DESIGN AND ANALYSIS OF INTEGRALLY- HEATED TOOLING FOR POLYMER COMPOSITES

Almost all of chapters 4, 5 and 6 of the entire PhD thesis are published as: 1) Conference paper (Numerical Studies of Integrally-Heated Composite Tooling). Presented in ECCM16, 22-26 June 2014 Seville, Spain. 2) Journal paper (Numerical simulation and design optimization of an integrally-heated tool for composite manufacturing). Submitted 29 April 2014 to journal of Materials and Design for publication, Accepted 10 July 2014 and Available online 1 August 2014. 3) Journal paper (Numerical Simulation and Experimental Verification of Heating Performance of an Integrally Water-heated Tool). Submitted 16 September 2015 to journal of Reinforced Plastics & Composites, Accepted 23 November 2015 and Available online 28 January 2016. 4) Manuscript (Numerical Analysis of the Thermomechanical Behaviour of an Integrally Water-Heated Tool for Composite Manufacturing). Submitted for publication on 31-March-2016 in journal of Composite Structures. Manuscript ID: COST-D-16-00629.Tooling design is crucial for the production of cost-effective and durable composite products. As part of the current search for cost reduction (by reducing capital investment, energy use and cycle time), integrally-heated tooling is one of the technologies available for ‘out-of-autoclave’ processing of advanced thermoset polymer composites. Despite their advantages, integrally-heated tools can suffer from uneven distribution of temperature, variability in heat flow rate and inconsistency in heating/cooling time. This research, therefore, investigates a number of design variables such as shape and layout of heating channels in order to improve the heating performance of an integrally-heated tool. Design of Experiments (DoE) has been carried out using Taguchi’s Orthogonal Array (OA) method to set several combinations of design parameters. Each of these design combinations has been evaluated through numerical simulation to investigate heating time and mould surface temperature variation. The simulation results suggest that the layout of the channels and their separation play a vital role in the heating performance. Signal-to-Noise (S/N) ratio and analysis of variance (ANOVA) have been applied to the results obtained to identify the optimal design combination of the integrally-heated tool. Statistical analysis reveals that the heating performance of an integrally-heated tool can be significantly improved when the channels’ layout is parallel. The shape of the channels has negligible effect and the distance between the channels should be determined based on the production requirement. According to the predicted optimal design, a developed integrally water-heated tool is manufactured. The actual thermal properties of the constituent materials of the produced tool are also measured. Then a numerical model of the experimental tool model is simulated in ANSYS software, with setting the actual material properties and boundary condition to define the temperature uniformity and heating rate of the experimental tool. Comparison of the experimental and numerical results of the experimental tool confirmed the well assigning of the boundary conditions and material properties during simulation the heated tool. The experimental results also confirmed the predicted optimal design of the integrally heated tool. Finally, in order to define its thermomechanical behaviour under the effective (in service) thermal loads, a tool model is simulated. Numerical results presented that the produced extremes of thermal deformation, elastic strain, normal and plane shear stresses, under the effective thermal loading, are within the allowable elastic limits of the participated materials.Ministry of Higher Education and Scientific Research of Ira

Flexural Behavior of CFRP Laminate at Elevated Temperature

A carbon fibre reinforced polymer (CFRP) laminate forms the surface part of an integrally heated tool. It was made up of carbon non-crimp triaxial fibre and SR8100 epoxy in accordance to the stacking sequence of [(0, ±45)/ (90, ±45)] S, using the resin infusion (RI) method. The laminate is heated up to 90ºC when the tool is operated; therefore under-standing the effect of temperature on the flexural properties is quite significant. This experimental study is carried out to investigate the flexural behaviour of the CFRP laminate and finding its flexural properties under the effect of elevated temperatures. For this purpose, various CFRP specim-ens were prepared and tested, using three point bending test method, at different temperature levels from room temperature to 90ºC. The results show that each of the flexural peak load, modulus and strength of the laminate decreases consistently with the increase of temperature. Also the laminate becomes slightly more flexible and significant loss occurs in its flexural modulus when the temperature elevates from 75ºC to 90ºC. The reduction in the flexural behaviour of CFRP is imputed to thermal softening of the epoxy polymer matrix whenever becomes closer to (HDT)

Impact of textile types and their hybrids on the mechanical properties and thermal insulation of mohair-reinforced polyester Composite laminates

Mohair fibres from animals are a great choice for people who care about the environment. They have low toxicity, are abundant in raw materials and don't pose any health risks. However, when compared to synthetic fibres, their mechanical performance is not as good. Mohair fibres are best suited for low to medium load applications, such as car parts, agricultural equipment, sports equipment and household items. Despite their excellent properties, there is still a lot we don't know about mohair textile-reinforced polyester composites. The novelty of this study is testing different mohair fibre textiles to see which one provides the best characteristics. The three most commonly used locally-made mohair fabrics (woven, knitted and pressed mat) were selected as reinforcement in polyester resin. Nine different laminates of similar and hybrid layers were made by hand lay-up in a closed mold at a constant fibre weight fraction (number of layers), mold pressure, curing time and temperature. The results showed that the composite laminate of mat fabric reinforced polyester provides the maximum tensile strength, elongation, flexural strength and thermal insulation of 22 MPa, 2.2 %, 54.6 MPa, 0.27 J and 0.012 m2°C/W, respectively. Meanwhile, the woven laminate exhibited the highest impact strength of 0.27 J and the hybrid laminates of the mat and woven fabrics offer satisfactory strength of 0.25 J