Deck Structure Analysis Under Undercarriage Load

With the military's development,weapons and military equipments' rapid transport by warship in today's military combat is particularly important.Different equipments act on the ship deck in different ways,and some large-scale special equipments rest on the ship deck through undercarridges made by metal.Each undercarriage holds great weight,so analyzing its effect on the deck structures accurately is essential.The effect of metal undercarriage on deck structures differ from that of wheels,and can't be calculated simply with the uniform load,as it relates to stiffness.Generally speaking,regions with different stiffness withstand different forces.Structures with large rigidity like longitudinals and transverses are sure to withstand greater force than the deck plates,so deck structure under undercarriage load must be calculated by nonlinear contact analysis.Nowadays,study on deck structure under this load is few and there is no other relevant specifications offered,so it is very necessary to carry on research on the ship nonlinear contact analysis.Firstly,structural modeling,load calculation and contact surfaces selection are studied in the paper.Then,in the following sections,the paper carryes on nonlinear contact analysis on longitudinals,deck plates,through a variety of conditions respectively.Using contact force information obtained from nonlinear contact analysis,the formation ideas and corresponding structures load calculation formula is proposed,and verified by means of linear elastic analysis.The paper also puts forward the corresponding simplified calculation method for each structure under undercarriage load.The law of load on transverse is obtained by nonlinear contact calculations and linear elastic analysis,combined with equivalent method.Structure analysis of deck under undercarriage load shows that,when the undercarriage length and longitudinal span is nearly equal,the contact force of longitudinals and deck plates can be calculated by three forces balance.For longitudinal analysis,the condition that the fore of undercarriage reaches the 2/3 of longitudinal span,is the dangerous working conditions(with the max stress),and for deck plates analysis,while the distance between the fore of undercarriage and transverse is 1/3 of longitudinal spacing,is the most dangerous condition(not affected by boundary).When longitudinal span is much larger than the undercarriage length,condition with undercarriage between transverses is the most dangerous conditions for both longitudinals and deck plates analysis,and contact forces can be calculated by the relevant formulas.For the transverses analysis,the load on the transverse can be calculated by displacement equivalent.When undercarriage is between longitudinals in the cross-sectional direction,on the transverse in the longitudinal direction,the load on the transverse reaches the max.Furthermore the larger transverse spacing is,the larger the load on the transverse is.