Analysis and testing of the thermal design of the electrical package in the U.S. Army's Upgraded Logic Module (ULM)

Abstract

The U.S. Army has developed an Upgraded Logic Module (ULM) for use in its Infantry Direct Fire Simulator System (IDFSS). It is designed to analyze data collected from associated instrumentation according to prescribed programming, to report results back to the system control via a telemetry interface, and it can be backpack mounted. The thermal environment existing at Ft. Hunter Liggett, Ca. (the primary operating environment for the ULM) during the summer will add an abnormal thermal load to the ULM operating environment in the backpack. A mock-up of the actual ULM was built to model the heat dissipation of all the components and tested in different environments using extreme power consumption rates. The actual ULM was tested with typical power consumption rates and various environmental temperatures, including solar loading. Under typical operating conditions, the ULM will remain within manufacturer's tolerances for individual component temperatures. However slight increases in power consumption rates will severely stress the reliability limits of certain components, and the reliability of the entire system cannot be predicted.