✍ Scribed by Rui Miranda Guedes; José J.L. Morais; António Torres Marques; Albert H. Cardon
No coin nor oath required. For personal study only.
After a brief introduction, where the question of durability related to composite materials is raised concerning the type of applications and the constituents of the composite material, some considerations are given about the interaction between physical and chemical ageing and its eect on the long-term behaviour of those materials. A comparison of dierent methodologies to de®ne models for the constitutive laws of the material is made, together with a reference to methodologies used for real structures in order to predict long-term behaviour. An algorithm to predict long-term laminate properties of ®bre reinforced composites is presented. In the procedure, the classical laminate plate theory was extended to include time-related response of composite materials for membrane and bending load. An ecient semi-direct time integration scheme, providing a stable integration process, was derived to be included in the numerical procedure. The present formulation enables solving problems related with creep, stress relaxation and rate dependent stress±strain behaviour for in-plane and bending loads. The results concerning studies related to the in¯uence of water and temperature on the long-term behaviour of ®bre reinforced composite, hence on the constitutive models, are presented. The experimental results shows that a combined time±temperature± moisture superposition principle (TTMSP) is not valid. This principle simply states that the eects of temperature and moisture on the viscoelastic properties can be uncoupled.
📜 SIMILAR VOLUMES
## Synopsis The applicability of time-temperature superposition to tensile stress relaxation of ABS plastics has been verified a t strains from 0.5 to 5% for temperatures in the range of l&50°C. Master curves have been compiled to predict the long-term stress relaxation at 23°C. and a stress-strai