A Study On The Correlation Between The Typical Failure Mode Of The Strong Dynamic Undercarriage Structure And The Propagation Of The Stress Wave Main And Secondary Waves

Under the action of strong dynamic loads such as explosion and impact,the structure will have different forms of dynamic failure,causing various serious accidents,which will bring great challenges to the protection of weapons and equipment and the safety of infrastructure.Rough lamination failure with inclined fracture under plate impact and oblique crack failure under slip blast loading,as typical dynamic failure modes of structures under strong dynamic loads,bring new challenges to existing theoretical cognition.Dynamic failure occurs in the structure,where the maximum stress in the structure exceeds the material strength,and the stress in the structure propagates in the form of fluctuations.Cognitive structural dynamic failure mode needs to study the corresponding stress,analysis of stress needs to consider the spatio-temporal evolution of stress and strain,and establish the correlation between the propagation of stress waves and the dynamic failure mode of structure,which is helpful to provide ideas for studying failure and improving structural protection technology..Based on the main wave and secondary wave theory of elastic stress waves,this paper discusses the propagation and reflection of stress wave main and secondary waves in structures.The primary and secondary wave theories of elastic stress waves state that the wave equations on volume strain are consistent with existing theories,but a set of wave equations on weak coupling of volume strain and partial strain has been developed.It is revealed that the wave velocities of the primary and secondary waves are consistent with the mechanical behavior of the deformation and stress of the structure.This theory is more consistent with existing experimental phenomena than classical elastic stress wave theory.Aiming at the propagation of the main wave and the secondary wave of the plane stress wave under the impact of the flat plate,the wave boundary conditions of the loading surface and the free plane,as well as the center difference format and iterative format of the wave equation solution,are established.The propagation and reflection process of stress wave main wave and secondary wave is analyzed numerically by the center difference method,and the rough lamination failure mode with oblique fracture is analyzed from the perspective of the structure and stress amplitude of the reflected stress wave,and the dependence of lamination failure and stress wave main wave and secondary wave propagation is discussed.Aiming at the scattering and focusing of plane waves and cylinder waves and the reflection problems of cylinder waves,the corresponding wave boundary conditions of loading surfaces and free surfaces and the center difference format and iteration format of the wave equation solution are established.The scattering and focusing effects of surfaces and the reflection patterns of cylinder waves were analyzed numerically using the center difference method.Among them,the propagation of the cylindrical wave corresponds to the existing experimental results,and the scattering and focusing effects of the surface boundary corresponding to the force wave have a greater impact on the stress and strain state distribution of the reflected wave,and on this basis,the design of the actual engineering structure is provided.A simplified model of slip detonation loading is established,the wave boundary conditions of loading and reflection are established,and the propagation and reflection processes of stress wave primary and secondary waves in the structure are analyzed by the center difference method,and the dependence of oblique crack failure and stress wave propagation under slip detonation loading is discussed.The generation of oblique crack failure is affected by the superposition of stress waves reflected at different times,which is directly related to factors such as detonation speed,loading amplitude and loading pulse width,and is consistent with existing experimental results.