Trailer Design Guideline > Design
Loading situations
Trailer designs are often the result of experience and knowledge gained by manufacturing companies over the years, as well as the know-how of end users.
Good solutions are generally also applicable for lightweight vehicles produced in high-strength steel. However, high-strength steel enables new solutions, but may also require design changes in order to leverage its higher strength.
A typical trailer chassis consists of two longitudinal main beams manufactured from either standardized hot-rolled profiles or welded I-beams, along with a variety of cross-member profiles. Cross-members can be made from open profiles, tubes or box-section profiles, depending on trailer type. Floor members and different support profiles can also be attached to the chassis. The king-pin region of the trailer usually consists of a king-pin plate and some reinforcement profiles.
The potential for upgrading a trailer chassis is generally limited not only by its static load-carrying capacity, but even more so by fatigue and stability issues. Therefore, while finding a solution with matching load-carrying capacity to the existing design serves as a good starting point, it is essential to address these other technical considerations in order to have a vehicle with matching or improved performance. It is important to note that poor design or production quality can rapidly reduce the vehicle life span.
The dimensioning load case for a trailer chassis manufactured from mild steel is generally its load-carrying capacity with regard to permanent deformations, as shown in the illustration below. In a light-weight trailer chassis, where thicknesses have been reduced and working stress levels increased, the load-carrying capacity and service life are limited by fatigue, elastic deflections and stability.
Trailers subjected to different loading situations during service.
To achieve a successful upgrading it is important to take all loading situations into account,
a) Fatigue at frequent low stress loading cycles,
b) Elastic deformations when operating,
c) Load carrying capacity; no permanent deformations at maximum loading,
d) Stability when operating.
The information in this report is only applicable to SSAB’s products and should not be applied to any other products than original SSAB products.
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