ANALYSES OF THERMAL AND RESIDUAL MICROSTRESSES IN PARTICLE AND MATRIX OF COMPOSITES

Elastic/plastic analyses are conducted on thermal and residual microstresses in particulate reinforced composites,according to a spherical symmetric model.It is shown that the thermal or residual stresses have a characteristic of short-range distribution;in a particle there is a constant hydrostatic pressure as the temperature drops,and there is a tension as the temperature rises.The radial stresses at the interface and in the matrix have the same sign as that in the particle,though the tangential and circumferential stresses' sign is opposite to that in the particle.There exists a critical temperature difference t_P over which the matrix near the particle starts to yield,and the yielded scale will expand as the temperature difference increases.The residual stress field is the same as the thermal one as the temperature changes.After a thermal cycle the residual stress field is zero when |t|p/sub>;else the residual stresses are induced in both the particle and matrix.The effects of the particle size and shape on the stress field are discussed.