THE USE OF DYNAMIC STRAIN RECORDS TO ESTIMATE THE FATIGUE LIFE OF A SEMI-TRAILER CHASSIS

The paper describes an experiment in which the strain was recorded at critical points on the chassis of a 16 ton gvw semi-trailer, operating on various road surfaces. Vertical acceleration was also recorded in the region of the suspension. Statistical analysis of the records in terms of design factors and load spectra is then used to determine suitable maximum stress levels for the maximum static load and then to estimate the fatigue life. Since many chassis are of welded steel construction, the s-n curves used are appropriate to the class of joint. Miner's law is used to estimate the cumulative effect of the various load spectra. The final section draws some general conclusions on the effect of increasing static stress levels on the fatigue life, and describes methods of weight reduction in the chasis while maintaining an adequate fatigue life. /Author/ /TRRL/