Energy absorbing cab guards for log trucks. Issue 3 (2nd September 2021) - Lyons, C. Kevin
ABSTRACT: This article examines the performance of an existing log truck cab guard subject to impact from the load of logs shifting forward during sudden truck deceleration, and considers modifications to the cab guard to reduce the effect of impact. It was found that the logs impacted the existing cab guard with a load sufficient to reach the design displacement of 0.25 m and to exceed the yield stress in the foot and in the gusset for log truck decelerations greater than 32.5 m/s 2 . Increasing the cross section of the cab guard foot reduces the maximum stress found in the foot; however, this resulted in the maximum stress in the gusset increasing from the original design. Increasing the gusset thickness resulted in a slight decrease in the maximum stress found in the gusset, with little change in the maximum stress found in the foot. Increasing the yield stress of the steel did not change the stress distribution; however, this did result in the maximum stress found in the foot being below the new yield stress. Adding an energy absorbing pad to the cab guard improved all the performance metrics resulting in the maximum stress in the foot being well below the original yield stress, reducing the maximum stress in the gusset to near the yield stress, and reducing the displacement by almost a third.