Computer aided structural analysis of power pack carrier structure in armored vehicles

In today's automotive industry, the increase in customer needs and the test costs required to meet these needs lead manufacturers to perform more effective engineering studies. Accordingly, military vehicle manufacturers attach great importance to design and design verification processes in order to increase personnel safety, improve on-vehicle system and subsystem component strength and reduce test costs which are much higher than passenger vehicles. In this thesis, the design and computer aided analysis of the power pack carrier structure carrying the engine, transmission and transfer case of a military vehicle, taking into account the operating conditions and mission profiles are explained. According to analysis results, a design improvement has been made on the power pack carrier structure, which is planned to be produced by welded or casting production method. In this thesis study, firstly, stuedies dealing with similar problems in literature research were examined; it has been determined that the parts on the vehicle are exposed to which loads, the determination of these loads and how their effects on the material are examined. Static analysis were carried out for the loads in crash and bump scenarios that a military vehicles encounter with high frequency within the scope of its mission profiles. According to the static analysis results of the welded carrier structure which is planned to be produced from St52 material weighing approximately 48kg, 231MPa stress was observed in the crash scenario and the structure has a safety factor of 1,53. For the cast carrier structure, which is planned to be produced from GGG50 material weighing approximately 46kg, 122MPa stress was observerd in the crash scerario and the structure has a safety factor of 2,62. In the modal analyzes carried out to understand whether the system will resonate under vibration, it has been observed that the carrier structure designed according to the two production methods is out of the range of 29 – 124 Hz, which is driving frequency of the engine. As the two structures examined meet the system performance, it was decided to improve the design of the cast structure by considering the cost, weight and reliability. With the design changes, the weight of the carrier structure has been reduced to 38kg and 8kg of lightening has been achived. As a result of the static analyzes carried out on the improved final carrier structure, unlike other structures, the highest stress was found as 192MPa in the bump scenario and the structure has a safety factor of 1,67. Within the scope of modal analysis, after the six rigid body modes, the natural frequency in the seventh mode was found as 214Hz. Since this value is out of the engine drive frequencies, it is concluded that the system will not resonate and will be safe.