The significance of machining parameter optimization is increasing day by day in the current manufacturing scenario. Many large industries have attempted to introduce the highly automated and computer-controlled machines as their strategy to adapt to the ever-changing competitive market requirement. Due to high capital and machining costs, there is an economic need to operate these machines as efficiently as possible in order to obtain the required pay back. This research looks to fill gaps in current residual stress modeling techniques. In particular, the research will focus on predicting residual stresses in milling and drilling process. Mild steel ASTM A36 is the material used here. An investigation on influence of machining parameters such as number of teeth of the cutter (Zc) and depth of cut (t) for milling, feed (S) and diameter of drill bit (d) for drilling. These parameters have large influence on the cutting force, and the response parameter is the residual stress. Experiments were conducted. Effects of input parameters on output responses were studied. The simulation is carried out with ANSYS workbench. And finally optimal parameter combination in milling and drilling is obtained.
The ultrasonic methods are widely used for evaluation of materials for its inexpensive and practical features. Among the largely used ultrasonic methods is the Critically Refracted Longitudinal Waves (Lcr), which applies longitudinal bulk waves travelling right below the surface, parallel to it. The method can be used to measure stresses near the surface through acoustoelasticity. However, the materials microstructure directly influences the propagation of these waves. The mean grain size is one of the factors that affect the wave speed. The purpose of this paper is to evaluate the effect of mean austenitic grain size in the time of flight (TOF) of Lcr wave. Samples (CDPs) of ASTM A36 steel were manufactured with dimensions of 5/8″ × 6″ × 12″. These were submitted to heat treating at the different temperatures ranges and cooled in air to generate different grain sizes. The results were compared to the grain size estimated in the literature and obtained from optical microscopy. The study showed a clear dependence of TOF on mean austenitic grain size for ASTM A36 steel. Such effect has to be studied to allow stress measurements with Lcr waves.
The kinetic energy of simulated rainfall is one of the parameters used to study the effect produced on the soil or a given crop. About this theme, we aim to determine the applicability of three commercial sprinkler heads for use in rainfall simulators by verifying the kinetic energy of the generated rainfall. Using an experimental workbench, the sprinkler heads were positioned at heights of 1.1, 2.1, and 3.1 m under pressures of 50, 100, and 150 kPa, which, when combined, generated 27 treatments with six repetitions. Using a disdrometer, the values for intensity (mm h-1) and kinetic energy (J.m-2.h-1) were collected. Three equations from the literature were employed to calculate the kinetic energy from the precipitation intensity provided by the disdrometer, allowing their comparison with the kinetic energy values measured by the disdrometer. The kinetic energy results measured by the disdrometer differed from the values calculated using the equations. The sprinkler heads P1, P2, and P3 did not generate rain droplets with kinetic energy similar to that of natural rainfall for the same intensity, thus not being qualified for use in rainfall simulators.
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