This paper deals with modeling of the interaction in overlapping cracks that the authors have earlier identified to be generic to a wide range of polymeric systems (Ramasamy and Lesser, J Polym Sci B Phys, 2003). A complex stress function method is used for evaluating stress intensity factors for interacting cracks. The interaction between two parallel overlapping cracks is considered first. It is shown for this case that the stress intensity factor can fall below the threshold value when there is sufficient overlap, leading to arrest of crack growth at the overlapping tip. Then the interaction in a doubly periodic infinite array of cracks is considered. The interaction in the array is found to be non-linear. However, at a given stress level, the highest density of stable cracks is related to the threshold value for crack propagation K th though a simple set of equations. It is also shown that in an infinite array of cracks, the energy release rate criterion for crack growth is different from the stress intensity factor criterion due to a reduced stiffness of the material.

A production unit could be claimed successful, only when it increases the likelihood of easy assembling and minimizes unit production cost. In order to undergo mass production methods, their orientation play a major role in enabling the ultimate operational time and cost. To cope up with such methods, the use of jigs and fixtures are facilitated. The paper encompasses the alternative solution for material handling flaws caused in the assembly process. The frequent reasons for the leakage are the improper positioning of the ceramic bushes in the impeller casing unit, owing to the downfall of the motor efficiency. The bushes are placed manually in general, leading to the improper positioning of the bushes, getting in contact with the rotor/impeller resulting in non-uniform wear, leading to water leakage. These defects could be overcome by introducing an assembly fixture for motor placement and using pneumatic cylinder actuation for the accurate bush placement. This indeed includes the reduction of idle lead time in the assembling process by automating the process of manual bush placement and the manufacturing of defect free products. This signifies the reduced lead time to increase the productivity factor and the efficiency of the motors. Lean study was conducted to reduce the lead time and Value Stream Map (VSM) is reported in this paper.