高载下不同试样尺度复合材料的动态黏弹性

 采用EPLEXOR500高载动态热机械分析仪(DMTA)在三点弯曲方式下考察了静态载荷和动态载荷对不同试样尺度T300/环氧648复合材料储能模量和损耗角正切的影响。结果表明，复合材料储能模量随动载增大而降低，随静载增大而升高，损耗角正切则随载荷增大而减小。减小试样跨距，增大厚度或宽度则会强化这一影响，尤其是对于储能模量。这一结果是由于试样内各种静态应力对其动态应变均存在“抑制作用”。这种作用再加上附加剪应变的影响导致试样尺寸对黏弹性影响规律存在一个过渡区，当静载/动载载荷比低于该过渡区时，储能模量随跨距的增大、厚度或宽度的减小而升高，高于此过渡区时储能模量变化规律完全相反。

Dynamic Viscoelasticity of Composites with Different Specimen Dimensions Under High Loads

The EPLEXOR 500 dynamic mechanic thermal analysis (DMTA) was used to investigate the effects of static and dynamic loads on storage modulus and loss tangent of T300/epoxy 648 in three-point bending. The results showed that the storage modulus decreases with increasing dynamic load and increases with increasing static load, and the loss tangent decreases with increase of any one of these two loads. These effects can be enhanced, especially for storage modulus, with decreasing the span or increasing the thickness or width of specimen. Such results are originated from the "suppression effects" of all the static stresses on dynamic strain. These suppression combined with the effect of additional shear stress leads to the fact that the storage modulus increases with the increase of span, decreases of thickness and width when the static-dynamic load ratio is below a certain transition zone, while the law will turn to the reverse when the ratio is above this zone.