In this work, the finite element analysis has been used to predict the
temperature distribution in Nd: YAG laser rod; double end-pumped by two
methods Gaussian or top hat beam. The rod is cooled by water passing through
annular, which surrounds the active media. The temperature distribution has
been used to predict numerically, the nodal displacements, strain and stress
based on the principle of virtual work. The main task is to determine the
temperature distribution in Nd: YAG laser rod, the subsequent value and
location of maximum tensile hoop stress associated with the two types of the
double end pumping for different absorption power. Some conclusions are
obtained; as the radius pumping ratio increases the location of maximum hoop
stress will move toward the periphery and vice-versa. Small reduction is
observed in the location of maximum hoop stress when pumping method change
from the top-hat beam to Gaussian beam, especially at low radius pumping
ratio and high absorption power. Top hat beam end pumping will cause more
intense tension hoop stress at the facets of the rod than that of Gaussian
beam even the later may produce high center temperature. This work may be
important for designer while choosing the type of pumping, maximum produced
tensile hoop stress and its location, especially when hoop stress is
ultimate.
Laser welding process reduces the heat input to the work-piece which is the main goal in aerospace and electronics industries. A finite element model for axi-symmetric transient heat conduction has been used to predict temperature distribution through a steel cylinder subjected to CW laser beam of rectangular beam profile. Many numerical improvements had been used to reduce time of calculation and size of the program so as to achieve the task with minimum time required. An experimental determined absorptivity has been used to determine heat induced when laser interact with material. The heat affected zone and welding zone have been estimated to determine the effect of welding on material. The ratio of depth to width of the welding zone can be changed by proper selection of beam power to meet the specific production requirement. The temperature history obtained numerically has been compared with experimental data indicating good agreement.
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