Research On The Standardization Of Low Velocity Impact Test Of Textile And Composites

In recent years, research on the development of impact protective equipment seems to be quite important due to that the impact happens frequently as the main form of the personal safety accident frequency like falling objects, traffic accident, etc. Traditional impact testing equipment limited to detect damage or destroy the relevant indicators of the impact of the material itself, which is impossible to meet the related test for the purpose of human body protection. Thus, Shanghai University of Engineering Science, cooperated with Laizhou electronic instrument co., LTD, developed SHLJ LSIT- 01 type low speed impact tester. This instrument can be used for the impact detection of those based on the protective effect of being the object of protection through the protective material after impact. However, the tester is still at the stage of preliminary commercialization after the success of R & D, relevant indicators and test methods to detect no clear conclusion, an urgent need to develop a relatively scientific and reasonable standardized test method and test the depth of the development of related indicators.This topic based on developed standardized test methods for various materials, from the test conditions, the sample classification, develop options, auxiliary materials testing methods carried out, a total of four large number of theoretical and experimental demonstration, and studied the relationship between compression performance and impact protection performance of warp-knitted spacer fabric impact protection performance by using the developed test methods.The main contents of this paper cover the following four aspects.(1) Impact protection test of six major inspection index were put forward for the new impact protection testing equipment, such as “the remaining impact load”, ”impact acceleration peak value”, “peak duration”, “material damage condition”, “the system energy absorption” and “the material energy absorption”, these six major inspection index can used as detections to characterize the impact of shock isolation protection capabilities for protective materials.(2) For the purpose of standardized testing, the relationship between sample size, silicone mats changes and the remaining impact load had been researched. The results showed that increase or decrease the size of flexible materials has little impact on the remaining impact load, it has great impact on the remaining impact load when come to the rigid materials and the remaining impact load value change trend mitigation when the size increase to 10 cm. So, the test sample size is defined as a square of side length 10 cm for ease of experimental manipulation. Silicone mat layers increase or decrease and the size change have an impact on the remaining impact load, but it will not have a material impact on the results for comparative trials. For the purpose of protection of the sensor, the impact test should add at least one side length of 12 cm square silicone mat.(3) Based on the cluster analysis of SPSS, textiles and composite materials were classified according to their low speed impact properties. Textiles were divided into two categories, the first category is 2-D textiles includes woven fabric, knitted fabric and non-woven fabric, the second category is 3-D textiles includes multilayer woven fabric, multi-layer knitted fabric, multi-layer non-woven fabrics, wool felt and warp-knitted spacer fabric. composite materials were divided into two categories, the first category includes rigid composite material and double rigid surface laminated composite materials, the second category includes flexible composite material and double laminated composite flexible surface, the third category includes single soft(rigid) surfacing composites. The formulation process-related test methods could be optimized by clustering analysis. A solution based on the impact of various types of materials testing is proposed to solve problems through experiments verify the accuracy and reasonableness, and developed test method which is suitable for all kinds of textiles and composites by category.(4) Studied the relationship between compression performance and impact protection performance of warp-knitted spacer fabric impact protection performance based on the standardized tests. Low-impact protection performance relates to compression performance, the sample parameters of the compression process can effectively predict the residual value of the impact load according to Multiple linear regression model. Found that, in general, lower speed under small elastic modulus material impact protection capability is good, good speed than the elastic modulus of the material under impact protection, can not order the elastic modulus of the material or plastic compression performance to determine material impact protection capability is good or bad alone through the establishment of the impact energy absorption model. There is a residual value equivalent to the same impact speed between the fabric with small elastic modulus, low high plastic compression phase and long duration and the fabric with large elastic modulus, high plastic compression phase, when the impact speed is lower than the speed, low elastic modulus material remaining impact load value is small, the speed is higher than the modulus of elasticity of the material remaining impact load a small value, we can improve its low velocity impact protection capability by appropriate transformation material compression characteristics.