刚体碰撞下直杆的塑性屈曲和后屈曲

研究了受刚体轴向碰撞直杆中塑性屈曲变形发展的机理.推导了增量形式的非线性动力方程,并用差分法求解,将特征值分析给出的初始局部屈曲位移作为方程解的初始条件.数值结果说明:随着轴向压缩波的传播,碰撞端附近发生的局部屈曲变形增长和向前传播,由半波形的初始模态发展成后屈曲高阶模态;在后屈曲变形的早期阶段无应变率逆转发生,切线模量理论适用于该阶段弯曲变形的计算.

THE PLASTIC BUCKLING AND POST-BUCKLING OF A BAR IMPACTED AXIALLY BY A RIGID MASS

The mechanism of plastic-buckling deformation evoluation in a bar impacted axially by a rigid mass is investigated.The non-liner dynamic equations in increment form are derived and solved by use of the finite difference method.The initial local-buckling displacement obtained from eigenvalue technique is taken as the initial condition.Numerical results show that,as the axial compression waves propagate,the local buckling deformation near the impacted end grows up and propagates,and the initial buckling mode with half-wave profile will develop into a higher post-buckling mode.No strain rate reversal occurs at the early stage of post-buckling.Thus,the tangent-modulus theory is valid for the calculation of bending deformation at this stage.