stress and residual stress are the main problems in the operating performance of materials. they are the principal causes of material failure and can affect life time of component. however measurement or predictions of them are typically difficult. two common non-destructive methods, x-ray diffraction and ultrasound are not reliable methods for subsurface residual stress measurements and destru...

in this paper a new method for nondestructive testing or nondestructive evaluation is proposed for glass-epoxy composite. for this purpose, impact-echo is used to evaluate the properties of composite materials, detecting internal defects and thickness measurement. in the impact-echo method a steel ball impacts on a composite plate and generates stress waves or p-waves which will be transferred ...

The problem of plastic anti-personal mine detection is well known. These devices are typically 75mm in diameter and between 25mm to 50mm in thickness. Some types contain no metal, but their explosive (RDX, TNT) can be considered as a dielectric material with a dielectric constant between 3.5 and 4.0. This electromagnetic property enables a radar to identify mines. It is true that the radars ope...