In the present work, similar thickness laser welded blanks (LWBs) and dissimilar thickness laser welded tailored blanks (LWTBs) of extra deep drawing (EDD) steels were fabricated and these were stretch formed by a 50 mm diameter hemispherical punch under lubricated condition. All these stretch-formed domes were manufactured keeping a consistent combined geometry of hemispherical and conical sections. Subsequently, these domes were crushed quasi-statically and the modes of collapse, load-displacement response, mean crushing load and energy absorption were comprehensively investigated both experimentally and numerically to get insight into the effect of weld zone (WZ), thickness ratio, deformation speed, forming histories and material anisotropy. During all the crushing tests, three similar collapse modes were observed and these were identified as flattening of hemispherical section, inward dimpling of hemispherical section and lastly the flattening of conical section. However, an additional collapse mode consisting of two asymmetrical lobes across the WZ with a stationary plastic hinge was identified in case of stretch-formed domes of LWTBs. It was concluded that the mode of collapse was predominantly affected by the presence of thickness ratio. On the other hand, the mean crushing load and energy absorption capacity were enhanced due to the presence of WZ and the selection of thickness combination. The energy absorption effectiveness factor of LWBs and LWTBs were estimated to be 1.33 to 2.75 times higher than that of monolithic EDD steel. It was further suggested through numerical modeling that the incorporation of strain rate, material anisotropy and forming histories such as non-uniform thickness and strain distributions along with WZ properties improved the prediction of modes of collapse, load-displacement response and mean crushing load.

在目前的工作中，制造了类似厚度的激光焊接毛坯（LWBs）和超深冲（EDD）钢的不同厚度的激光焊接定制毛坯（LWTBs），并在润滑条件下通过直径为50 mm的半球形冲头将它们拉伸成型。所有这些拉伸成形的穹顶均经过制造，保持了半球形和圆锥形截面的一致组合几何形状。随后，对这些穹顶进行了准静态破碎，并通过实验和数值研究了塌陷，载荷-位移响应，平均破碎载荷和能量吸收的模式，以深入了解焊接区（WZ），厚度比，变形的影响。速度，形成历史和材料各向异性。在所有压碎测试中 观察到三种类似的塌陷模式，它们被确定为半球形截面的展平，半球形截面的向内凹陷以及最后圆锥形展平。但是，在LWTB的拉伸圆顶形情况下，确定了由WZ上两个不对称凸角组成的附加塌陷模式，并带有固定的塑料铰链。结论是，塌陷的方式主要受厚度比的影响。另一方面，由于WZ的存在和厚度组合的选择，平均破碎载荷和能量吸收能力得到了提高。LWBs和LWTBs的能量吸收效率系数估计为整体式EDD钢的1.33至2.75倍。