A new split Hopkinson tensile bar design

Reinforced thermoplastic structural detail parts and assemblies are being developed to be included in current aeronautic programs. Thermoplastic composite technology intends to achieve improved properties and low cost processes. Welding of detail parts permits to obtain assemblies with weight reduction and cost saving. Currently, joining composite materials is a matter of intense research because traditional joining technologies are not directly transferable to composite structures. Fusion bonding and the use of thermoplastic as hot melt adhesives offer an alternative to mechanical fastening and thermosetting adhesive bonding. Fusion bonding technology, which originated from the thermoplastic polymer industry, has gained a new interest with the introduction of thermoplastic matrix composites, which are currently regarded as candidate for primary aircraft structures. This paper reviewed the state of the art of the welding technologies devised to aerospace industry, including the fields that Universidade Estadual Paulista Julio de Mesquita Filho and Universidade de Sao Paulo are deeply involved.

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A Review of Welding Technologies for Thermoplastic Composites in Aerospace Applications

The tensile strength of unidirectional carbon fiber reinforced plastics under a high strain rate was experimentally investigated. A high-strain-rate test was performed using the tension-type split Hopkinson bar technique. In order to obtain the tensile stress–strain relations, a special fixture was used for the impact tensile specimen. The experimental results demonstrated that the tensile modulus and strength in the longitudinal direction are independent of the strain rate. In contrast, the tensile properties in the transverse direction and the shear properties increase with the strain rate. Moreover, it was observed that the strain-rate dependence of the shear strength is much stronger than that of the transverse strength. The tensile strength of off-axis specimens was measured using an oblique tab, and the experimental results were compared with the tensile strength predicted based on the Tsai–Hill failure criterion. It was concluded that the tensile strength can be characterized quite well using the a...

Tensile strength of unidirectional CFRP laminate under high strain rate

High strain rate tensile behavior of woven fabric E-glass/epoxy composite

国際会議「Fracture Mechanics of Ceramics」に出席して

Dynamic tensile properties of carbon fiber composite based on thermoplastic epoxy resin loaded in matrix-dominant directions

It is well known that the strength of glass fibers increases with increasing strain rate. Consequently, impact strength of glass fiber is competitive with that of carbon fiber. This strengthening phenomenon is well recognized for bulk glass. Strain-rate dependence of the strength for bulk glass was described by considering slow crack growth in glass. The analytical model that considered the slow crack growth of glass is proposed to predict the strength of glass fibers. The proposed model considered the stress corrosion limit and a constant crack velocity region. Calculations showed almost same results with the previous model, however, some differences were confirmed. To discuss the validity of the analysis, tensile tests of E-glass fiber bundles were conducted at various strain rates. It was observed that the fracture behaviors differ with the strain rates. Experimental results showed that the strength of E-glass fibers increased with increasing strain rate. Furthermore, we confirmed that the analytical results were in good agreement with the experimental results. The strain-rate dependence of the strength of glass fibers was successfully predicted by considering the slow crack growth in glass.

Strain-rate dependence of the tensile strength of glass fibers

The tensile properties of E-glass, which is the most popular reinforcement fiber in composite materials, were determined from the experimental results of fiber bundle testing under a high strain rate. The tests were performed by using two types of experimental methods. One is the tension-type split Hopkinson bar system and the other is the universal high-speed tensile-testing machine. In the results, it was demonstrated that the tensile strength and fracture strain of E-glass fiber increased with the strain rate. The absorbed strain energy, therefore, significantly increased. It was also shown that the strain rate dependency of E-glass fiber tensile strength was strongly affected by fiber diameter. The smaller diameter of E-glass fiber has the stronger strain rate dependency. Finally, the impact tensile strengths of high-strength glass and carbon fibers were investigated. It was confirmed that the tensile strength of the high-strength glass fiber also increased with the strain rate, but the tensile proper...

Experimental study on impact tensile property of glass fiber

This study aims to characterize the dynamic tensile strength of unidirectional carbon/epoxy composites. Two different carbon/epoxy composite systems, the unidirectional T700S/2500 and TR50S/modified epoxy, are tested at the static condition and the strain rate of 100 s−1. A high-strain-rate test was performed using a tension-type split Hopkinson bar technique with a specific fixture for specimen. The experimental results demonstrated that both tensile strength increase with strain rate, while the fracture behaviors are quite different. By the use of the rosette analysis and the strain transformation equations, the strain rate effects of material principal directions on tensile strength are investigated. It is experimentally found that the shear strain rate produces the more significant contribution to strain rate effect on dynamic tensile strength. An empirical failure criterion for characterizing the dynamic tensile strength was proposed based on the Hashin's failure criterion. Although the proposed crit...

Norihiko Taniguchi

Papers

Tensile strength of unidirectional CFRP laminate under high strain rate

Dynamic tensile properties of carbon fiber composite based on thermoplastic epoxy resin loaded in matrix-dominant directions

Strain-rate dependence of the tensile strength of glass fibers

Experimental study on impact tensile property of glass fiber

Experimental Characterization of Dynamic Tensile Strength in Unidirectional Carbon/Epoxy Composites