Applied Numerical Analysis. By C.F. Gerald. Pp. xii, 340. £3·60. 1970. (Addison-Wesley.)

Weight reduction of vehicle is very important because vehicle weight directly affects energy consumption. Studies researching lightweight vehicle manufacturing process that use polymers are reviewed in this paper. Approaches reducing the weights of vehicles using polymers most frequently involve replacing ferrous and non-ferrous metals with polymers and increasing the specific strengths and rigidities of polymers. Researches into polymers for use in lightweight vehicle are classified into high performance polymers, polymers for weight reduction, reinforced polymer composites, polymer sandwich panels, and polymer/metal hybrid systems. A diverse range of polymer materials can be used to make vehicle components and the manufacturing methods required to produce and work those materials vary greatly. Shaping processes must be chosen according to the materials being used and the product design. Replacement of metal products with polymer materials in current vehicles is limited. Large amounts of lightweight materials, such as polymers, will be greatly used to construct newly developed vehicles, including electric and electric/hybrid vehicles.

Research trends in polymer materials for use in lightweight vehicles

Design optimization and manufacture of hybrid glass/carbon fiber reinforced composite bumper beam for automobile vehicle

The near-dry wire-cut electrical discharge machining (WEDM) process is an environment-friendly manufacturing process, in which there is no harmful effect to the operators. The authors focus on the non-polluting ways to cut the materials and to meet the technical requirements like high material removal rate (MRR) and low surface roughness (Ra). In the near-dry WEDM, the finite discrete periodic series sparks between the wire electrode and conducting work material separated by minimum quantity of deionized water mixed with compressed air (air-mist) as a dielectric medium. In the present research, parametric analysis of the process has been performed with the molybdenum wire tool and high speed steel (HSS-M2) work piece. Experiments have been performed using air-mist as the dielectric medium to study the impact of gap voltage, pulse-on time, pulse-off time, air-mist pressure and discharge current on the MRR and Ra using the mixed orthogonal (L18) array-Taguchi method. Taguchi based analysis of variance test was performed to identify the significant parameters. The gap voltage, pulse-on time, discharge current and air-mist pressure were found to have momentous effects on MRR and Ra. The best regression models for MRR and Ra have been developed by regression analysis. The optimal rough and finish cutting parameters have been predicted by Pareto-front using the multi-objective evolutionary algorithm (MOEA).

Experimental investigation and parameter optimization of near-dry wire-cut electrical discharge machining using multi-objective evolutionary algorithm

Mechanical properties and global stability of foam core sandwich structures are highly controlled by the shear response of the core material. In this work, we have studied the shear deformations of three common structural core materials with the aid of full-field optical analysis. The chosen core materials are namely extruded PET foam ( ρ  = 105 kg/m 3 , G xz  = 21 MPa,) and cross-linked PVC foam ( ρ  = 60 kg/m 3 , G xz  = 22 MPa) which have comparable shear properties, as well as Balsa wood with the lowest density commercially available ( ρ  = 94 kg/m 3 , G xz  = 106 MPa) as a reference core material. Both global and local shear strains in the core materials are calculated and graphically visualized. In the elastic region, foam cores showed more uniform deformations than Balsa. Yielding and shear failure of the two foam core materials were quite different. The PVC foam experienced a high local deformation under the load introduction bars, from which sub-interface shear failure initiated. The PET foam, in contrast, showed no sign of stress concentrations, resulting in a homogenous evolution of shear deformations in the mid-core regions. A comparison between the direct foam shear test and sandwich specimen bending suggested that the former method might not be capable of capturing a full picture of the in-service core shear response.

Full-field shear analyses of sandwich core materials using Digital Image Correlation (DIC)

The purpose of this study was to design a light-weight sandwich panel for trailers. Strength calculations and selection of different materials were carried out in order to find a new solution for this specific application. The sandwich materials were fabricated using vacuum infusion technology. The different types of sandwich composite panels were tested in 4-point bending conditions according to ASTM C393/C393M. Virtual testing was performed by use of ANSYS software to simplify the core material selection process and to design the layers. 2D Finite element analysis (FEA) of 4-point bending was made with ANSYS APDL (Classic) software. Data for the FEA was obtained from the tensile tests of glass fiber plastic (GFRP) laminates. Virtual 2D results were compared with real 4-point bending tests. 3D FEA was applied to virtually test the selected sandwich structure in real working conditions. Based on FEA results the Pareto optimality concept has been applied and optimal solutions determined.

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Design and Testing of Sandwich Structures with Different Core Materials

The paper addresses the issue of embedding the rectangular printed circuit board (PCB) - the placeholder for a complex sensor system circuit - in the glass fibre laminate during the lamination. The change of the material mechanical properties due to the presence of foreign objects in the laminate is assessed by experimental testing through standardized methods ASTM D3039, ASTM D6641 and ASTM D3518. Local stress-strain relationship near the PCB in the out-of-plane direction of the specimen are monitored through the use of GOM ARAMIS 2M digital image correlation method scanner. Based on the scanned model, a finite element simulation is generated and validated.

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Visualization of strain distribution around the edges of a rectangular foreign object inside the woven carbon fibre specimen

A complex electronics circuit placeholder is embedded in the carbon fiber laminate. The reduction of the material mechanical strength is assessed. The strain interaction between electronics and carbon fiber laminate is measured with digital image correlation based deformation scanner GOM ARAMIS 2M. A finite element analysis model is developed and validated. Based on FEA results the response model for prediction of the mechanical properties of laminate is introduced.

Georg Allikas

Papers

Design and Testing of Sandwich Structures with Different Core Materials

Visualization of strain distribution around the edges of a rectangular foreign object inside the woven carbon fibre specimen

Embedded Electronics Influence on the Strength of Carbon Fiber Laminate