DEVELOPMENT AND VALIDATION OF A FINITE ELEMENT ANALYSIS MODEL USED TO ANALYZE COUPLING REACTIONS BETWEEN A TRACTOR’S FIFTHWHEEL AND A SEMITRAILER’S KINGPIN

Open Access
Author:
Shoffner, Brent William
Graduate Program:
Mechanical Engineering
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
None
Committee Members:
  • Moustafa El Gindy, Thesis Advisor
  • Kevin L Koudela, Thesis Advisor
Keywords:
  • FEA
  • kingpin
  • Fifthwheel
  • Coupling
Abstract:
Visual inspections of selected semitrailers during routine equipment checks revealed that the kingpin bent 180 degrees from the direction that the semitrailer is towed. Confirmation from semitrailer repair facilities found that in some cases the semitrailer’s supporting structure developed unexpected cracks. These cracks were not thought to be age related but were most likely caused by high stresses from coupling. A literature search found no valid documented kingpin coupling tests and determined the SAE J133 kingpin loading requirements were incorrect. Previous reports relating to kingpin impact testing only tested the kingpin itself and not the kingpin supporting structure on the semitrailer or employed vague descriptions of actual test procedures. The development of a Finite Element Analysis (FEA) model of the tractor-semitrailer coupling determined that high coupling speeds would overload the kingpin-fifthwheel structure. The FEA model also allowed researchers to determine that a damping system would lower the forces at the semitrailer’s kingpin and tractor’s fifthwheel interface to an acceptable magnitude equivalent to forces experienced during normal operations. To begin the modeling, the kingpin supporting structure consisted of rigid elements. Validation of the FEA models was provided through two separate sets of tests. A coupling test was conducted at the Applied Research Laboratory (ARL) at the Pennsylvania State University. The FEA model gave predictions of the tractor deceleration during coupling tests within 10% of the measured decelerations at various impact speeds. The other set of validation tests was conducted at the Mack Trucks facility in Allentown, Pennsylvania. The FEA model was used to predict tractor CG decelerations for a heavy weight trailer to within 10% of the test data. The original tractor-semitrailer coupling FEA model was refined to include an elastic kingpin supporting structure. The elastic kingpin supporting structure model was compared to the original rigid kingpin supporting structure model; the elastic simulation was within 3% difference when compared to the original Mack Trucks rigid model. The modified semitrailer model was used to predict standardized SAE J133 vertical and horizontal kingpin coupling loads in order to calculate the stress distribution within the kingpin supporting structure. The simulations and validation tests provided information to develop a fifthwheel damping system. Preliminary design concepts were simulated using the validated coupling FEA model to provide an optimized set of parameters. The implementation of the translational fifthwheel spring/damper system in the simulation resulted in a considerable reduction of impact force and tractor decelerations. The simulations and measured results have provided enough data to facilitate the detailed design of a damping system prototype.