This paper presents an analysis of factors essential to air spring and undercarriage design to determine their influence on air spring fatigue life. Two sets of factors were chosen for the investigation: those relating to the design of the air spring itself (cord angle, diameter difference) and those relating to the design of the undercarriage (lever length, eccentricity, lever eccentricity, inclination). A full factorial experiment, whereby interactions between all the factors are investigated, would demand 729 experiments. Using Taguchi methods, the number of experiments required is dramatically reduced, using only 27 experiments to determine the influence of 6 factors and 3 interactions. Taguchi analysis shows here that factors inherent to air spring design have a much greater influence on fatigue life than those factors inherent to undercarriage design. Interaction between these factors has also revealed that there is no optimal cord angle for all air springs.

Air spring manufactures use constant amplitude tests for the quality validation of air springs. The tests are very simple and the only information we get from them is that a spring is adequate if it passes the test and inadequate if it does not. One of the objectives of this article is to use these tests to make life predictions based on the standardised load spectrum. This prediction is made with force as the damage parameter. The second objective is to determine if it is possible to use experimental results obtained at one control parameter, e.g. force, to make life predictions for another control parameter, e.g. stress. With equations it is proved that such transformation is possible.

Growing environmental demands and higher fuel efficiency encourage the use of new light‐weight load‐bearing materials even for operation under rougher environmental conditions. Consequently, as the materials used in the vital load‐bearing components of the chassis, brake system or exhaust system are subjected to thermomechanical fatigue during the operation due to variable mechanical and thermal loads, it is crucial for design engineers and CAE analysts to understand the cyclic behaviour of new materials under such conditions. Here we have analysed the stress–strain behaviour of magnesium alloy AZ31 and the influence of variable thermomechanical loads. A uniaxially loaded flat specimen has been first mechanically loaded at −25°C. The temperature was then increased to 150°C whilst the variable mechanical loading remained unchanged. The tests have been strain‐controlled using a video extensometer. The stress–strain behaviour of the magnesium alloy AZ31 has been then investigated considering both variable temperature and variable mechanical load.