双金属层状板中软界面层对裂纹扩展的影响

Effect of Soft Interphase On the Crack Growth in The Bimetallic Laminate

采用带软界面层的双金属层状板 ,分析了裂纹垂直于界面扩展过程中的力学行为。带单边裂纹的钢 /铝层板的弯曲疲劳实验表明 ,裂尖接近软铝界面层时裂纹扩展速率da dN变化很大 ;裂纹扩展到达界面层时发生偏折。利用有限元软件分析了裂纹尖端前沿应力和应变的变化规律 ,计算结果表明 :软铝界面层出现较大塑性应变 ,增加了裂纹扩展阻力 ,并使裂纹扩展力ΔK减小 ,导致了da dN降低 ,而软界面层中的T应力增高 ,造成裂纹偏折现象。

This paper analyzes the mechanics behavior of crack growth normal to the interface by using the bimetallic laminate with soft interphase. Experiments of steel/aluminium laminate with single edge crack show that the fatigue crack growth rate da/dN is decreased when the crack tip is reached the interface. And the crack deviation will occur in the interphase. The change of the stress and strain in front of the crack is analyzed by use of the finite element software. The calculated results show that larger plastic strain occurs in soft aluminium interphase. So the crack growth resistance is increased, and the crack growth force Δ K is decreased. It leads to the decrement of da/dN. The T-stress in soft interphase is higher relatively. This causes the deviation of crack growth.