刚体撞击柔体冲击力问题

zhanggqi

刚体撞击柔体，接触时间很短，刚体K无穷大，变形X无穷小，那请问冲击力怎么得来的呢？

flying27829

根据能量算

fafa6733204

接触力。在STEP里面定义输出

zhanggqi

flying27829 发表于 2012-5-26 13:23
根据能量算

一篇论文里关于柔体撞击是用以下内容的，那刚体撞击的时候，这个方法应该就不成立了？

To assess whether dynamic shear actions are critical,
the duration of initial shear wave propagation must be
compared with the duration taken for the full impact
load to be developed. The duration of initial shear wave
propagation (in the order of 1–2 ms) can be estimated
by dividing the distance of shear wave travel (which is
measured from the point of impact to the column support
points) by the shear wave velocity of concrete. The
shear wave velocity is defined as
√
μ/ρ where μ is the
dynamic shear modulus and ρ is the density of concrete.
Given that the frontal stiffness of the impacting vehicle is
only about K = 1,500 kN/m (W° agstr ¨om et al., 2004), the
shortening of the “frontal spring” in the initial 1–2ms of
impact could not possibly develop any significant impact
force nor direct shear actions onto the column (Figure 3).
The full impact force requires a much longer duration of
40–50 ms to develop. The 40–50 ms duration can be estimated
from the quarter cycle time (T/4) of impact where
T can be expressed as T = 2π

(1000kg)/(1500kN/m)
based on treating the vehicle and the frontal spring as an
equivalent single-degree-of-freedom system. Dynamic
shear phenomenon could have been an issue had the
impacting object been a very hard object in which case
the column could be subject to a phenomenally highimpact
force when initial contact was made with the
object. In other words, the frontal spring of the vehicle
acts as a cushion that defuses the dynamic shear actions.