不同侧限及荷载比例工况下泡沫金属冲击性能研究

泡沫金属在实际工程中往往承受复杂多轴加载工况,且受到突发性爆破等极端动荷载的影响,处于多轴动态复杂应力状态。目前,受实验条件限制,泡沫金属难以实现任意比例的真三轴动态实验。本文采用数值模拟方法,采用霍普金森杆和解析刚体,分别施加冲击荷载和侧限荷载,实现了泡沫金属真三轴动态实验,且实验过程中满足应力均匀性条件,同时,探究了不同侧限条件和侧向预压力比例对泡沫金属多轴冲击性能的影响。结果表明:沿着冲击方向施加2 MPa的预压力对应力幅值为200 MPa的梯形应力波双向冲击的泡沫金属冲击性能无明显影响;侧限约束的增强能提高泡沫金属抗冲击承载能力;当冲击变形模式主导胞孔结构变形时,泡沫金属三向预压力比例对其抗冲击能力无明显影响。

Study on Impact Properties of Metallic Foams Under Different Lateral Restraints and Load Proportions

Metallic foams usually sustain multiaxial and dynamic loadings in applications,which are in multiaxial dynamic complex stress state affected by extreme dynamic loads such as sudden explosion.With limitations of experiments, multiaxial dynamic experiments with variable stress triaxiality are difficult to be realized. In this paper, the true triaxial dynamic experiment of metal foam is carried out by using numerical simulation method, using Hopkinson bar and analytical rigid body to apply impact load and lateral restraints respectively. In addition, the stress uniformity condition was satisfied during the experiment. At the same time, the influence of different lateral confinement conditions and the ratio of lateral prestressing force on the multi-axial impact performance of metal foam was investigated.Results indicated that the pre-pressure with 2 MPa in the impact direction has no significant effect on impact properties of metallic foams under bidirectional impact loading with the stress amplitude of 200 MPa. The impact supportability was improved with the enhancement of lateral restraints. The stress triaxiality of pre-pressure has unremarkable influence of impact performances when cells'' structures deformations are dominated by the impact deformation model.