No abstract

Pigment levels are known to have an effect on defect formation of the plastic injection moulding parts. Warpage, Shrinkage and Flash are common defects that were found during plastic injection moulding process. It was found that the pigment does play a role in the formation of defects on the plastic injection moulding parts. The main finding of this case study is to analyse and study the warpage, shrinkage and flash defects that were found in the Plastic Injection Moulding (PIM) parts which are moulded with different pigmentation percentages. It is also to identify the effects of the different pigments colours on the moulding quality of the parts when the pigment percentage is made constant. In this research, the dog bone design was used as the experimental specimen. The material used in this study is Polypropylene (PP). The other parameters such as injection pressure, melting temperature and cooling time were set to constant. The only parameter that varies is percentage of pigmentation. Warpage, Shrinkage and Flash defects are measured and calculated to obtain the value of defects. The pigmentation gives a huge effect on Warpage and Flash deformation. The warping and flash increase as the percentage of pigmentation increase. The highest value for warpage and flash are 3.0732 and 1.45304 respectively. Moreover, blue pigment gives the lowest value for Warpage and Flash defect. While yellow has the highest warping and flash defects. However, it was found that shrinkage is not affected by the pigmentation. The shrinkage result is less than 1%.

Bicycles continue to be a popular two wheeler mode of transportation even in the current era due to its nature in being environmental and entertainment friendly. This research in particular is conducted to study and analyze the structural stability of the cross country mountain bike frame with different rider loadings and materials. Three types of rider mass will be studied here, 60, 100 and 150 kg, each representing the common, medium and higher extreme weight range of user. The load will be distributed in several percentage break ups on the seat, paddle and handle as described in the study. The mountain bike frames structural performance is also evaluated with three different materials applied, namely titanium, aluminum and carbon fiber. The structure consisting of a standard diamond-shape crosscountry frame will be designed in a CAD modeling software, CATIA and pre-processed and post-processed in finite element simulation software, ANSYS. Analysis results from the numerical analysis are recorded in terms of stress plots, displacements and natural frequency values and mode shapes. Design optimization is performed on the regions indicating high stress plots to reduce the stress concentration and enhance the structural stability of the frame. Optimized design is validated again through numerical analysis.

No abstract

This study proposes a method of achieving an optimised vehicle front-end profile for improved protection for both adult and child pedestrian groups, which at the same time is able to avoid designs that may cause Run-over scenarios. A hybrid model of a seven-parameter vehicle front-end geometry and a pedestrian dummy is used. Latin Hypercube sampling is utilised to generate a Plan of Experiments for the adult and child pedestrian cases. Head injury criteria results from the simulations that are tabulated as the response functions. The radial basis function method is used to obtain mathematical models for the response functions. Optimised front-end geometries are obtained using the Genetic Algorithm method. The optimised vehicle front-end profile for the adult pedestrian is shown to be different from that of the optimised profile for the child pedestrian, and optimised profiles are shown to be not mutually applicable for safety. Furthermore, Run-over scenario is observed in child pedestrian optimised profiles, where its occurrence invalidates the optimisation. A simple weighting method is used to optimise the geometry for both adult and child pedestrian groups. The Run-over occurrences are mapped using Logistic Regression and is subsequently used as a constraint for optimisation. The final optimised model is shown to achieve a safe vehicle front-end profile which equally caters for both adult and child pedestrians while simultaneously avoiding Run-over scenarios.