THE X-RAY MEASUREMENT OF AXIAL AND HOOP RESIDUAL STRESSES IN MICROCOMPOSITE SPECIMENS

Thermal residual stresses were measured in microcomposites (Le., the elementary cell of a composite) using the X-ray diffraction method In order to overcome the geometry problem caused by this type of specimen, three different theoretical methods were applied to analyze the X-ray results. The first method was used previously for larger microcomposites (φ = 140 μm) and cannot be applied successfully here due to the small size of our specimen (φ = 20 μm). The two other methods (three-dimensional methods) have been used successfully and lead to similar results. The effects of the interphase type and thickness were studied. However, the uncertainty on thermal residual stress values are still at about 20%.