Research On Dynamic Propagating Crack Tip Field And Load Parameter In Viscoelastic Material

A study on the field of dynamic propagating crack tip has vital significance to the material fracture destruction research,while the time-dependent mechanical properties of material have tremendous influence on the rigidity ,the intensity and the service life of the structure.At the sime time,the application of load parameter of the crack tip is extremely widespread in charactizing the crack tip properties. Based on these,this article studied the problems of dynamic propagating crack in the viscoelastic material,which has time-dependent deformation characteristic.The dynamic propagating crack in incompressible viscoelastic material is detailedly studied under the plane strain condition firstly.Embarking from the fundamental equation,combining with the analysis on the singularity of crack tip fields,the asymptotic governing equations are deduced.With soluting-deterimining conditions,the stress,strain and displacement fields near the tip of mode I and II crack are obtained by using the shooting method.The laws of crack tip fields along with variational each parameter are disussed.By comparing with other results,the accuracy of the obtained outcome is demonstrated. Secondly, the dynamic propagating crack tip fields in compressible viscoelastic material for mode I and II are studied,while the analysis is similar to the first step.The rules of fields along with parmeters are debated also.When the Poisson's ratio v is equal to 0.5,the results can completely degenerate to those in incompressible situation,so the validity of the results in compressible situation is verified. Finally, for the crack tip load parameter C^* integral, by its definition and the analysis of singularity, the path-dependent properties are investigated; Using the crack tip fields in incompressible situation,the regularity of C^* can be reflected by a solvable value A₁, accordingly the variations along with each parameter is acquired. The solution of crack tip fields and the rules of load parameter obtained in this paper will provide theoretical reference for further research and the project application of the interrelated problems.