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Research related to stab-resistant armour is focused on developing a low-weight flexible stab-resistant armour. Various materials and methods have been used to reduce the overall bulk but managing the flexibility and bulk with improved stab resistance is still a challenge for the researchers. In this study, flexible stab-resistant material for stab-resistant personal protective equipments (PPEs) has been developed by using shear thickening fluid (STF) treated fabric made of multicomponent yarns and ultra high molecular weight polyethylene (UHMWPE) laminate composite. The stab resistance and comfort behaviour like flexural rigidity and areal density were investigated with respect to number of layers and different STF concentrations according to VPAM KDIW-2004 and respective standards for flexural rigidity. Laminate-Woven hybrid composite was developed to reduce the bulk of the panel while maintaining the required protection level. [ABSTRACT FROM AUTHOR]

Many researchers worldwide have extensively used fibre-reinforced polymer (FRP) strengthening materials to enhance the shear and flexural strengths of reinforced concrete (RC) beams. However, Studies on strengthening of RC beam subjected to combined torsion and bending moment using both spiral and vertical strip configuration of CFRP that explored in this study is rare. This study aims to demonstrate the behaviour of RC beams strengthened with FRP sheets (strips) with different configurations and subjected to combined actions of torsion and bending moment. Eight beams with a dimension of 15 × 25 × 200 cm were cast. One of the beams was not strengthened, but the others were strengthened with carbon FRP. The angle of twist at torque intervals, first cracking torque, ultimate torque and ultimate twist angle of the conventional and strengthened beams during the testing process were compared. Results showed a significant improvement in the torsional performance of RC beams using carbon FRP. The fully wrapped beams performed better than the beams with strip wrapping due to the influence of various wrapping configurations. Amongst the wrapping configurations of FRP fabrics, the 45° spiral strip wrapping configuration was the most effective for RC beam strengthening in terms of torsion resistance. Reinforced concrete (RC) beams strengthened with fiber reinforced polymer composite were tested under combined bending and torsional moment; The effect of composite orientation, spacing and number of plies on the torsional response; Ultimate torsional moments of RC beams; Twist angle of rotation of control and strengthened beams; Analytical prediction for CFRP material contributions to the ultimate torsional moment of strengthened RC beam. [ABSTRACT FROM AUTHOR]

This paper presents the geometry and material distribution influence on energy absorption systems and failure mode of glass epoxy tubes and carbon epoxy tubes in order to improve the structural performances. Experiments were carried out on different types of composite tubes subjected to axial compression load. After collecting the results of the crushing and drawing the load–displacement curve, the initial failure load, maximum crushing load and average load were found. From these parameters, the crashworthiness parameters were calculated. The comparison results between the parameters showed that the best structure of the glass epoxy tubes was the circular tube with eight layers, where produced the highest specific energy absorption at a value of 21.23 kJ/kg. [ABSTRACT FROM AUTHOR]

Lack of post-yield stiffness and corrosion resistance could inevitably result in a considerable loss of seismic performance for steel reinforced concrete (RC) piers. Fibre reinforced polymer (FRP) reinforcement can provide high tensile strength and protection from corrosion. To achieve a better post-yield stiffness and durability for piers, FRP/steel double-reinforced configurations were designed by the proposed flexural-capacity design method. A seismic fragility assessment was also conducted to investigate the effectiveness of design parameters, namely the ultimate tensile strength of FRP reinforcement, elastic modulus of FRP reinforcement, and ratio of steel reinforcement for a double-reinforced configuration to that for a steel RC configuration ( ρ steel / ρ prototype ). The results demonstrated that the FRP/steel double-reinforced piers satisfied the mentioned objectives, while the fragility of these piers was a 30.2% less than that of conventional steel RC piers. A 79.9% higher median PGA at the collapse damage state was achieved, when the elastic modulus of FRP reinforcement changed from 164 to 80.7 GPa. An increase in the median PGA of 34.8% can be achieved along with the increase of the ultimate tensile strength of FRP reinforcement. When ρ steel / ρ prototype was approximately 66%, FRP reinforcement exhibited the highest effectiveness on the seismic performance of piers. [ABSTRACT FROM AUTHOR]

This paper presents an experimental research on timber columns with externally bonded fibre reinforced polymer sheets, which consist of aramid fibre reinforced polymer, carbon fibre reinforced polymer and basalt fibre reinforced polymer. This is to provide a strengthening solution to upgrade the structural behaviour and load carrying capacities of such columns under the influence of fractured wood texture. In total, 14 columns were constructed and tested, consisting of 8 circular timber columns and 6 square ones. Besides, three columns of such two section types with knag were reinforced by wrapping of carbon fibre reinforced polymer sheets and tested. The failure mode was analysed, as well as the fracture surface. Externally bonded fibre reinforced polymer sheets were found to be very effective in upgrading the compressive strength of the columns strengthened. The enhancement on load carrying capacities by fibre reinforced polymer reinforcement is in the range of 69-103% for the specimens with a circular section and of 35-83% for the ones with a square section. The test results also show that better ductile behaviour and higher ultimate load carrying capacities were obtained for the columns with externally reinforcing of fibre reinforced polymer sheets. However, there is a great reduction in ultimate loading capacities on columns with fractured wood texture, and the cracks were found on the fracture surface because of the fibres near the cracks being compressed. [ABSTRACT FROM AUTHOR]

Fibre reinforced polymer is consisted of matrix and reinforcement, which are the deciding factors of mechanical properties. The fibre orientation is dependent on the parameters of material, such as fibre diameter, length, and interaction between fibres (which is interpreted as fibre content), and moulding factors like moulding closure speed, moulding pressure, moulding temperature, etc. Owing to fibre orientation, compression moulded product becomes inhomogeneous and anisotropic, which influences mechanical properties significantly. Therefore, optimal quantitative value of fibre content and orientation is derived to improve tensile strength and shock absorption. Tensile strength of fibre reinforced polymer at 0° orientation is constantly increased along with fibre content and orientation. When fibre orientation is isotropic, tensile strength at 0° direction and the one at 90° direction are same. However, the tensile strength ratio at 90° direction decreases when composite becomes anisotropic ( J is increased). This can be elucidated as the result of the glass fibre filament separation when load is applied perpendicular to the longitudinal direction of filament. Therefore, tensile strength ratio at 90° orientation decreases with fibre content. In conclusion, higher strength can be achieved when fibre used in fibre reinforced polymer is less than the large number of fibres in yarn. [ABSTRACT FROM AUTHOR]

This study is concerned with the experimental investigation into the seismic behaviour and retrofitting of gravity-load-designed reinforced-concrete (RC) shear wall structures in Singapore. These structures are designed according to the British Standard (BS8110 1985). For this purpose, 1/5 scaled models (with and without retrofitting), representing the lower critical regions of a 25-story RC shear wall structure, were tested under cyclic loadings. Test results showed that the shear wall failed at the base due to shear and that the pushover test provides a simplified representation of the cyclic test. Retrofitting the wall with GFRP (glass fibre reinforced polymer) system resulted in improved performances of up to 20% to 30% higher ultimate load capacity and displacement. The study provides an insight into the seismic behaviour of such structures and the mechanism of the proposed retrofitting scheme for improving the structural resistance to seismic loads. [ABSTRACT FROM AUTHOR]