초록
Purpose: This study was conducted to experimentally investigate the structural safety of and identify critical locations in a front-end loader under impact loads. Methods: Impact and static tests were conducted on a commonly used front-end loader mounted on a tractor. In the impact test, the bucket of the front-end loader with maximum live load was raised to its maximum lift height and was allowed to free fall to a height of 500 mm above the ground where it was stopped abruptly. For the static test, the bucket with maximum live load was raised and held at the maximum lift height, median height, and a height of 500 mm from the ground. Strain gages were attached at twenty-three main locations on the front-end loader, and the maximum stresses and strains were measured during respective impact and static tests. Results: Stresses and strains at the same location on the loader were higher in the impact test than in the static test, for most of measurement locations. This indicated that the front-end loader was put under a severe environment during impact loading. The safety factors for stresses were higher than 1.0 at all locations during impact and static tests. Conclusions: Since the lowest safety factor was higher than 1.0, the front-end loader was considered as structurally safe under impact loads. However, caution must be exercised at the locations having relatively low safety factors because failure may occur at these locations under high impact loads. These important design locations were identified to be the bucket link elements and the connection elements between the tractor frame and front-end loader. A robust design is required for these elements because of their high failure probability caused by excessive impact stress.