| The measurement of residual stress in welded structures is a difficult and hot issue at present.Contour method is a novel widely concerned measurement of residual stress.In this paper,numerical simulation is used to study the theory of contour method.Experimental data which has been measured is used to verify its accuracy.Besides,a novel kind of contour method which combines the theory of eigenstrain and contour method is studied by both finite element simulation and experiment.This method can give a 3-D map of the residual stress in welded structures by one cut.Firstly,the theory of contour method is studied.Relationship between the displacement of cutting surface contour and the residual stress is illustrated.The residual stress can be calculated by reverse deformation of the measured displacement.Secondly,a simulation experiment of contour method has been done,which shows that the contour method can measure a full 2-D map of the residual stress normal to the cross section.Besides,with the existing profile measurement data,the accuracy of the contour method was validated.On the basis of previous research,studied a new kind of contour method,the measured displacement was used to calculate the eigenstrain,and then use the eigenstrain to calculate the residual stress.A simulation experiment of this method was done,and the results were analyzed,the effects of polynomial order has been discussed.Finally,the method was experimentally validated.The processing technology and the way of data processing in the experiment has been discussed.Based on the profile measurement data,the new contour method can give a 3-D map of the residual stress in welded structures.This result were compared with the results of numerical simulation and hole drilling method,which verified the accuracy of this method.The 3-D map of the residual stress in welded structures is difficult to test.Usually,it can only be calculated by numerical simulation.Therefore,the method which combines the theory of eigenstrain and contour method is suitable for both scientific research and engineering application.Plenty theoretical research and verification instructions of contour method were done in this paper.And the theory of eigenstrain was combined with contour method.This paper has a certain degree of innovation and significance in the related field research. |
