originated in the United States, first appeared in the 1950s in the United States military equipment. It is a special car compartment that is organically combined together with a variety of sturdy materials to form a convenient, movable whole.
Military shelters mainly by the front and rear left and right side panels, roof, and floor composition, aluminum as the inner and outer skin, between the steel skeleton with a buried plate fixed cabin equipment. Military shelters
complex structure, the impact of certain structures on Military shelters overall stress and deformation is very small, but it will reduce the computational efficiency of the computer.
Military shelters components of many and complex, some structural components of the entire Military shelters stress and deformation of the impact is very small, but it will largely affect the complexity of the computer-related problem solving and modeling. So before we study Military shelters, we need to simplify the model of Military shelters at the modeling stage. This article does not affect the accuracy of the calculation on the basis of the need to simplify the model, assuming the following：
1) Military shelters skeleton by welding into one, welding material properties can be considered with the adjacent structural parts of the same material properties;
2) Military shelters deformation is a small deformation, there is no relative sliding between the skin and the sandwich, the various structural components to each other, the contact surface of the adhesive strength is sufficient, separation, the debonding phenomenon does not occur;
3) Military shelters each structural member is connected by bolts, rivets, these connections need to contact, extrusion and other non-linear solution can know the force and force transmission situation. The Military shelters itself is a large structure, the above connections are many and complex, it is not realistic to solve, this article can be simplified;
4) the insulation boards, all kinds of holes, and their edging in the Military shelters interlayer can be ignored, irrespective of their influence on the rigidity and strength of Military shelters
5) ignore the corner pieces, that is, three Military shelters large plate intersects the angle, can be used to connect the three large plates. At the same time the connection of two large plate side beams, which can be equivalent to 1 beam.