Study On Damage Of The Composite Barrel

In shot process, Composite barrel comes under propellant gas with high temperature and high pressure pulse style high speed impact, the projectile packed into action, cartridge belt guiding turns action, and axial tension action of the recoil mechanism. Poor working conditions easily lead to a composite barrel failure because of micro defects evolution, fatigue and overload, cause incalculable loss of life and property. This paper combined with the latest research achievements at home and abroad about the composite barrel, by dint of advanced calculation technology, analysis methods and means of simulation, conducted a systematic comprehensive analysis about the damage problem of composite barrel, and acquired some useful conclusions. Above of these provide strong theoretical guidance and technical support for composite materials in the application of gun tube how to reduce injury, avoid risks, life forecast.The contents and conclusions of this paper are embodied in the following aspects:(1) Damage modes in composite materials including matrix cracking, delamination, interface debonding, fiber fracture, fiber pullout, matrix yielding and so on, according to the different damage mode of materials, combining different loads, corresponding strength failure criterion is established; Based on continuum damage mechanics theory and method, according to the characteristics of structure and material composition in the composite barrel, using irreversible thermodynamics, introducing damage variable, the elastic-plastic isotropic and anisotropic damage model are proposed to predict the progressive failure properties of the carbon fiber reinforced composite material barrel; Damage as part of a micro structure property is introduced to the continuous medium model and the damage evolution law is used to describe defect’s formation, expansion and the polymerization process.(2) Study on the static, dynamic mechanical properties of the composite barrel is based on the mechanical constitutive model, laminated composite is a multicomponent anisotropic materials, this paper describes the micro damage distribution inside the materials, generalized damage force is used to describe the distinctive nature of the impact of micro defects; Based on continuum damage mechanics, damage constitutive model and damage evolution equation of the composite barrel are established; by using the energy method, function of damage and fatigue life is derived; by using nonlinear finite element analysis software ABQUS, the whole damage process of the composite tube with a metal liner under static load and fatigue load loading are simulated separately, damage mode and damage mechanism of the composite tube is analyzed, and the law of energy dissipation in the process of structure damage is expounded.(3) Damage initiation in the composite barrel under complex stress state mainly is the crack initiation and growth, matrix cracking and fiber breakage, then damage extension in the subsequent loading. Based on the theory and concept of fracture mechanics, considering three different load boundary conditions, using the energy method, crack dynamic, static expansion model and the fatigue propagation model of the composite tube are respectively deduced, and the crack propagation criterion of the composite tube is upbuilt. Using extended finite element method (XFEM) which is based on linear elastic fracture mechanics, the crack stress intensity factors and the energy release rate are predicted by the constitutive relation, combined with the effective stress intensity factor and crack propagation criterion the crack displacement vector function is established, modeling and simulation calculation are implemented by using software ABAQUS, crack propagation problem in the tube under static loading, impact loading and fatigue loading were studied separately, the different effects on the composite barrel damage about the initial crack location have been compared and studied, the damage characteristics quality about the all steel barrel and composite barrel have been compared, propagation law of crack in the composite barrel is acquired.(4) Starting from the generation and propagation mechanism of stress wave, combined with the orthotropic materials and multiple characteristics of the composite barrel, the finite element differential equations for the propagation of stress wave and the expression of stress wave propagation velocity in the composite barrel of are deduced within the cylindrical coordinate system. By using dynamic finite element analysis software LS-DYNA, modeling and simulation analysis of the simplified model of composite barrel under mobile inner pressure load is carried out, the dynamic analysis about composite barrel reveals the law of stress and strain amplitude development when the pressure front move along the axial of the barrel, and the resonance effect come with propagation of stress wave. The material properties at high temperature decrease rapidly because of the low shear and tensile strength at the interface of multi-material laminated structure and loading rate dependence in polymer on composite material properties, so the damage propagation of composite barrel caused by the stress wave is more deadly.(5) The impact response of experimental research is implemented, dynamic fracture parameters of the fiber reinforced composite material and steel material in the damage initiation, evolution, expansion whole process are obtained; Taking the simplified model of composite barrel as the object of study to carry out mechanical simulation experiment, the interactive law of damage process between different internal pressure impact load and damage mode is studied, and the rationality and validity of the numerical simulation model is verified.