On checking with the spring damper, leakage of the hydraulic oil and failure of the additional elastomer spring is found
(Fig. 2b). In some cases, the piston rod is flexural deformed. All these surveys indicate that there exist heavy load both on the
spring damper and the spring tower. Because 20,000–50,000 km is far from the spring tower’s design life, it is estimated that
low cycle fatigue occurred on it. Further load test and simulation is to be conducted for the quantification of the damage and
fatigue life