| Nowadays,violent conflicts occur frequently in the world.Among all kinds of violent incidents,sharp objects such as knives,nails and iron pieces account for a considerable proportion of personal injuries.Compared with cutting and chopping,sharp objects have greater pressure,stronger penetration and greater harm to human body when piercing fabrics,so it is necessary to study stab-resistant clothing.At present,the research on stab-resistant clothing is generally divided into several categories:hard stab-resistant clothing,semi-hard stab-resistant clothing,flexible stab-resistant clothing and liquid stab-resistant clothing,among which semi-hard stab-resistant clothing has better comprehensive performance and lighter weight on the basis of ensuring stab-resistant performance.This paper discusses the blocking mechanism of the tool,the reverse cutting mechanism of the tool and the downward movement and rotation damping mechanism of the collision particles.The synthetic diamond particles/PI composite resin sheet with gradient particle density layer by layer is designed theoretically,and then the stab-resistant performance of the composite resin sheet with different mass fractions is analyzed to explore the stab-resistant mechanism of the composite resin sheet and the factors affecting the stab-resistant performance of the composite resin sheet,so as to realize the high-efficiency and light-weight stab-resistant effect.Finally,the composite resin sheet is combined with the fabric,so that the semi-rigid stab-resistant clothing has both stab-resistance and comfort,and the following conclusions are obtained:（1）The main mechanisms of the composite resin sheet’s anti-stab function:the cutter blocked by collision,the cutter is cut reversely,and the collision particles move down and rotate and damp,all of which are affected by the diamond particle size,volume fraction,distribution and regularity.The collision probability between tool and diamond particles P is positively correlated with mass fraction f M,volume fraction f V and thickness of resin sheetδ.When the tool is blocked by collision,the probability that the tool blocked by frontal collision with diamond particles P1 is in the range of 14.1%～37.67%,and the sum of the probabilities of bending and skewing P2 due to non-frontal collision with the tool is 1.By characterizing the stab-resistant mechanism of the composite resin sheet,a theoretical model of gradient distribution of particles layer by layer is proposed,which can not only ensure the deflection of the resin sheet,that is,the bending deformation of the resin sheet does not exceed the failure deformation of the resin sheet,but also increase the collision probability P between the cutter and diamond particles in each layer,thus realizing the lightweight and efficient stab-resistant function of the composite resin sheet.At the same time,the composite resin sheet with gradient distribution of particles layer by layer can be quickly dispersed through the flexible layer and consume the energy of tool penetration,which is semi-quantitatively confirmed by the corresponding experimental results.（2）The influence of the introduction of diamond particles and their mass fraction on the stab resistance of the composite resin sheet is investigated.The results show that the introduction of diamond particles can significantly improve the stab resistance of the resin sheet,and with the increase of diamond particle content from 0%to 45%,the stab resistance of resin sheet is gradually enhanced.At the same time,the relationship curve between stab-resistant strength F and volume fraction f V（converted by mass fraction f M）is constructed by fitting the measured data,and the nonlinear correlation between stab-resistant strength F and volume fraction f V is confirmed.Compared with the traditional linear equation,it has an increase of 0.8 power,which proves the existence of the three mechanisms of stab prevention.（3）Gradient distribution of particles layer by layer Composite resin sheets were prepared by stacking diamond particle layers with different mass fractions.And the stab resistance of composite resin sheets with large particle gradient difference is more excellent.The load of cutting tools is positively related to the mass fraction of diamond particles in composite resin sheets,which is qualitatively consistent with the theoretical estimation of the above three mechanisms.（4）When the shape of resin sheet in fabric-synthetic diamond/PI composite resin sheet is regular hexagon,its coverage probability P3 is higher,which is 89.21%for single layer,99.5%for double layer resin sheet,and 100%collision between cutter and resin sheet can be realized for three layers resin sheet.By increasing the penetration depth of the cutter,the introduction of fabric affects the cross-sectional area of the cutter penetration,thus enhancing the stab resistance of the fabric-PI composite resin sheet.At the same time,it is found that the fabric under the resin sheet can significantly improve the stab resistance of the fabric-PI resin sheet laminated structure,which proves that the existence of the flexible layer plays an important role in rapidly diffusing the energy of the knife penetration.It is found that the structure of double-layer resin sheet and double-layer fabric can resist the penetration of the cutter.Compared with the 45%composite resin sheet which can resist the penetration of the cutter,the quality of the resin sheet of the structure of double-layer resin sheet and double-layer fabric is reduced by 14.29%. |
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