Copyright© Abaris Training 2012

Abaris Training Resources, Inc.

With composite components you are generally looking for four types of flaws:

◦ Disbonds

◦ Delamination ◦ Porosity

◦ Inclusions

DISBOND

DELAMINATION

LAMINATED STRUCTURE

SUBSURFACE POROSITY

LAMINATED STRUCTURE

Visual Tap Testing Ultrasonic X-Ray Thermography Laser Shearography Holographic Laser Interferometry FTIR Spectrometry Acoustic Emission

Most Everyone Has Basic Equipment

Visually Detect (to some extent): ◦ Burns ◦ Disbonds ◦ Delamination ◦ Contamination ◦ Over-Stressed or

Fractured Areas

Delamination

Eye level abovereflected light.

Flashlight

Shadow

Effective Cheap, 25¢ & Up

Less Effective On Thick Laminates

Won’t Read Through Core Materials

Possible False Readings Must Be Able To Hear

Tapping Above Background Noise

Note the use of the forefinger on the spring-steel rod that allows the operator to detect subtle changes in response.

The Boeing/Wichitech digital tap hammer records response time in milliseconds. The shorter the response time, the less the structure absorbs the impact, thus detecting solid structure.

When a defect is found, the response time is longer, resulting a higher number.

This equipment is useful in quantifying damage in a thin-wall composite structure.

BondaScope 3100 Mechanical Impedance

Analysis (MIA) Mode

Pitch-catch mode

Courtesy of Inspection Technologies/NDT Systems

“A-Scan”

“C-Scan” Pulse – Echo

Transmit - Receive Transmit

Receive Through Transmission

Note the screen shows the initial “bang” and the

“back-wall” signal with some “grass” in between due to sound attenuation

Courtesy of Inspection Technologies

Courtesy of Inspection Technologies

Water-coupled C-scan inspection of CFRP Panel

Photo courtesy of RCBI WV Image courtesy of USN –No. Island

A Scan Technology ◦ Similar to C Scan Images

Uses “Arm” To Generate X,Y, and Z Coordinates

Computer Uses Information From Transducer To “Paint” A Picture

Courtesy of QinetiQ/NDTS

Sees changes in density

May See delaminations if viewed edgewise (CT scan)

Shows various Inclusions

Can show standing water*

Courtesy of Thermal Wave Imaging, Inc. 16

Light pulse excitation Heat conduction in sample IR detection of surface

temperature

Flashlamps IR camera

defect

PC

IR Image

Courtesy of Thermal Wave Imaging, Inc. 17

• Fast / real time inspection • Lightweight • Single operator / easy to use • Wide area • Non-contact • Reliable and repeatable • Low cost • Patented TSR processing • Environmentally friendly • Safe • Single side access • Complete NDT solution

747 Flap Track Fairing

Uses I.R. camera with Xenon lamps and a software package to coordinate heat input and mapping of heat transfer into structure

Photo courtesy of Alaska Airlines

An ‘active’ NDT technique using a Laser Interferometer to image surface strains associated with subsurface defects, anomalies, and internal structure.

Laser Imaging System

Interference Pattern Varies With Damage And Load

May Be Possible To Predict Bond Longevity In The Future

Wrapped Phase Map

Unwrapped Phase Map

Laser Shearography NDI of Composite Repairs

Disbond around repair

Porosity

Laser

Optics and Filter

Holographic Plate

Object Pre-load

Object Loaded

Uses a holographic plate to view/film structure

The technology has the potential to identify weak bonds

Acoustic Emission (AE) refers to the generation of transient elastic waves produced by a sudden redistribution of stress in a material. When a structure is subjected to an external stimulus (change in pressure, load, or temperature), localized sources trigger the release of energy, in the form of stress waves, which propagate to the

surface and are recorded by sensors. In composites, matrix cracking and fiber breakage and de-bonding contribute to acoustic emissions. The inherent problem is that a baseline from a composite structure “evolves” over time and therefore make

AE data difficult to interpret as part of the normal evolution or due to damage.

Courtesy of NDT Resource Center

Fourier transform infrared inspection of composites-Good for detection of heat damage and material quality inspection

Courtesy of Agilent Technologies

Eddy Current ◦ Composites are basically non-conductive

Dye Penetrant ◦ Ingress of dye into the structure it becomes an

irremovable contaminate.

No one method alone can find all types of defects in composite structures ◦ Multiple techniques are be necessary to fully

inspect most structures

Ultrasonic C-scan technology currently is the primary inspection technique used in manufacturing

Laser shearography/interferometry shows potential for eventually detecting weak bonds