A fatigue testing method of actual car body structures under concentrated load instead of uniformly distributed load is studied. (1) The test under a concentrated load is able to simulate a state of uniformly distributed load by applying a four-point bending moment to a car body. (2) The stresses of side plates and carrying loads of spot welds near the supporting part of a car body are in fair accordance with those under uniformly distributed load. Judging from the above results, fatigue test of a car body can be carried out by making use of the concentrated load.
