The Research On Prediction Controlling And Effecting Factors Of Hull Plate Frame Welding Deformation

Welding is now the most popular used method to joint steel in ship building.The distortion caused by different kinds of welding methods is inevitable.This distortion not only deduce the the accuracy of the size of the structure that welded,but also increase the cost while building a ship.Equivalent load method based on the inherent strain is the mostly used method to simulate the distortion of a large scale structure.Combined with the welding control method which takes margin into account that is widely used in ship constructing,some discussions are made in this paper:The relation between temperature and inherent strain in welding process is discussed using equivalent load method based on the inherent strain.Combined with finite element theory,a equivalent load calculation formula will be given.then,a longitudinal shrinkage and transverse shrinkage is calculated in ship construction process fillet weld case.The measured results were compared to verify the accuracy of the equivalent load method of welding deformation prediction.Secondly,welding deformation control method that takes margins into account used in ship construction will be discussed in theoretical analysis,traditional empirical formula,and actual measurement to verify the accuracy of the equivalent load method.Based on this,a simulation of fillet weld that takes margins into account is made to prove that it is feasible in controlling the distortion caused by welding.Then,based on the previoous research,a small assembly model is chosen to analyses the effects of welding equivalent load sequence on welding deformation with a creative way of simulating distortion caused by welding process.Based on this,a equivalent load simplified formula and a method of setting up a ship hull distortion caused by welding process data base is given.Finally,though the method used to control distortion,the effect of current,welding speed and thickness on distortion will be discussed,providing a theoretical guiding for the correct selection of current,speed and proper welding method.