Papers by Author: Iyad T. Alzaharnah

Abstract: nternal heating of hollow cylinders with moving periodic heat source is examined in relation to surface treatment applications. This study includes three different cylinder materials, namely aluminum, nickel and titanium. Effective stresses in the cylinder wall are found to be mainly attributed to longitudinal temperature gradients. The aluminum cylinder shows sharper longitudinal temperature gradients as compared to the nickel and the titanium cylinders, which is due to the high value of the aluminum specific heat capacity. However, the larger Eα (elasticity modulus × thermal expansion coefficient) values for nickel cylinder result in higher levels of stress although nickel and titanium cylinders exhibit similar longitudinal temperature profiles. During dwelling time for the heating source at a certain spot, titanium cylinder exhibits lower levels of temperature increase as compared to aluminum and nickel cylinders, due to its lower value of thermal conductivity.

Abstract: Flexural motion of a cantilever bar can be used to monitor the taper angle measurements of the bar without incorporating any geometric measurement. This provides non-destructive taper measurement with fast processing in manufacturing line. The laser ablation of a free end of the cantilever bar enables to generate a recoil pressure at the irradiated surface while resulting in external forcing function for the initiation of the flexural motion. Consequently, in the present study, laser induced ablation of free end tapered cantilever bar and resulting displacement and frequency of the flexural motion is examined. The study is extended to include influence of positive and negative bar taper angles on the flexural characteristics. In addition, deviation of displacement and frequency of the flexural motion due to tapered bar from the parallel bar is examined. It is found that the flexural characteristics of the tapered bar enable to determine taper angle of the bar with high accuracy.

Abstract: The flexural motion of a bar changes during the welding process because of the temperature field, which modifies the modulus of elasticity. Depending on the duration of heating during the welding process, the wave characteristics of the flexural motion changes; therefore, the wave characteristics can be related with the heating durations. In the present study, welding of one end of a bar to a rigid body is simulated and flexural motion generated at the free end of the bar through impulse force is analyzed. Temperature field and flexural wave characteristics are computed for different heating durations. It is found that temperature decays sharply in the region next to the heat source, and this decay becomes gradual as the heating progresses. The effect of temperature decay on the characteristics of the flexural wave is significant in the early heating period and gradual decay of temperature in the bar modifies the wave characteristics considerably.