端末条件を変化させた場合の準静的‐動的負荷速度域における長柱の座屈挙動

抄録

We experimentally investigated the dynamic buckling behavior of long strips in a wide range of loading velocities under three different end conditions; both ends clamped, clamped-supported, and both ends supported. To cover the wide velocity range in our experiments, we used a hydraulic loading device covering the loading velocities from 0.0001 to 0.1 m/s and a free fall drop-weight-type impact-testing device covering the loading velocities from 0.1 to 1 m/s. We chose A7075 aluminum alloy as the target material since it has a very high yield strength (it avoids plastic buckling) and relatively low elastic modulus (resulting in low Euler's buckling load). In the low-velocity range below 0.1 m/s, a dynamic buckling load was measured using a rod-type load cell connected to the piston rod of the hydraulic loading device. In the high-velocity range over 0.1 m/s, a load-sensing block was used to prevent disturbance in the load wave due to wave-reflection and interference. We measured the displacements of long strips using a high-speed magnetic-resistance device. From the relations between the buckling load and loading velocity, we found that there was a minimum velocity where the dynamic buckling load exceeded Euler’s buckling load, and that this velocity was dependent on the end conditions of the specimen and slenderness ratio λ. Based on these experimental results, we propose an empirical formula that can describe the velocity dependence of the dynamic buckling load in the loading-velocity range from 0.0001 to 1 m/s by taking into account various end conditions for long strips.