Research On Stress Wave Transport Of Textile Composites Under Low Velocity Impact And Design Improvement Of Low Speed Impacting Tester

Accidents,falling objects wounding and mechanical impact accidents during project implementation appearing frequently,which causing people to sort of low-impact protection more urgent needs of increasingly demanding.From the existing literature,at present,most scholars experimental study focused primarily on low-impact action process,the composite material itself on the impact energy absorption and material damage,damage mechanisms,and to prevent or slow down the material damage,damage method;in addition,some studies covering textile composite in the case of damage or breakdown of the material for energy absorption,deflection qualitative changes in the situation.And for textile composites by low-speed impact energy transfer cases and applications such as textile composite body from low-velocity impact damage protection no in-depth research,especially the back of protective material impact on the actual impact of the human body no feasible extent testing and evaluation methods.Protective materials under impact loading energy absorption,transmission is very important for protection of human exposure to low-velocity impact damage.In this paper,textiles and other low-speed impact energy absorbing composite materials starting with the delivery aspect,built low-impact stress wave load test platform which consisting of impact loading systems,signal amplifiers,data acquisition systems,etc.optional Plexiglass panels,resin,respectively,and carbon fiber,basalt,ultra-high molecular weight polyethylene(UHMWPE)unidirectional cloth or woven fabric composite material composed of different textile composite sample by impact test to detect,analyze the impact of different parts of the stress wave sensor samples obtained peak value,peak time spacing and impact stress wave propagation rate;Using ANSYS software for low-impact phenomena finite element numerical simulation to explore the impact stress wave propagation within the different textile composites;Finally,the impact of early low defect test platform,participated in the new low-speed impact tester design and development,carried out on the impact of the bullet positioning clamping mechanism,impact load platform,part of the design speed agencies,security systems,improvement,assembly work,focusing on gun body chaired the selection,design and commissioning.The above study will textile composites in body protection,precision instruments of protection and other aspects of the application must provide theoretical support,product development and protection of the practical impact of low practical significance.In this paper,the content and the results achieved mainly involves the following four areas:(1)Simple low impact on the self-built stress wave test platform,made of carbon fiber,basalt fiber,UHMWPE three different performance reinforcing fibers bonded composite made of Plexiglass plate textile composite material impact experiments in free fall height 100mm Next,test and analysis of the impact energy transfer relationship with time,transmission speed,etc.In order to analyze the plane stress wave propagation.Trial found that the amplitude of the low-speed impact of fiber-reinforced composites with stress wave attenuation was a trend away from the point of impact;closest to the impact point,the initial carbon fiber woven fabric reinforced composite stress wave maximum transfer rate;while away from the point of impact Department,the stress wave propagation rate UHMWPE woven fabric largest,with better lateral stress wave propagation properties;but UHMWPE unidirectional fabric minimal stress wave propagation rate,the maximum absorption of the impact energy.And three types of high-performance fibers,UHMWPE fiber-reinforced composite material stress wave propagation fastest.The integrated,low-impact resistant UHMWPE unidirectional fabric material selection is more appropriate.(2)Based on ANSYS/LS-DYNA software simulation parameters to simulate the specimen,found a central location in the sample by the impact of the bullet,the stress from the point of impact to the surrounding radially pass,descending gradually changing stress;this test materials,the center position when the material impact of the bullet impact,first and gradually increase the lead to strain at the edge of the material;drawn impact head speed and acceleration curve by numerical simulation and the actual speed test and impact test acceleration analyzed.(3)Institute to expand testing to achieve the above goals must experiment to investigate the impact of the original low-speed tester to improve the design.I chaired the selection and design speed agencies involved in the door rack,shock warhead positioning clamping mechanism,impact load platform designed security system improvements,assembly and commissioning.Doors made of steel wire rack surface protection improvement program,the impact of delayed clamping scheme Slow warhead positioning clamping mechanism,the impact of controllable load platform lift improvement program,through various efforts,ultimately successful implementation to solve the corresponding problem.(4)By comparing the various speed programs,screening,and ultimately selected the reflection speed fiber optic sensor solutions to achieve a low-speed impact tester accurately.Speed mechanism can detect impact head impact velocity and instantaneous velocity rally in front of the sample,in order to characterize the impact of the total energy and bounce energy.Test speed mechanism design error can be controlled within the range of 2%.