Based on analysis of factors influenced the drill string falling speed in the wellbore ,this paper establishes the mathematical moving model of free falling string in the wellbore,and discusses the collision force when the drill string falls down to the bottomhole.

The max collision force of ship-bridge collision is one of the most important factors for bridge design.

The comparative study of collision characteristic between bow structures with transverse frames and bow structures without transverse frames was developed by using of the nonlinear finite element program MSC/DYTRAN for realizing the effects that transverse frame act to damage mode, collision force of ship bow structures and energy dissipation.

Then the formula of the impact force and contact time was induced,which the elastic coefficient of restitution was considered in contact time calculation.

Based on the dynamic model,the relationship between the ball screw rotational speed,impingement angle,impact force and contact time is analyzed.

For bridge impacted by 5000DWT ship as an example,the impact forces are calculated by some different calculation methods provided in some home and abroad codes and the substructure of bridge acted by these impact forces is analyzed by finite element method.

The slant hole lane track transportation race car occupies the very important status in the coal mine production and transportation,it can simulate the impact process of tramcar and it s defend installation via simulink simulation,find the change rule of the impact power which changes with the tramcar mass and speed,so that to design in reason much more.

The slant hole lane track transportation race car occupies the very important status in the coal mine production and transportation,it can simulate the impact process of tramcar and it s defend installation via Simulink simulation,find a change rule of the impact power which changes with the tramcar mass and speed,so that to design in reason much more.

The calculation equation of impact reverse force vector is obtained when the existence of departure between strike place of hammer of crusher and impact center based on the theory of mechanics.

Experimental study on pressure collisional broadenings of ultraviolet absorption cross-sections of nitric oxide at high temperature;

The impact pressure produced by explosive detonation is essential condition of the base plate and cladding plate coalescence for metal explosion welding.

The transient impact pressures on substrate surface after impact are calculated for different droplet conditions.

Basic conceptions of dynamical breakage and methods of impact testing of rock are introduced,different pills and impact pressure are studied,stress and strain in impact testing are measured,and some benefit conclusions are gived.