backer,stone shingle

The experiments of percussive penetration into rock plates at low velocities were made.

实验表明:石板在冲击凿入时主要产生径向裂纹和锥形裂纹,径向裂纹由侵入点的背面向外向正面发展,锥形裂纹由冲击点向背面发展;径向裂纹主要是由局部挠曲产生的,锥形裂纹是由赫兹接触拉应力产生的。