Energy Absorption and Strength Evaluation for Compressed Glass Fibre Reinforced Polyester (GRP) for Automobile Components Design in Crash Prevention Scheme

This paper utilized the compressive tests results to establish some critical mechanical properties and crashworthiness parameters that may be required to design GRP composites of polyester matrix in automobile structures. Third order polynomial function was used with numerical methods to establish the elastic properties whish could not be established due to sensitivity of the Monsanto tensometer used to obtain the compression results. This study showed that the finite difference method captured the general trend of experimental solution giving optimum value of compressive stress as 23.78MPa at strain of 0.018 and elastic limit of 12.01MPa at 0.01 strain through finite difference analysis while the solution with third order polynomial interpolation gave optimum compressive stress as 36.57MPa at 0.018 strain and elastic limit of 12.143MPa. Also established with compression data is the compressive or buckling moduli of 1.2GPa. Gauss-Legendre two point rule was used to evaluate the area under the stress-strain curve which measured the amount of energy absorbed per unit volume of sample from where the energy absorbed at ultimate strength of 0.025J/M3- 0.22 J/M3 , energy at fracture of 0.62 J/M3- 1.62 J/M3 and the absorbed specific work 0.001J/Kg are established.

The Influence of Creep on the Mechanical Properties of Calcium Carbonate Nanofiller Reinforced Polypropylene

The study focused on experimental and classical data to establish some mechanical properties for optimum design of new polypropylene components to serve under creep environment. The creep studies recorded stress limits that never exceeded 24.19MPa and maximum creep modulus that never exceeded 1.49GPa as against the predictions of classical equations that gave 2.0GPa for PPC0 and 2.46GPa for PPC2 at ambient conditions. The shear modulus and shear strength of the PPC0 and the PPC2 are predicted as 0.75GPa and 120MPa respectively and 0.92GPa and 150MPa respectively while the yield strengths found to be about 13.19MPa and 13.20MPa respectively for PPC0 and PPC2 at elastic strains 0.008 and 0.009 respectively. Further found are that as the material deforms the stiffness or modulus decrease, at low strains there is an elastic region, as temperature and applied stress increase the material becomes more flexible characterized with reduction in moduli. Plastic deformation at strains above 0.01 resulted to strain- hardening or strain-strengthening that manifested as the increasing area ratios and associated creep cold work. Also established by this study is a computational model for evaluating the elastic modulus of polypropylene matrix based material as expressed in equation (6). Both the Halphin-Tsai and the Birintrup equations for elastic modulus of unidirectional fibre composites were confirmed to be appropriate for prediction of elastic modulus of nanofiller composites with polymer matrix.

Creep Function Parameter Analysis for Optimum Design with Calcium Carbonate Nanofiller – Polypropylene Composite

This paper is about the use of power law model to fit experimental creep data of PP reinforced with calcium carbonate nanofiller at 10% optimum volume fraction with a view to characterizing the new material (PPC2) parametrically. The creep parameters were evaluated for neat (PPC0) and reinforced PP (PPC2) to establish the influence of reinforcement on the creep variables like creep rate and creep activation energy. The coefficient parameter A estimated within the stress level range 13.08MPa-22.88MPa has the range 0.0165-0.0651 while the exponent parameter n has 0.299-0.370. The creep stress coefficient K and exponent m has the respective values 161.495 and 0.3288 for PPC0 and 1881.4965 and 0.5448 for PPC2. The value of the parameter p similar to Larson-Miller has the value 4014.1871. Two creep function models used found that PPC0 has higher activation energy with value 9.3642E-20 J/mol for the stress 13.08MPa and PPC2 has values for the stresses 13.08MPa, 19.61MPa and 22.88MPa as 5.55998E- 20J/mol,5.4573E-20J/mol and 4.845E-20J/mol respectively. Of the two master curves produced, that following Larson-Miller parameter is recommended as the relationship between lnσ and parameter f(σ) is relatively linear and will give better results than the curve assumed to follow Sherby-Dorn that will give average result.

Thermal Cycling Effects on the Fatigue Behaviour of Low Carbon Steel

This paper examines the behavior of low carbon steels subjected to a frequency thermal cycling test. A compositional analysis was performed to ascertain the percentage of carbon in the asreceived materials. The specimens were machined to a precise gauge length and diameter and exposed to various cycles of heat at each temperature. A fatigue test was also performed with the use of Avery Dennison and bending stress was obtained using the curve supplied with the machine. The results from the machine were converted to Mega Pascal (MPa) and the values used to plot S-N curves and fatigue resistance for the specimens at various cycles and different temperatures were established.

The Effect of Bridging Liquid Surface Tension and Specific Surface Area on Strength Factor of Coal Agglomerates

The aim of this research is to determine the effect of bridging liquid surface tension and specific surface area on strength factor of coal agglomerates. The production of coal agglomerates of the range 15-27.51 mm was achieved. The crushing strength of the agglomerates was determined for good handling of fine （coal-liquid mixture） to improve fugitive dust control, decrease in transportation losses, reduce risk of coal freezing, lower risk of spontaneous combustion, etc. in iron and steel industries, railway corporations and coal corporations. Kerosene （paraffin oil） was used as a binder and the agglomerated coal oil mixture was pelletized using balling technique （disc）. Mechanical and physical tests like compressive strength test, etc. were carried out. The relationship between the bridging liquid surface tension and specific surface area on strength factor of coal agglomerates showed that there is considerable variation in these parameters in the coal powder systems.