The me-chanics analysis of various BHA's was carried out by gap-element method for the rotaryand directional drilling in the horizontal well,and the characteristics of various BHA'swas evaluated according to the forces of inclination and azimuth at the drilling bit,wh.

Oil tube mechanical analysis based on Double-layer contact gap element;

Calculate and analysis of fatigue life with principle of the gap element;

In view of existing situation of the extended-reach wells (ERW), a new mechanics model for the torque and drag calculation of the whole drill-sting is established with gap element method in extended reach wells and it considers for drilling fluid, contact friction and local bending of drilling-string.

On influence of interstitial elements on Ti-Al liquidus;

These methods are following as:alloying,grain refinement,heat treatment,control of the interstitial elements,etc.

According to the“Average Lattice”models of the empirical electron theory of solids and molecules,the effects of interstitial impurities on valence electron structure of intermediate phase are analyzed,the effects of interstitial impurities on some phase transformation in intermediate Ti-Al alloys are discussed.

Jack-gap element model for numerical simulation of removing temporary supports of large-span steel structural roof;