A COMPARATIVE STUDY OF IMPACT ENERGY ABSORBING CAPACITY OF CIRCULAR TUBESOUR TEAM ANN PAVITHRA .J(1VI07ME007)CHETHAN .G (1VI07ME012) CHETHANA.K (1VI07ME014) SUNITHA .H.C (1VI07ME051)

8th semester, Department of Mechanical EngineeringVemana Institute of Technology, Bangalore

OUR GUIDEMr. B.G.VIJAYASIMHA REDDYAssistant Professor, HOD

CONTENTS Introduction Scope of the project Essentials of the project Experimental set-up Specimen specificationsExperimental procedure Equations used Photographic views Results & discussions Specific Energy absorption capacities Applications Future applications References

INTRODUCTIONThe project is about studying how a tubes behaves when it is acted upon by crushing/compressive loads & also to determine the energy absorption capacities of the tubes under study.

SCOPE OF THE PROJECT The crashworthiness of vehicles and the deformation of structures under dynamic loads has been an area of particularly active study in recent past. A number of energy-absorbing devices either embodied into vehicle structures or used as road side crash barriers are currently in use to mitigate the effects of impact. Metal tubes and tubular structures occupy an important place in the design of crashworthy systems as cost-competitive and performance effective energy- absorbing elements.

ESSENTIALS OF THE PROJECTTest specimens of different thickness material ( Aluminium) with specified dimensions. A universal testing machine (UTM) with necessary accessories.

A computer system with associated software, to observe analyze, & record the data.

A hardness testing machine to determine the hardness of the material.

EXPERIMENTAL SET-UPFig.1.0 Electronic Universal Testing machine (UTES-40)1. Loading Unit, 2. Servo Control Unit, 3. Computer Control

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SPECIMEN SPECIFICATIONSWe have confined our studies to Aluminium of different thickness in the form of hollow circular tubes with the following dimensions.

Diameter (d) : 50mm Length to diameter ratio (l/d): 3 Radius to thickness ratio (r/t): 10

Determination of material properties:Hardness test :

The Vickers hardness-testing machine was used to determine the hardness of the specimens. Hardness is defined as a measure of material resistance to localized plastic deformation .

Procedure :Selection of materials - We have selected Aluminium as material for conducting the test.Preparation of materials - The specimen was cut into desired dimension and surface finishing was done.The specimen was placed on the table and was focused on the Screen, then required load was applied.The indentation on the specimen was observed on the screen, and the readings were noted for calculating VHN.

EXPERIMENTAL PROCEDUREThe pipes were machined to the required specifications by subjecting them to secondary manufacturing processes (turning,boring,facing). The specimen was placed b/w jaws of the UTM and data (diameter, length, thickness, type of loading,material) were input to the computer which is associated with the UTM.

The compressive load is applied to the specimen under test and the result is obtained in the form of Load-Displacement curves.

The calculations of energy absorbed and specific energy absorption were carried out and compared with the theoretical values for each of the specimen under test.

Photographic viewsFig. 4.0 Axial-Compression of Aluminium Tube (Al-01)

Fig. 5.0 Axial-Compression of Aluminium Tube (Al-06)

RESULTS & DISCUSSIONS1234567812345678

Chart1

0.42

9.44

40.1

18.7

11.28

21.12

23.1

21

21.88

25.06

18.48

18.28

23.84

17.34

26.22

20.68

15.96

17.8

21.64

19.22

26.62

19.78

16

15.86

20.62

18.02

26.98

23.14

17.68

14.74

16.08

19.64

27.66

22.06

16.74

14.06

16.46

24.9

29.8

20.42

16.34

14.1

15.82

20.46

33.02

25.54

17.34

13.42

15.44

18.56

19.98

19.98

19.66

17.48

16.22

19

Dimensions (mm) L = 151.50, D = 50.50, t = 1.50

Displacement (mm)

Load (kN)

fig.(a) LOAD-DISPLACEMENT GRAPH OF AL6- AXIAL COMPRESSION TEST

Sheet1

00.42

29.44

440.1

6.0318.7

811.28

1021.12

1223.1

14.0121

1621.88

1825.06

2018.48

22.0118.28

24.0123.84

26.0117.34

28.0126.22

3220.68

32.0115.96

34.0117.8

36.0121.64

3819.22

40.0226.62

42.0119.78

4416

46.0115.86

4820.62

50.0218.02

52.0126.98

5423.14

56.0117.68

58.0114.74

60.0116.08

62.0119.64

6427.66

66.0122.06

68.0116.74

7014.06

7216.46

7424.9

7629.8

7820.42

80.0116.34

82.0114.1

8415.82

8620.46

88.0233.02

90.0125.54

9217.34

9413.42

9615.44

9818.56

100.0219.98

102.0119.98

10419.66

10617.48

10816.22

110.0119

Sheet2

Sheet3

Fig. 5.0 LOAD-DISPLACEMENT graph of AL-01 AXIAL COMPRESSION TESTDIMENSIONS (mm) L=150.0 D=50.0 t=2.50

EQUATIONS USEDSpecific Energy Absorption

Energy absorbedYield stress

Where VHN is the Vickers Hardness Number.

Axial Compression Tests results Table 2.0

MaterialSpecimen CodeDimensions mmMean loadKNEnergy absorbed KJDotL

Aluminum AL-01502.5015037.803.64AL-02502.5015037.514.70AL-03502.5015036.253.80AL-0450.51.50151.5018.502.03AL-0550.51.50151.5020.202.25AL-0650.51.50151.5021.002.31

Comparison of specific energy absorption Table 3.0

MaterialEmpty TubesTheoreticalexperimentalAL-0128.322.9AL-0228.229.6AL-0329.523.9AL-0413.712.7AL-0513.614.1AL-0613.512.4

SPECIFIC ENERGY ABSORPTION CAPACITIES 1.30 2.11 4.90 6.10

APPLICATIONSFig.6.0 shows a photograph of a car which collided head on with a truck

Fig.7.0 examples of collisions

Fig.8.0 Example of a roadside crash barrier

Fig.9.0 road-side crash barrier in use

AIRCRAFT LANDINGVideo 1.0 shows an emergency landing of an aircraft

Advanced technologyFig.10.0 sport biking (cylinders used as shock absorbers/fluid filled systems)

FUTURE APPLICATIONS Aerospace industries

Auto-mobiles * Bikes used for sport biking (as shock absorbers) * cars, trucks, buses, trains Nuclear power plants

Road-side crash barrier

Bottom of lift shafts to name a few.

ReferencesW. Abramowicz and N. Jones (1986), Dynamic progressive buckling of circular tubes, Intl. J. Impact Engg, 4, pp 243-270.

T. Wierzbicki and N. Jones (1983), Structural Crashworthiness, Chp-4, pp 96-114.

T. Y. Reddy (1978), Impact energy absorption using laterally compressed metal tubes, dissertation, University of Cambridge.

Roslan Ahmad (1990) Axial Compression of Thin Metal Tubes, dissertation, University of Manchester.

S. R. Reid, and T. Y. Reddy (1978), Effect of strain hardening on the lateral compression of tubes between rigid plates, Intl. J. Solid Structures, 14, pp 213-225.

N.Jones (1989), Structural Impact, University of Cambridge. Press, Cambridge.

P. D. Soden, W. Johnson, S. T. S. Al-Hassani (1977), Journal of strain analysis. Vol-12, pp 317-330.

T. Y. Reddy and S.R Reid (1979) , On obtaining material properties from ring compression test. Nucl. Engg Design 52, 257-263.

Google, pictures from Wikipedia.

****Table 2.0***Fig.7.0 shows a still of a car which collided head on with a truck*Fig.8.0 examples of collisions*APPLICATIONS**Fig.0.0 shows an emergency landing of an aircraft*