Advanced Materials Research Vol. 633

Abstract: This paper presents a comprehensive biomimetic design approach to developing novel load bearing lightweight vehicle structures inspired by the structural properties of animal bones. Lightweight vehicle structures developed in this way would have increased stiffness at significantly reduced weight. In this research, trabecular (cancellous) bone was analyzed at the metaphyses of four different species including rat, rabbit, chicken, and sheep. Three-dimensional models of bone structures were reconstructed from micro-CT scanned images using the computer aided design software Mimics. Force resistance and energy absorption properties of relevant bone structures subjected to quasi-static compression loads were investigated and analysed using the Finite Element (FE) method. Based on the obtained results, the paper discusses the effects of load directions, bone structure allocation and model thickness on the energy absorption and force resistance of the bone structures. The simulation results obtained in this research were compared to the results of conventional vehicle side intrusion bars.

Abstract: The paper presents a novel approach to comparative evaluation of engineering design concepts that exhibit non-linear structural behaviour under load. The developed method has extended the substructures technique in order to apply the Finite Element Analysis (FEA) method to complex non-linear structural problems in the conceptual design phase. As conventional FE models based on substructures allow only linear analysis, it was necessary in this research to introduce a new algorithm capable of linearizing non-linear structural problems with sufficient accuracy in order to enable comparative evaluation of design concepts relative to each other under the given constraints and loading conditions. A comparative study with respect to model size, efficiency, accuracy and confidence was performed to validate the developed method. Obtained results indicate significant improvement over more traditional approaches to applying FEA in the conceptual design phase. The improvements achieved using the developed method compared to the traditional FE based approach are superior by a factor of 2.7 in efficiency and by a factor of 4.5 in confidence while not sacrificing the optimality of the solutions.

Abstract: New exotic materials such as titanium alloys and carbon fiber reinforced plastics require strong hard cutters made of cubic boron nitride or polycrystalline diamond. However, the traditional mechanical diamond grinding process is slow and causes damage to the workpiece. This chapter examines the design requirements of an electrical discharge machining system that can be used to machine polycrystalline diamond tipped carbide drills. A preliminary theoretical model is described but the system complexity requires a gain scheduling approach to the control system design.

Abstract: Natural, synthetic and combinations of natural and synthetic materials are used widely in contemporary sports surfaces which have been designed to encourage elastic deformation under load, in order to increase athletic performance and at the same time reduce the risk of injury. In response to this need, manufacturers have developed a wide variety of indoor sports flooring systems types, which are generally separated into two major categories, area-elastic sports surfaces and point-elastic sports surfaces. Area elastic sport surface structures attenuate energy by allowing deformation over a comparatively large area, where as point elastic sport surface structures deform in response to applied forces over a relatively small area, in close proximity to the point of impact. Sports surfaces can therefore be extremely complicated arrangements of materials, which contribute to a surfaces complex behaviour. The materials used in each of these surface categories, attenuate the energy applied to a surface by an athlete, in order to reduce the energy returned to the athlete. Viscoelastic materials are therefore used as synthetic shock absorbers, in order to reduce the amplitude and increase the duration of an applied shock. To understand the cushioning properties of these materials, it is necessary to consider the structural aspects of the various material combinations. It is the aim of this chapter to discuss the types of sports surface materials used, the ways in which the materials are configured and the performance standards which have been applied, in order to evaluate athletic performance and reduce the risk of injury to an athlete.

Abstract: This article presents research motivated by the prospect of imminent implementation of the new regulatory requirement for pedestrian protection GTR9 (Global Technical Regulation9). A new methodology has been developed for optimisation of the hood panel of passenger cars to ensure that the pedestrian Head Injury Criterion (HIC) falls below the threshold values specified by both the GTR9 and the consumer metric, the Australian New Car Assessment Program (ANCAP). To meet the performance criteria for pedestrian protection head impact, it is vital to incorporate the associated design parameters into the hood design process at an early stage. These parameters are architectural in nature whereby changing them later in the vehicle design process would be very expensive and difficult to implement. The developed methodology for the design of a hood configuration aims to provide a robust and homogeneous HIC for different impact positions in the central area of the hood of a large sedan, taking into consideration the limited space available for deformation. The non-linear Finite Element Analysis (FEA) software LS-DYNA was used in this research to simulate the GTR-9/ANCAP pedestrian head impact testing procedures. The efficiency of a hood design was calculated as the ratio of the theoretical optimal deformation of hood assembly for a given value of HIC to the actual deformation calculated for the same HIC value of the corresponding numerical test. The efficiency and HIC value were derived for each configuration and compared to obtain the optimal solution for homogeneous performance and minimal deformation of outer and inner hood panels. The Kriging response surface and the Monte Carlo method were used in the design of numerical experiments. The outcomes of this study provide a clear indication that an optimum configuration of the hood panel of a passenger car can be developed to minimize the hood deformation while meeting the requirement for HIC value.

Abstract: This paper presents a comprehensive analysis of the assembly processes for single-row ball bearings. There are two different types of assembly processes, which depend on ball numbers and ball bearing ring designs. In the case of deep groove ball bearings, assembly is usually undertaken through slight deformation of the outer ring to increase clearance for insertion of the final ball. As a result, the outer ring takes an elliptical instead of a circular shape and requires deformation to be below a critical level to avoid fracture. Causal analysis of outer ring fracture during assembly is the main goal of the presented analysis, based on the expressions of the Theory of Elasticity for the thin ring exposed to bending, as well as Finite Element Analysis (FEA). The theoretical and numerical results have been verified by experimental testing.

Abstract: The gear tooth profile has an immense effect on the main operating parameters of gear pairs (load capacity, working life, efficiency, vibrations, etc). In current engineering research and practice, there is a strong need to develop methods for tooth profile optimization. In this paper a new method for selecting the optimal tooth profile parameters of spur gears is described. This method has been named the Explicit Parametric Method (EPM). The addendum modification coefficient, radius of root curvature, and pressure angle of the basic rack for cylindrical gears, have been identified as the main tooth profile parameters of spur gears. Therefore, the EPM selects the optimal values for these three tooth profile parameters. Special attention has been paid to develop a method of adjustment for the particular working conditions and explicit optimization requirements. The EPM for optimal tooth profile parameters of gears uses contact nonlinear Finite Element Analysis (FEA) for calculation of deformations and stresses of gear pairs, in addition to explicit comparative diagrams for optimal tooth profile parameter selection.

Abstract: One of the most important characteristics of a rolling bearing is the load distribution on rolling elements. This paper provides an analysis on the influence of the internal construction of rolling bearings on load distribution and the number of active rolling elements. The analysis was performed using a new mathematical model for the boundary level calculations of the bearing deflection and external radial load for the inner ring support on q rolling bearing elements. The model considers two boundary positions of inner ring support on an even and odd number of rolling elements. The developed model enables a very simple determination of the number of active rolling elements participating in an external load transfer, depending on the bearing type and internal radial clearance.

Abstract: A special kind of the basic involute profile of non-standard gearing is called high contact ratio (HCR) gearing, where the contact ratio is higher, there are always at least two pairs of teeth in contact and the unit addendum height is not equal to one like for standard gearing. Thus, the tooth height is increased. When HCR gearing is used, it is not necessary to achieve a greater gear load capacity, but nevertheless there is a greater risk of interference due to the greater tooth height. The advantages of HCR gearing is higher resistance (load is distributed on more pairs of teeth at the same time) and a lower relative noise level of gearing, which can be significantly reduced by using an integer HCR factor. HCR profiles are more complicated than standard involute profiles, they have a greater predisposition for interference, pointed tip thickness and undercut of teeth during production (primary production interference). Due to increased addendum height, there is a larger possibility of some interference or pointed tooth tip occurring. Therefore, these issues need to be prevented in the design phase, and ensured that all relevant equations and constraints are satisfied. The described method of finding optimal gear parameter values uses a Generalized Particle Swarm (GPS) optimization algorithm and MATLAB. The GPS optimization is shown to be a very fast and reliable method.