不同钢板厚度的脆性断裂力学特征研究

RESEARCH ON MECHANICAL CHARACTERISTICS OF BRITTLE FRACTURE OF STEEL PLATES WITH DIFFERENT THICKNESSES

针对厚钢板强度不足、裂纹敏感性等问题,通过有限元模型构建含缺口尖端的钢板材料,分析不同厚度下钢材缺口尖端应力场分布情况,对钢板脆性断裂倾向进行研究。研究结果表明:在弹性应力阶段,对于50～150 mm的特厚钢板,随钢结构厚度的增加而应力呈现出小幅增长的趋势。沿Z向,σz在缺口尖端取得最大值,靠近裂纹尖端局部区域应力降低并不明显,靠近钢板表面呈直线下降;塑性变形阶段,随着应力水平的增加,特厚板应力衰减速率降低,特厚板的塑性变形受到约束,导致钢板更容易发生脆性破坏。厚钢板的最大拉应力随荷载增加的增幅更为明显,最大拉应力依然在非塑性区且不断增大,最终导致材料发生脆性破坏。

In view of the strength of thick steel plate is insufficient, as wall as the problem of crack sensitivity, using the finite element model to construct the of steel material including cracking tip, the stress field distribution of steel notch tip of steel plates with different thickneses were analyzed and the tendency of brittle fracture of the steel plate were studied. The results showed that in the elastic stress stage, the stress of the 50~150 mm thick steel plate of was increased with the increase of steel structure thickness. Along the z-axis, the maximum value was obtained at the notch tip, the stress reduction in the local area near the crack tip is not obvious, while near the surface of the steel plate decreased linearly. In the plastic deformation stage, with the increase of the stress level, the stress attenuation rate of the extra thick plate decreased, and the plastic deformation of the special plate wa restrained, resulting in the brittle failure of the steel plate. The maximum tensile stress of thick steel plate increased with the increase of load, and the maximum tensile stress was still in the non-plastic zone and increased continuously, resulting in brittle failure of the material.