International Journal of Mechanical Engineering

8

Authors: HANNA FARON, WOJCIECH MARCINKOWSKI, WŁADYSŁAW HAMIGA & DANIEL PRUSAK

At high speed, which is developed during the races, the ability to control the movement of the vehicle determines the winner. In order to obtain improvement, by use of the series of activities aimed at interference with the air flow, there was a tendency to provide increased downforce. As for the verification of the drivability and to simulate the behavior of the car on the track, during design phase the analysis was carried out by use of characteristics such as cornering stiffness, steer angle, understeer gradient, yaw and characteristic velocity.

10

Authors: M. T. ZARMAI, N. N. EKERE, C. F. ODUOZA & E. H. AMALU

The solder joints in crystalline silicon solar cell assembly undergo thermo-mechanical degradation during the device lifetime. The degradation is accelerated by the formation and growth of intermetallic compound, IMC, in a solder joint which contains copper and tin as alloying elements of the solder. This investigation quantifies the contribution of the presence of IMC in the joints on the reliability of the assembly. The study employs finite element modelling (FEM) to simulate the nonlinear deformation of SnAgCu solder joints in two models of crystalline silicon solar cell assembly. One of the models contains IMC in the interface joints between solder and copper ribbon while the other, which is the control, does not contain IMC in the joints. The degradation of the solder material is simulated using Garofalo-Arrhenius creep model. The geometric models were subjected to accelerated thermal cycling utilising IEC 61215 standard for photovoltaic panels. Analysis of the results of the creep strain profiles of the two models indicate that the deformation amplitude in the solder joint containing IMC is higher than that in the solder joint containing solder only. Similarly, it can be observed from the plot of strain energy density against load step that the solder joint containing solder+IMC have considerable higher strain energy density compared to solder only joint. This infers that the presence of IMC significantly impacts the thermo-mechanical reliability of the assembly joints. The results also demonstrate that IMC decreases the mean-time-to failure (MTTF) of the assembly joints.

10

Authors: CH. SIVA RAMA KRISHNA, K. S. RAGHURAM & D. AJAYKUMAR

The aim of this investigation is to check t the process parameters that affect Ni-Cr electroplating on Mild steel. To evaluate the process three of process factors were selected: the amount of voltage, the time that the voltage is applied, temperature of the process are the factors that were tested. The hypothesis for each factor was developed as: The relation between the time and the thickness of metal coated should be proportional up to 4.1 volts and later on decreases. For a certain time interval, when the thickness of Ni-Cr plating developed on the Mild steel is constant after 19 seconds of time. The thickness of metal deposited also depends almost linearly with respect to process temperature. After a series of experiment following were concluded: Time is proportional to surface thickness and surface thickness also increases with temperature.