UTAR Engineering Student

Position Control with Speed Feedback When the gain is raised in a position control system to minimize the deadband effect, the closed loop system responded with an overshoot which resulted in undesired system oscillation. One way to mitigate oscillation is to add a brake which is proportional to the speed to the output shaft. The brake method may produce a satisfactory result. However, it consumes a significant power and makes acceleration of the load difficult. Better way of preventing oscillation is to add a speed control loop to the position control loop. The speed control loop provides a negative feedback signal from the output of the Tachogenerator which is proportional to the speed of the motor. The effect of adding a speed loop is illustrated in Figure 1 (a), (b), and (c). An optimum control of the speed feedback loop produces a system response as shown in (b). Figure 1 : Effect of a speed feedback loop...

Metal Fatigue Metallic fatigue occurred at both low and high temperature. It is considered mainly from the perspective of the interaction between the microstructure, the deformation mode, and the mechanical state (Pineau, et al., 2016). The fatigue strength of metals is depending on the crack growth resistance provided by the grain boundaries, the phase boundaries, and various dislocations present in the material (Vallellano, et al., 2009). Therefore, fatigue crack initiation position and the minimum load cycle number before initiation of fatigue are essential to determine in the fatigue analysis. (Topaç, et al., 2009). Fatigue is a type of failure that takes place in the structures when exposed to dynamic forces. Those dynamic forces will produce dynamic stresses and give rise to fatigue failure of structures. The real-life example is fatigue failure of vehicle’s axle housing arisen due to dynamic stresses that induce by rough and uneven road surface (Topaç, et al., 2009). Ne...

Material Selection for Heat Insulation The selection of insulating material is depend on the properties of material such as thermal resistance, heat capacity, density and thermal conductivity. The purpose of insulation is to ensure is to avoid the heat from radiating away and also to improve the working environment condition. Generally, insulation idea is approach by the heat capacity of material and the existing of pocket air , air has lower thermal conductivity than solid and the stagnant air has low convection air coefficient in the absence of bulk movement flow of fluid.  (1) Mineral Rock Form by spun molten glass, stone, ceramic fiber into fiber structure. (2) Calcium Silicate Form by react polyol (alcohol with two or more hydroxyl group) with polymeric isocyanate. (3) Fiber Glass Form by finely woven silicon, glass powder and tiny shards of glass spun into microfibers. (4) Polyurethane Foam Form by react methylene diphenyldiisocyanate (MDI) and...