LY12/Cu双金属层合板的疲劳性能(Ⅰ)——面裂纹

Fatigue crack propagation in LY12/Cu double-layer metal laminate(Ⅰ)──Face-crack

考察了爆炸复合层状双金属板LY12 /Cu界面两侧材料弹塑性失配对面裂纹疲劳扩展行为的影响。结果表明 ,界面两侧材料的弹塑性失配对复合板面裂纹的扩展驱动力具有重要影响。当裂纹由弹性模量、屈服强度高的一侧向低的一侧扩展时 ,实际驱动力大于外加名义值 ;当裂纹由弹性模量、屈服强度低的一侧向高的一侧扩展时实际驱动力小于外加名义值 ,从而造成裂纹扩展的加速或止裂 ,其影响离界面越近效果越显著。但弹性失配在裂纹开始扩展直至界面的整个过程都起作用 ,而强度失配只在裂尖距界面一定距离内 (Rp)

The fatigue face-crack growth behavior in explosive bonded double-layer metal composite plate (LY12/Cu) was investigated. The results indicate that, the elastic-plastic mismatch of components has significant influence on the near-tip 'driving force' of fatigue crack growth. It is demonstrated that the crack-tip is 'shielded' from the remote loads when it approaches the interface from the weaker material whose yielding strength and elastic module are lower. And the effective 'driving force' at the crack tip is greater than the remote loads when it approaches the interface from the stronger material whose yielding strength and elastic module are higher. The shielding and amplification of the near-tip 'driving force' from the components' elastic-plastic mismatch are more and more obvious with the crack-tip approaching the interface. However, the ranges of elastic mismatch and plastic mismatch taking effect are not the same. The elastic mismatch acts from the fatigue crack starting growth to crack-tip contacting interface, the plastic mismatch only acts after the crack-tip plastic zone contacting the interface.