Advanced Materials Research Vol. 445

Abstract: Computer aided process planning is the bridge between CAD and CAM. Setup planning is the major key to transform design concept into manufacturing domain, which is mainly experience based activity in modern manufacturing industry. Setup planning is a complicated non-linear task constrained by many factors such as tool approach direction, geometric feature relationship, fixturing constraint, tolerance requirement and manufacturing practice. Setup planning identifies which features must be machined in each setup and determines locating datum for each setup. This paper focuses on the development of a formalized procedure for automatic generation of feasible setups. For preventing of tolerance stack-up tried to use datum face as reference plane in fixture design. So, this paper presents a new method for setup planning with accurate respect to datum faces in design and machining. For the proposed work the authors have introduced two concepts namely, inferiority face and control face. A rule-based procedure in several steps is used for solving the problem. The system is developed in Visual Basic on a Solid Works platform. Trial runs with industrial parts indicate that the system is applicable for industrial use.

Abstract: Low velocity drop weight impact testing of CPVC pipes was conducted on 160 mm long pipe sections obtained from 4-inch (100 mm) diameter schedule 80 pipes. Impact test were carried out for the base (as received) pipes and after their exposure to out door natural weathering conditions in Dhahran, Saudi Arabia. The results of the impact testing on the natural (outdoor exposure) broadly suggest that the natural outdoor exposures produce no change in the impact resistance of CPVC pipe material for the impact events carrying low incident energies of 10 and 20J. At the impact energies of 35 and 50J the natural outdoor exposures appear to cause appreciable degradation in the impact resistance of the CPVC pipe material. This degradation is noted only for the longer exposure periods of 12 and 18 months.

Abstract: This paper describes how deep cryogenic treatment at 98K produces changes in the microstructure of a heat-treated aluminum alloy. It was observed how the sub-micrometric particles increased near and at the grain boundaries. This slight precipitation did not produce any modification in static mechanical properties. However, the compressive residual stresses of the material were higher after compared to before the treatment. Both these effects can enhance the life of this alloy through cryogenic treatment.

Abstract: This paper describes a virtual prototyping (VP) system which is a part of an open source software package for an additive manufacturing (AM) process under development. The VP system facilitates the product development by uniting the AM process and virtual reality in order to produce digital prototypes. Moreover, it combines particle based and layer based processes by including powder-like particles as its basic material. These particles are used as color codes in the VP system. This coding enables obtaining basic building blocks in homogeneous state or in heterogeneous state by mixing with other particles. These blocks or bricks are collated side by side to obtain the heterogeneous material property all over the solid body. The thin layers obtained by these bricks are then subsequently stacked up to fabricate a virtual prototype. Construction of multiple material prototypes is possible due to selective-additive nature of this process. The effectiveness of the proposed system is demonstrated by processing a model of The Maidens Tower.

Abstract: The present paper presents an analysis of the influence of loading history on unstable fracture of austenitic steel 304 (SS 304) using the J-integral and its applicability in situations where a loading history exists. A CT specimen is employed for the purpose. The loading history effect on the unstable fracture of SS 304 is studied by performing cyclic loading with different load histories at constant load range (ΔP_i) and at constant stress intensity factor range (ΔK_j). The results show that the plastic singularity is well described by the integral (J) for the different types of loadings used. Moreover, the real meaning of (J_IC) as a representative of the maximum energy release rate is quite limited if it ignores the loading history. The experimental results show that the dissipated energy ΔJ is more active when the loading is done at constant ΔP. The evolution of ΔJ can be directly linked to the crack growth rate and to the extent of the plastic zone developed at the crack tip.

Abstract: The use of bovine hydroxyapatite (BHA) provides an alternative approach in bioceramics based on natural resources, time and cost efficiency. In this study, composites of calcinated bovine derived BHA were utilized. These were doped with known quantities of boron based bioglass (5 and 10 wt. %) and a range of composites were prepared at selected sintering temperatures (1000-1300 °C). The resulting structures were tested for several mechanical properties (porosity, compression and microhardness). Micro-structural analysis (electron microscopy and x-ray diffraction) was also performed on these samples, and these findings were correlated with results obtained from mechanical tests. The results indicate that there is a positive correlation between compression strength and sintering temperature and the optimal properties are obtained at a temperature of 1200°C and a boron oxide bioglass doping content of 5 wt. %.

Abstract: This paper presents the results of experimental studies carried out to conduct a comprehensive investigation on the influence of tool material on the characteristics of Electrical Discharge Machining process of AISI H13 tool steel. The studied process characteristics included the tool wear ration and thickness of the white layer on the workpiece after the EDM process. The experiments carried out under the designed full factorial procedure and the considered EDM input parameters included pulse on-time and pulse current. The results of this study could be utilized to choice a set of pulse on-time and pulse current according to the outcomes that suit the requirements of tool-workpiece combination processed by the EDM.

Abstract: This paper details the correlation between the input parameters with the tool material on the machining response in comparison of two different combinations of toolworkpiece material, namely copper-H13 and graphite-H13. The considered machining input parameters included pulse current and pulse on-time, and the investigated characteristics of the machining response were the material removal rate, tool wear, and surface roughness of the workpiece. Furthermore, differences in pulse shapes and process stability between the copper-H13 and graphite-H13 combinations were investigated.

Abstract: Hybrid adhesive joint is an alternative stress reduction technique for the adhesively bonded joints. Hybrid adhesive means that it is used dual adhesives in the overlap region. Adhesive having high modulus of elasticity should be located in the middle of the bondline and the other adhesive having low modulus of elasticity at the ends. In this study, the effect of the hybrid adhesive bondline on the distributions of the peeling, shear and von Mises stress components at the single lap joint were investigated by using three-dimensional finite element model. The results show that the considered stress components can be optimized by using hybrid adhesive joint.

Abstract: Optimisation of geometric parameters of gears under variable loading condition is studied. Bending stress is considered as objective function and contact stress is considered as constraint function. Bending stress and contact stress are calculated depending on zero tooth modification, positive tooth modification and negative tooth modification by using developed MATLAB program respectively. Obtained results are compared and presented graphically. It is concluded that tooth modification is effective parameter for optimisation of geometric parameters of gears under variable loading condition. By optimising the geometric parameters of the gears, such as, the module, number of teeth, helix angle, and face width, it is possible to obtain a light-weight-gears structures. All optimised geometric design parameters also satisfy all constraints.