含缺口受拉平板塑性应力场的有限元分析

含尖缺口受拉平板三维应力场是断裂分析研究中常遇到的问题,进入塑性状态以后,缺口尖端的应力状态和分布与弹性条件下有很大的不同。通过有限元的方法对含缺口受拉平板的塑性应力场进行了分析,并进一步研究了厚度和缺口半径因素对缺口尖端应力场的影响。分析结果表明,缺口半径减小提高了平面内应力σx和σy,也提高厚度方向应力σz和平面应变系数,平面应变系数在塑性条件下趋于0.5;厚度对平面内应力σx和σy影响很小,但提高厚度方向应力σz和平面应变系数,平面应变系数在载荷较小时趋于材料泊松比μ,在载荷较大时趋于0.5。

FEM ANALYSIS FOR PLASTIC STRESS FIELD OF TENSILE FLAT SLAB WITH CRACKLES

The three dimensional elastic stress in the flat slab with crackles subjected to tension is frequently analyzed in mechanics. As entering into plastic stage, the stress status near the crack tip is different with that in elastic stage. This paper analyzes the plastic stress status near the crack tip with the FEA method for the flat slab with crackles in tension, and then discusses the influences of the thickness of the flat slab and crack-tip radius on it. The analytical results show that: (1) the decrease of crack-tip radius increases the stress σx and σy in the plane, the stress σz in the direction of thickness and the plane strain factor as well, (2) the plane strain factor goes to 0.5 in plastic stage, (3) the thickness has little influence on the stress σx and σy in the plane but increases the stress σz in the direction of thickness and the plane strain factor, (4) the plane strain factor goes to the Poisson's ratio under small loading or to 0.5 under large loading.