follow

ℎ (120574) = 119890minus2638120574 (11)

Therefore the shear modulus can be expressed as follow

119866 (119905 120574) = 6469095119905minus019167lowast 119890minus2638120574 (12)

4 Calculation of Nonlinear Material Functions

The material function of starch solution can be establishedbased on the Lodge model and the stress under smalldeformation can be expressed by

120590 (119905) = int

119905

minusinfin

119866(119905 minus 1199051015840 120576 (1199051015840)) lowastsdot

120576 (1199051015840) 1198891199051015840 (13)

Take (12) into (13) and the material function of starchsolution can be expressed by

120590 (119905) = int

119905

minusinfin

64690951199051015840minus019167

lowast 119890minus2638120574lowastsdot

120576 (1199051015840) 1198891199051015840 (14)

where 120574 is the current strain The shear history can bedescribed by the following

1205741199051199051015840 =

sdot

1205740(119905 minus 1199051015840) for 119905 minus 1199051015840 lt 119905

sdot

1205740119905 for 119905 minus 1199051015840 ge 119905

(15)

7 strarch solution

Strain 03 stress relaxation stepStrain 4 stress relaxation stepStrain 20 stress relaxation stepStrain 100 stress relaxation stepStrain 300 stress relaxation stepStrain 600 stress relaxation step

Time (s)

1E7

1E6

1E5

10000

1000

100

10

1

01

001

1Eminus3

Mod

ulus

G(t)

(Pa)

0 50 100 150 200 250 300

Figure 3 119866(119905 120574) curve during the stress relaxation test underdifferent strain for 03 4 20 100 300 600 respectively

7 starch solution

Shear rate sweep from 01 to 10 (flow step)Time (s)

Stra

in

Shea

r rat

e

Shea

r stre

ss (P

a)0 100 200 300 400 500 600 700 800 900 1000

0

25

5

75

10

125

15

175

20

0

25

5

75

10

125

15

175

20

0

2

4

6

8

12

10

450

400

350

300

250

200

150

100

50

0

225

Visc

osity

(Pamiddot

s)

Figure 4 Shear rate step flow test

The verified experiment was carried out and the resultwas shown in Figures 4 and 5

In the shear rate sweep test the time and shear rate areknown Therefore the strain can be calculated by shear rateand time The above parameters were taken into (14) and thepredict result was shown in Figure 5

Viscosity-shear rate curve of starch solution was shownin Figure 6

It indicates that the viscosity of starch solution willbecome thin with the shear rate increasing

The predicted results indicate that the material functionconstructed with memory function describes the flow behav-ior during the shear rate step test The shape of predicts

4 Mathematical Problems in Engineering

Calculated dataMeasurement data

Shea

r stre

ss (p

a)

Shear rate

25

20

15

10

5

00 1 2 3 4 5 6 7 8 9 10

Figure 5 Predicted result of shear stress during the shear rate sweeptest

Calculated dataMeasurement data

Shear rate

25

20

15

10

5

00 1 2 3 4 5 6 7 8 9 10

Visc

osity

(Pamiddot

s)

Figure 6 Viscosity-shear rate curve

line based on the material function was very similar to theshape of measured data lineWhen the shear rate increases toinfinite both the predicted data and test data are close to thesame value

5 Conclusion

The memory function of starch solution can be constructedby the shear relaxation test Based on the memory functionthe material function of starch solution was established topredict the shear stress and viscosity during the steady shearflow The predicted result shows that the material functioncan be used to describe the behavior of starch solution duringthe shear process

Acknowledgment

This work was supported by the Fundamental ResearchFunds for the Central Universities under Grant noJUSRP11203

References

[1] D Eidam W M Kulicke K Kuhn and R Stute ldquoFormationof maize starch gels selectively regulated by the addition ofhydrocolloidsrdquo Starch vol 47 pp 378ndash384 1995

[2] L Quintieri A Monteverde and L Caputo ldquoChanges inprolamin and high resistant starch composition during the pro-duction process of Boza a traditional cereal-based beveragerdquoEuropean FoodResearch andTechnology vol 235 no 4 pp 699ndash709 2012

[3] L Duo and G Dan ldquoImplementing high weight measurementprecision in package machines by using 8031 single chip micro-computerrdquo Journal of Tianjin University of Commence vol 4 pp8ndash14 1994

[4] C Luo ldquoThe calculation of the solid conveying volumetric ratioflow rate of the food extruderrdquo Packaging and Food Machineryvol 26 no 2 pp 30ndash32 2008

[5] J F Steffe Rheological Methods in Food Process EngineeringFreeman Press East Lansing Mich USA 1996

[6] A S Lodge Elastic Liquids Academic Press London UK 1964[7] A S Lodge and J Meissner ldquoComparison of network theory

predictions with stresstime data in shear and elongation for alow-density polyethylene meltrdquo Rheologica Acta vol 12 no 1pp 41ndash47 1973

[8] M Sugimoto Y Masubuchi J Takimoto and K KoyamaldquoMelt rheology of polypropylene containing small amounts ofhigh molecular weight chain I Shear flowrdquo Journal of PolymerScience B vol 39 no 21 pp 2692ndash2704 2001

[9] M H Wagner ldquoAnalysis of time-dependent non-linear stress-growth data for shear and elongational flow of a low-densitybranched polyethylene meltrdquo Rheologica Acta vol 15 no 2 pp136ndash142 1976

[10] M H Wagner ldquoPrediction of primary normal stress differencefrom shear viscosity data using a single integral constitutiveequationrdquo Rheologica Acta vol 16 no 1 pp 43ndash50 1977

[11] J H Yu P H S Santos and O H Campanella ldquoA study tocharacterize the mechanical behavior of semi-solid viscoelasticsystems under compression chewing case study of agar gelrdquoJournal of Texture Studies vol 43 no 6 pp 459ndash467 2012

[12] J D Ferry Viscoelastic Properties of Polymers John Wiley ampSons New York NY USA 1980

[13] K Osaki ldquoOn the damping function of shear relaxation modu-lus for entangled polymersrdquo Rheologica Acta vol 32 no 5 pp429ndash437 1993

[14] Q Zheng W Wang Q Yu J Yu L He and H Tan ldquoNon-linear viscoelastic behavior of styrene-[ethylene-(ethylene-propylene)]- styrene block copolymerrdquo Journal of PolymerScience B vol 44 no 9 pp 1309ndash1319 2006

[15] F A Morrison Understanding Rheology Oxford universitypress New York NY USA 2001

[16] W Wang Z Lu Y Cao J Chen J Wang and Q ZhengldquoInvestigation and prediction on the nonlinear viscoelasticbehaviors of nylon1212 toughened with elastomerrdquo Journal ofApplied Polymer Science vol 123 no 3 pp 1283ndash1292 2012

Mathematical Problems in Engineering 5

[17] H Watanabe T Sato K Osaki et al ldquoRheological images ofpoly(vinyl chloride) gels 4 Nonlinear behavior in a critical gelstaterdquoMacromolecules vol 31 no 13 pp 4198ndash4204 1998

[18] VH Rolon-Garrido andMHWagner ldquoThedamping functionin rheologyrdquo Rheologica Acta vol 48 no 3 pp 245ndash284 2009

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MathematicsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Mathematical Problems in Engineering

Hindawi Publishing Corporationhttpwwwhindawicom

Differential EquationsInternational Journal of

Volume 2014

Applied MathematicsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Probability and StatisticsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Mathematical PhysicsAdvances in

Complex AnalysisJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

OptimizationJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CombinatoricsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Operations ResearchAdvances in

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Function Spaces

Abstract and Applied AnalysisHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of Mathematics and Mathematical Sciences

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Algebra

Discrete Dynamics in Nature and Society

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Decision SciencesAdvances in

Discrete MathematicsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom

Volume 2014 Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Stochastic AnalysisInternational Journal of

Page 3: Research Article Analysis on Nonlinear Stress-Growth Data ...

Mathematical Problems in Engineering 3

Table 1 The value of strain at t = 50 s in the different strainrelaxation test

Strain 03 1 4 20 100 300 600Strain 120574 3082 2418 1199 3088 05657 01914 0078

Table 2 The value of dumping function at different strain

Strain 0 0007 0037 0197 1 3 6ℎ(120574) 1 07845 0389 01 0018 0006 00025

Derived from (7) ℎ(120574) can be expressed by

ℎ (120574) =119866 (119905 120574)

119866 (119905) (8)

Many measurements of the relaxation modulus were per-formed in a nonlinear shear strain range of 120574 = 4 to10 (Figure 3) where the starch solution behaves stronglynonlinear

According to the published data of damping function[17 18] the following equation can be selected as the starchsolutionrsquos damping function

ℎ (120574) = 119890minus119899120574 (9)

Therefore the relaxation modulus can be expressed asfollows

119866 (119905 120574) = 119866 (119905) 119890minus1198991120574= 119886119905minus1198992 lowast 119890minus1198991120574 (10)

The measurements data was shown in Tables 1 and 2The dumping function can be fitted by the measurements

data The fitted result was shown as follow

ℎ (120574) = 119890minus2638120574 (11)

Therefore the shear modulus can be expressed as follow

119866 (119905 120574) = 6469095119905minus019167lowast 119890minus2638120574 (12)

4 Calculation of Nonlinear Material Functions

The material function of starch solution can be establishedbased on the Lodge model and the stress under smalldeformation can be expressed by

120590 (119905) = int

119905

minusinfin

119866(119905 minus 1199051015840 120576 (1199051015840)) lowastsdot

120576 (1199051015840) 1198891199051015840 (13)

Take (12) into (13) and the material function of starchsolution can be expressed by

120590 (119905) = int

119905

minusinfin

64690951199051015840minus019167

lowast 119890minus2638120574lowastsdot

120576 (1199051015840) 1198891199051015840 (14)

where 120574 is the current strain The shear history can bedescribed by the following

1205741199051199051015840 =

sdot

1205740(119905 minus 1199051015840) for 119905 minus 1199051015840 lt 119905

sdot

1205740119905 for 119905 minus 1199051015840 ge 119905

(15)

7 strarch solution

Strain 03 stress relaxation stepStrain 4 stress relaxation stepStrain 20 stress relaxation stepStrain 100 stress relaxation stepStrain 300 stress relaxation stepStrain 600 stress relaxation step

Time (s)

1E7

1E6

1E5

10000

1000

100

10

1

01

001

1Eminus3

Mod

ulus

G(t)

(Pa)

0 50 100 150 200 250 300

Figure 3 119866(119905 120574) curve during the stress relaxation test underdifferent strain for 03 4 20 100 300 600 respectively

7 starch solution

Shear rate sweep from 01 to 10 (flow step)Time (s)

Stra

in

Shea

r rat

e

Shea

r stre

ss (P

a)0 100 200 300 400 500 600 700 800 900 1000

0

25

5

75

10

125

15

175

20

0

25

5

75

10

125

15

175

20

0

2

4

6

8

12

10

450

400

350

300

250

200

150

100

50

0

225

Visc

osity

(Pamiddot

s)

Figure 4 Shear rate step flow test

The verified experiment was carried out and the resultwas shown in Figures 4 and 5

In the shear rate sweep test the time and shear rate areknown Therefore the strain can be calculated by shear rateand time The above parameters were taken into (14) and thepredict result was shown in Figure 5

Viscosity-shear rate curve of starch solution was shownin Figure 6

It indicates that the viscosity of starch solution willbecome thin with the shear rate increasing

The predicted results indicate that the material functionconstructed with memory function describes the flow behav-ior during the shear rate step test The shape of predicts

4 Mathematical Problems in Engineering

Calculated dataMeasurement data

Shea

r stre

ss (p

a)

Shear rate

25

20

15

10

5

00 1 2 3 4 5 6 7 8 9 10

Figure 5 Predicted result of shear stress during the shear rate sweeptest

Calculated dataMeasurement data

Shear rate

25

20

15

10

5

00 1 2 3 4 5 6 7 8 9 10

Visc

osity

(Pamiddot

s)

Figure 6 Viscosity-shear rate curve

line based on the material function was very similar to theshape of measured data lineWhen the shear rate increases toinfinite both the predicted data and test data are close to thesame value

5 Conclusion

The memory function of starch solution can be constructedby the shear relaxation test Based on the memory functionthe material function of starch solution was established topredict the shear stress and viscosity during the steady shearflow The predicted result shows that the material functioncan be used to describe the behavior of starch solution duringthe shear process

Acknowledgment

This work was supported by the Fundamental ResearchFunds for the Central Universities under Grant noJUSRP11203

References

[1] D Eidam W M Kulicke K Kuhn and R Stute ldquoFormationof maize starch gels selectively regulated by the addition ofhydrocolloidsrdquo Starch vol 47 pp 378ndash384 1995

[2] L Quintieri A Monteverde and L Caputo ldquoChanges inprolamin and high resistant starch composition during the pro-duction process of Boza a traditional cereal-based beveragerdquoEuropean FoodResearch andTechnology vol 235 no 4 pp 699ndash709 2012

[3] L Duo and G Dan ldquoImplementing high weight measurementprecision in package machines by using 8031 single chip micro-computerrdquo Journal of Tianjin University of Commence vol 4 pp8ndash14 1994

[4] C Luo ldquoThe calculation of the solid conveying volumetric ratioflow rate of the food extruderrdquo Packaging and Food Machineryvol 26 no 2 pp 30ndash32 2008

[5] J F Steffe Rheological Methods in Food Process EngineeringFreeman Press East Lansing Mich USA 1996

[6] A S Lodge Elastic Liquids Academic Press London UK 1964[7] A S Lodge and J Meissner ldquoComparison of network theory

predictions with stresstime data in shear and elongation for alow-density polyethylene meltrdquo Rheologica Acta vol 12 no 1pp 41ndash47 1973

[8] M Sugimoto Y Masubuchi J Takimoto and K KoyamaldquoMelt rheology of polypropylene containing small amounts ofhigh molecular weight chain I Shear flowrdquo Journal of PolymerScience B vol 39 no 21 pp 2692ndash2704 2001

[9] M H Wagner ldquoAnalysis of time-dependent non-linear stress-growth data for shear and elongational flow of a low-densitybranched polyethylene meltrdquo Rheologica Acta vol 15 no 2 pp136ndash142 1976

[10] M H Wagner ldquoPrediction of primary normal stress differencefrom shear viscosity data using a single integral constitutiveequationrdquo Rheologica Acta vol 16 no 1 pp 43ndash50 1977

[11] J H Yu P H S Santos and O H Campanella ldquoA study tocharacterize the mechanical behavior of semi-solid viscoelasticsystems under compression chewing case study of agar gelrdquoJournal of Texture Studies vol 43 no 6 pp 459ndash467 2012

[12] J D Ferry Viscoelastic Properties of Polymers John Wiley ampSons New York NY USA 1980

[13] K Osaki ldquoOn the damping function of shear relaxation modu-lus for entangled polymersrdquo Rheologica Acta vol 32 no 5 pp429ndash437 1993

[14] Q Zheng W Wang Q Yu J Yu L He and H Tan ldquoNon-linear viscoelastic behavior of styrene-[ethylene-(ethylene-propylene)]- styrene block copolymerrdquo Journal of PolymerScience B vol 44 no 9 pp 1309ndash1319 2006

[15] F A Morrison Understanding Rheology Oxford universitypress New York NY USA 2001

[16] W Wang Z Lu Y Cao J Chen J Wang and Q ZhengldquoInvestigation and prediction on the nonlinear viscoelasticbehaviors of nylon1212 toughened with elastomerrdquo Journal ofApplied Polymer Science vol 123 no 3 pp 1283ndash1292 2012

Mathematical Problems in Engineering 5

[17] H Watanabe T Sato K Osaki et al ldquoRheological images ofpoly(vinyl chloride) gels 4 Nonlinear behavior in a critical gelstaterdquoMacromolecules vol 31 no 13 pp 4198ndash4204 1998

[18] VH Rolon-Garrido andMHWagner ldquoThedamping functionin rheologyrdquo Rheologica Acta vol 48 no 3 pp 245ndash284 2009

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MathematicsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Mathematical Problems in Engineering

Hindawi Publishing Corporationhttpwwwhindawicom

Differential EquationsInternational Journal of

Volume 2014

Applied MathematicsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Probability and StatisticsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Mathematical PhysicsAdvances in

Complex AnalysisJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

OptimizationJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CombinatoricsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Operations ResearchAdvances in

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Function Spaces

Abstract and Applied AnalysisHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of Mathematics and Mathematical Sciences

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Algebra

Discrete Dynamics in Nature and Society

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Decision SciencesAdvances in

Discrete MathematicsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom

Volume 2014 Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Stochastic AnalysisInternational Journal of

Page 4: Research Article Analysis on Nonlinear Stress-Growth Data ...

4 Mathematical Problems in Engineering

Calculated dataMeasurement data

Shea

r stre

ss (p

a)

Shear rate

25

20

15

10

5

00 1 2 3 4 5 6 7 8 9 10

Figure 5 Predicted result of shear stress during the shear rate sweeptest

Calculated dataMeasurement data

Shear rate

25

20

15

10

5

00 1 2 3 4 5 6 7 8 9 10

Visc

osity

(Pamiddot

s)

Figure 6 Viscosity-shear rate curve

line based on the material function was very similar to theshape of measured data lineWhen the shear rate increases toinfinite both the predicted data and test data are close to thesame value

5 Conclusion

The memory function of starch solution can be constructedby the shear relaxation test Based on the memory functionthe material function of starch solution was established topredict the shear stress and viscosity during the steady shearflow The predicted result shows that the material functioncan be used to describe the behavior of starch solution duringthe shear process

Acknowledgment

This work was supported by the Fundamental ResearchFunds for the Central Universities under Grant noJUSRP11203

References

[1] D Eidam W M Kulicke K Kuhn and R Stute ldquoFormationof maize starch gels selectively regulated by the addition ofhydrocolloidsrdquo Starch vol 47 pp 378ndash384 1995

[2] L Quintieri A Monteverde and L Caputo ldquoChanges inprolamin and high resistant starch composition during the pro-duction process of Boza a traditional cereal-based beveragerdquoEuropean FoodResearch andTechnology vol 235 no 4 pp 699ndash709 2012

[3] L Duo and G Dan ldquoImplementing high weight measurementprecision in package machines by using 8031 single chip micro-computerrdquo Journal of Tianjin University of Commence vol 4 pp8ndash14 1994

[4] C Luo ldquoThe calculation of the solid conveying volumetric ratioflow rate of the food extruderrdquo Packaging and Food Machineryvol 26 no 2 pp 30ndash32 2008

[5] J F Steffe Rheological Methods in Food Process EngineeringFreeman Press East Lansing Mich USA 1996

[6] A S Lodge Elastic Liquids Academic Press London UK 1964[7] A S Lodge and J Meissner ldquoComparison of network theory

predictions with stresstime data in shear and elongation for alow-density polyethylene meltrdquo Rheologica Acta vol 12 no 1pp 41ndash47 1973

[8] M Sugimoto Y Masubuchi J Takimoto and K KoyamaldquoMelt rheology of polypropylene containing small amounts ofhigh molecular weight chain I Shear flowrdquo Journal of PolymerScience B vol 39 no 21 pp 2692ndash2704 2001

[9] M H Wagner ldquoAnalysis of time-dependent non-linear stress-growth data for shear and elongational flow of a low-densitybranched polyethylene meltrdquo Rheologica Acta vol 15 no 2 pp136ndash142 1976

[10] M H Wagner ldquoPrediction of primary normal stress differencefrom shear viscosity data using a single integral constitutiveequationrdquo Rheologica Acta vol 16 no 1 pp 43ndash50 1977

[11] J H Yu P H S Santos and O H Campanella ldquoA study tocharacterize the mechanical behavior of semi-solid viscoelasticsystems under compression chewing case study of agar gelrdquoJournal of Texture Studies vol 43 no 6 pp 459ndash467 2012

[12] J D Ferry Viscoelastic Properties of Polymers John Wiley ampSons New York NY USA 1980

[13] K Osaki ldquoOn the damping function of shear relaxation modu-lus for entangled polymersrdquo Rheologica Acta vol 32 no 5 pp429ndash437 1993

[14] Q Zheng W Wang Q Yu J Yu L He and H Tan ldquoNon-linear viscoelastic behavior of styrene-[ethylene-(ethylene-propylene)]- styrene block copolymerrdquo Journal of PolymerScience B vol 44 no 9 pp 1309ndash1319 2006

[15] F A Morrison Understanding Rheology Oxford universitypress New York NY USA 2001

[16] W Wang Z Lu Y Cao J Chen J Wang and Q ZhengldquoInvestigation and prediction on the nonlinear viscoelasticbehaviors of nylon1212 toughened with elastomerrdquo Journal ofApplied Polymer Science vol 123 no 3 pp 1283ndash1292 2012

Mathematical Problems in Engineering 5

[17] H Watanabe T Sato K Osaki et al ldquoRheological images ofpoly(vinyl chloride) gels 4 Nonlinear behavior in a critical gelstaterdquoMacromolecules vol 31 no 13 pp 4198ndash4204 1998

[18] VH Rolon-Garrido andMHWagner ldquoThedamping functionin rheologyrdquo Rheologica Acta vol 48 no 3 pp 245ndash284 2009

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MathematicsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Mathematical Problems in Engineering

Hindawi Publishing Corporationhttpwwwhindawicom

Differential EquationsInternational Journal of

Volume 2014

Applied MathematicsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Probability and StatisticsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Mathematical PhysicsAdvances in

Complex AnalysisJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

OptimizationJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CombinatoricsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Operations ResearchAdvances in

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Function Spaces

Abstract and Applied AnalysisHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of Mathematics and Mathematical Sciences

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Algebra

Discrete Dynamics in Nature and Society

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Decision SciencesAdvances in

Discrete MathematicsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom

Volume 2014 Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Stochastic AnalysisInternational Journal of

Page 5: Research Article Analysis on Nonlinear Stress-Growth Data ...

Mathematical Problems in Engineering 5

[17] H Watanabe T Sato K Osaki et al ldquoRheological images ofpoly(vinyl chloride) gels 4 Nonlinear behavior in a critical gelstaterdquoMacromolecules vol 31 no 13 pp 4198ndash4204 1998

[18] VH Rolon-Garrido andMHWagner ldquoThedamping functionin rheologyrdquo Rheologica Acta vol 48 no 3 pp 245ndash284 2009

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MathematicsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Mathematical Problems in Engineering

Hindawi Publishing Corporationhttpwwwhindawicom

Differential EquationsInternational Journal of

Volume 2014

Applied MathematicsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Probability and StatisticsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Mathematical PhysicsAdvances in

Complex AnalysisJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

OptimizationJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CombinatoricsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Operations ResearchAdvances in

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Function Spaces

Abstract and Applied AnalysisHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of Mathematics and Mathematical Sciences

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Algebra

Discrete Dynamics in Nature and Society

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Decision SciencesAdvances in

Discrete MathematicsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom

Volume 2014 Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Stochastic AnalysisInternational Journal of

Page 6: Research Article Analysis on Nonlinear Stress-Growth Data ...

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MathematicsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Mathematical Problems in Engineering

Hindawi Publishing Corporationhttpwwwhindawicom

Differential EquationsInternational Journal of

Volume 2014

Applied MathematicsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Probability and StatisticsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Mathematical PhysicsAdvances in

Complex AnalysisJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

OptimizationJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CombinatoricsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Operations ResearchAdvances in

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Function Spaces

Abstract and Applied AnalysisHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of Mathematics and Mathematical Sciences

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Algebra

Discrete Dynamics in Nature and Society

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Decision SciencesAdvances in

Discrete MathematicsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom

Volume 2014 Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Stochastic AnalysisInternational Journal of


Recommended