STACKING SEQUENCE OPTIMIZA-TION OF LAMINATED COMPOSITE CYLINDER SHELL FOR MAXIMAL BUCKLING LOAD

A new optimization method for the optimization of stacking of composite glass fiber laminates is developed. The fiber orientation and angle of the layers of the cylindrical shells are sought considering the buckling load. The proposed optimization algorithm applies both finite element analysis and the mode-pursuing sampling （MPS）method. The algorithms suggest the optimal stacking sequence for achieving the maximal buckling load. The procedure is implemented by integrating ANSYS and MATLAB. The stacking sequence designing for the symmetric angle-ply three-layered and five-layered composite cylinder shells is presented to illustrate the optimization process, respectively. Compared with the genetic algorithms, the proposed optimization method is much faster and efficient for composite staking sequence plan.

Design Optimization of CFRP Stacking Sequence Using a Multi-Island Genetic Algorithms Under Low-velocity Impact Loads

A method to improve the low-velocity impact performance of composite laminate is proposed, and a multi-island genetic algorithm is used for the optimization of composite laminate stacking sequence under low-velocity impact loads based on a 2D dynamic impact finite element analysis. Low-velocity impact tests and compression-after impact（CAI） tests have been conducted to verify the effectiveness of optimization method. Experimental results show that the impact damage areas of the optimized laminate have been reduced by 42.1% compared to the baseline specimen, and the residual compression strength has been increased by 10.79%, from baseline specimen 156.97 MPa to optimized 173.91 MPa. The tests result shows that optimization method can effectively enhance the impact performances of the laminate.

Effect of stacking sequence on physical, mechanical and tribological properties of glass-carbon hybrid composites

A study was done to determine the effect of best stacking sequence(position and orientation)on the mechanical properties,friction and wear response of hybrid composites.The main purpose of the study was to determine the best available stacking sequence for which the physical,mechanical and three body abrasive wear rate is optimum.Test for mechanical properties(tensile strength,flexural strength,inter laminar shear strength,impact strength and hardness)was done on glass-carbon hybrid composites.The composites were then subjected to test for three body abrasive wear on a designed experimental setup.Five different factors(sliding velocity,fabric weight percentage,normal load,sliding distance and abrasive particle size)varied in steps to evaluate the friction and three body abrasive wear response of the composites.The design of experiment using Taguchi’s orthogonal array and analysis of variance(ANOVA)was applied to find out minimum specific wear rate.The results revealed the significance in arrangement of two different layers of fabric(glass and carbon)and the difference in properties obtained by them.Using Taguchi experimental analysis it has been observed that three body abrasive wear rate is minimum at 72 cm/s sliding velocity,30 wt.%fabric content,80 N normal load,90 m sliding distance and 125μm abrasive particle size.The scanning electron microscope(SEM)studies revealed the dynamics of three‐body abrasive wear and underlying micro‐mechanisms that result in the analysis of three body abrasive wear.

The Hydraulic Control Using LabVIEW for a Synthetic Rubber Spring Testing Machine

The application is a control movement of two hydraulic cylinder for a synchronize movement. The main purpose of this paper is to show a short programming code in LabVIEW to control the movement of two cylinders with an automatic control program using only analog inputs from the sensor of pressure and linear displacement sensor and the digital output from the hydraulic valves. This is designed for one of the test of this synthetic rubber spring testing machine.

Effect of hygrothermal aging on moisture diffusion and tensile behavior of CFRP composite laminates

Carbon Fiber Reinforced Polymer(CFRP)composites are widely used in aircraft structures,because of their superior mechanical and lightweight properties.CFRP composites are often exposed to hygrothermal environments in service.Temperature and moisture can affect the material properties of composites.In order to make clear the moisture diffusion behavior and the properties degradation of composites,the TG800/E207 composite laminates with four stacking sequences[0]16,[90]16,[±45]4s,and[(+45/0/0/-45)s]sare designed and manufactured.Moisture absorption tests are carried out at 80℃,90%RH.It is shown that the moisture absorption curves of composite laminates present a three-stage.A modified Fickian model was proposed to capture the diffusion behavior of TG800/E207 composite laminates.The relationships among the non-Fickian parameters,the environmental parameters and the stacking sequences of CFRP were correlated and compared.Results showed that the modified Fickian curve is sensitive to the diffusivity of Stage Ⅰ and Stage Ⅱ.Compared with unaged specimens,the maximum tensile stress for[0]16,[90]16,[±45]4s,and[(+45/0/0/-45)s]sdecreased by 14.94%,28.15%,11.96%,and 26.36%,respectively.The strains at failure for[0]16,[90]16,[±45]4s,and[(+45/0/0/-45)s]sdecreased by 55.38%,62.65%,46.41%,and31.71%,respectively.The elastic modulus for[0]16,[90]16,[±45]4s,and[(+45/0/0/-45)s]sincreased by 90.93%,94.57%,49.22%,and 8.22%,respectively.[90]16sample has the minimum saturated moisture content and the maximum strength degeneration.

Low velocity impact response and energy absorption behavior on glass fibre reinforced epoxy composites

A study was undertaken to determine the effects of several key geometry influencing factors on the impact response and energy absorption behavior of the glass fibre reinforced epoxy composites at low and intermediate energies.The energy-balance model was employed for characterising the energy absorption behavior and it depends strongly on the plate diameter and thickness.In addition,the damage vs.energy and force maps is effective in monitoring damage growth within the composite panel.The response of the composite laminate configurations characterized by different stacking sequences subjected to low velocity impacts with different impact energies have also been studied to estimate the damage initiation of composites.

Low-Velocity Impact and Compression-After-Impact Behaviour of Flax Fibre-Reinforced Composites

This study details the low-velocity impact and compression-after-impact(CAI)behaviour of flax fibre-reinforced polymer(FFRP)composites.The impact resistance,energy absorption efficiency and residual compressive strength as well as the damage pattern of the FFRP composites are compared with the corresponding features of glass fibre-reinforced polymer(GFRP)composites,and the effect of the stacking sequence of FFRP composites is also investigated.The results show that the cross-ply FFRP composites have the highest impact resistance,whereas the multi-directional ply composites have the lowest impact resistance but the highest energy absorption efficiency.The energy absorption efficiency of the FFRP composites is greater than that of the GFRP composites,but the penetration resistance and residual compressive strength of the FFRP composites are lower than those of the GFRP composites with the same stacking sequence,mainly due to the lower tensile strength and elongation at fracture of the FFRP composites.It is also reported that the damage pattern of the FFRP composites is localised cracking and delamination,unlike the overall delamination failure exhibited in the GFRP composites after CAI testing.Finally,the failure mechanisms of the FFRP and GFRP composites are detailed.