| Popis: |
There is a relationship between the value of energy dissipation and characteristics of hysteresis loop during the first loading of cycles and mechanical features of composites. The ability to understand these relationship let us evaluate mechanical properties of composites during exploitation and can be helpful while searching for optimal parameters of processing. The investigation of basic mechanical properties of polyamide (PA) with 10, 20, 30, 40 and 50% glass fiber, polyacetal (POM) with 15, 25 and 35% glass fiber and 10, 15, 25% of mineral filler and polypropylen (PP) with the same contents of mineral filler was executed. The investigation during the first cycles of mechanical loading was made for three levels of load. Estimation of changes of dissipated energy and modulus of elasticity in function of number of cycles was done. Differences between the values of dissipated energy in the first following mechanical cycles inform us about the type of adhesion between the fillers and the polymer and about the change in the internal stresses in composites. The first loading cycles eliminate the extremely stressed areas in the volume of the material mainly through craking of adhesion connections between the reinforcement and the matrix. The value of dissipation energy in the first loading cycles can show the level of processing excellence and quality of the composite. |
