Ballistic impact simulation of Kevlar-129 fiber reinforced composite material

The penetration resistance of Kevlar-129 fiber reinforced composite materials was investigated with AUTODYN software.The ballistic limits of the fragment that pierced 6kinds of target plates were obtained by finite element simulation when the 10 g fragment simulation projectile（FSP）impacting to the target plates of different thickness values of 8,10,12,14,16 and 18mm with appropriate velocity,respectively,and the influences of thickness on the ballistic limits and the specific energy absorption were analyzed.The results show that the ballistic limit of Kevlar-129 fiber reinforced composite plates presents linear growth with the increase of the target thickness in the range from 8to 18 mm.The specific energy absorption of plates presents approximately linear growth,but there is slightly slow growth in the range from 10 to 16mm of the target thickness.It also can be found that the influences of plate thickness and surface density on the varying pattern of specific energy absorption are almost the same.Therefore,both of them can be used to characterize the variation of specific energy absorption under the impact of the FSP fragment.

AN EXPERIMENTAL STUDY ON POST-BUCKLING BEHAVIOR OF SLENDER COLUMN WITH FIBER REINFORCED COMPOSITE MATERIAL

Equilibrium paths of post-buckling are measured for large slenderness column specimens made of the fiber reinforced composite material. The influence of the initial curvature is investigated experimentally and compared with the result of the initial post-buckling theory. Both the theoretical and experimental results reveal that the column with the initial curvature has stable post-buckling behaviors and is not sensitive to the imperfection in the form of initial curvature. The experimental results show that when the lateral buckling displacement is less than 20 percent of the column length, the experimental results agree with the results from the theory of initial post-buckling quite well, while they agree with the results from the large deflection theory in a quite large range.

The impact of the new composite material technology on the performance of the tennis rackets

With the continues improving of people＇s living standards, more and more people work out in all kinds of sports fields beyond the busy work. On the other hand, the development of the modem competitive sports also requires that the sports experts should not only strive for the scientific training, but should also pay much attention on the improvement and development of the sports equipment at the same time, which makes the sports equipment market have achieved unprecedented prosperity. This paper introduces the application of the fiber reinforced composite materials in the field of sports equipment, which is described mainly from the advantages of the fiber reinforced composite materials used in sports equipment areas, and from the aspects of the principles of material selection, the product varieties, the application examples and the status.

Research on the Crack Detection of Conductive Components Using Pulsed Eddy Current Thermography

Crack of conductive component is one of the biggest threats to daily production. In order to detect the crack on conductive component,the pulsed eddy current thermography models were built according to different materials with the cracks based on finite element method(FEM) simulation. The influence of the induction heating temperature distribution with the different defect depths were simulated for the carbon fiber reinforced plastic(CFRP) materials and general metal materials. The grey value of image sequence was extracted to analyze its relationship with the depth of crack. Simulative and experimental results show that in the carbon fiber reinforced composite materials,the bigger depth of the crack is,the larger temperature rise of the crack during the heating phase is; and the bigger depth of the crack is,the faster the cooling rate of the crack during the cooling phase is. In general metal materials,the smaller depth of the crack is,the lager temperature rise of the crack during the heating phase is; and the smaller depth of the crack is,the faster the cooling rate of crack during the cooling phase is.

Damage detection method in complicated beams with varying flexural stiffness

A damage detection method for complicated beam-like structures is proposed based on the subsection strain energy method （SSEM）, and its applicability condition is introduced. For a beam with the continuously varying fiexural stiffness and an edge crack, the SSEM is used to detect the crack location effectively by numerical modal shapes. As a complicated beam, the glass fiber-reinforced composite model of a wind turbine blade is studied based on an experimental modal analysis. The SSEM is used to calculate the damage index from the measured modal parameters and locate the damage position in the blade model successfully. The results indicate that the SSEM based on the modal shapes can be used to detect the damages in complicated beams or beam-like structures for engineering applications.