Experimental Investigation,numerical Simulation And Mechanism Exploration Of Material Dynamic Strength

Material strength is one of the important mechanical properties of material, it is important to material processing, structure designing, engineering constructing, management operating etc. To investigate strength of material is important for exploiting the usage of material, designing reasonable construction, promoting safety construction and optimum management.Generally, material strength we called refers to static mechanical characteristic of material. In the real world, material or structure not only undertakes quasi-static loads which altered slowly, but also bears dynamic loads which varied rapidly, such as earthquake load, impulsive load, and shaking load. The behaviors of material or structure under these loads call its dynamic properties, which include dynamic strength. Dynamic strength is one of the key points in material research, as well as a difficulty. Although there have been large numbers of research achievements of material dynamic strength, no common agreement has been met on. Particularly, there are large divergences on the mechanism exploration of it.This thesis focused on dynamic strength of aluminum alloy, through testing the performances under static and dynamic load, simulating the experiment on computer, and analyzing the variation of each physical element, means to find out the truth of material dynamic strength. The comparison of static and dynamic experiment results shows that the stress curve under dynamic load is waving around the static stress curve, larger fluctuation on the upward section of dynamic load and smaller on the flat section. And it approximates to a stable static ultimate strength. The experiment shows that specimens cracked near the stable ultimate strength not at the maximum value of stress, and the failure stress is same as static ultimate strength, which is about 590MPa. As small viscosity effect of metal material itself and little effect on linear experimental structure, the viscosity effect is neglected, so the inertial effect becomes the major investigation under dynamic load. The numerical simulation indicates that the inertial effect offset the ultra high stress, which was up the static stress curve. The waving form of dynamic stress is under the effect of?inertial.Combined with phenomenon of experiment and the numerical simulation, it shows that the inertial effect protected the specimen when its stress exceeds the static stress curve. The specimen did not damage on the largest stress, but around the ultimate strength, for the protection of inertial effect on the upward section and it would become weaken as the decrease of stress-curve's amplitude.