Research on the last impacting velocity of the piston of pneumatic DTH hammer by FEM;

In order to understand the properties of impact toughness of coal with different impact speeds and the change of impact toughness of lump coal to joint directivity of lump coal.

As the jet approaches the surface of road,the impact speed and pressure at staff point are the max.

In order to understand the properties of impact toughness of frozen soil with different impact speeds, and the strength of frozen soil under high strain rates, a series of notched Charpy bar impact tests are conducted on frozen Lanzhou loess, Lanzhou sand, and pure ice with different impact speeds and temperatures.

The formula of impact velocity,impact forces of the ball mediums is extracted.

The relations of erosive ratio to impact time, impact angle,and impact velocity are revealed,the formula of erosive relation is also quantitatively deduced.

A formula for calculating dynamic stress intensity factor of three-poi n t bending specimen is obtained by taking the impact velocity effect on dynamic s tress intensity factor into account.

Through the data of impulsive load experiment on this fuel assembly,this paper obtained how the impact force and impact acceleration changed with time and other parameters,and analyzed the causation of the different impact force and impact acceleration,further more,found the disciplinarian of impulsive load.

First, the primary parameters included maximal acceleration and its pulse width which mainly affect the collimator’s intensity are established in the basis of impact acceleration’s analysis from the time domain and frequency.

This paper discusses the protection of firefighter’s helmet from impact acceleration.

This paper researched the test system of impact deceleration based on the virtual instrument technology,gave detailed exposition of its function,composition,theory and applications.