Thesis (MScEng)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: The aim of the thesis is to compare results obtained from a finite element analysis method (FEM) to experimental results of a 12.2m long semi-trailer driven off-road. Semi-trailers are of great importance in the transport industry. Furthermore, the need to obtain optimum and reliable semitrailers in this crucial stream of industry is indispensable. The work focuses on comparing the two results so that the finite element method may be used as design analysis and redesigning tool as a substitute to testing. The semi-trailer was driven on a relatively rough off-road at different speeds, at 70kmlh, 50kmlh and 40kmlh loaded with about 12 tonnes of brick pallets. The forces at the suspension of the semitrailer and strains at different parts were measured with the help of strain gauges and other data acquisition equipment. A finite element model of the semi-trailer was modelled in Nastran for Windows. The trailer parameters in the finite element were tuned to curve fit the test results. A comparison of the two /' results was made based on the average of absolute values and standard deviation, to verify the validity of the finite element model. / AFRIKAANSE OPSOMMING: Die doel van die tesis is om die resultate wat verkry is deur eindige element metodes (EEM) met eksperimentele resultate van 'n 12.2 m lang leunwa wat bestuur is op 'n grondpad te vergelyk. Leunwaens is baie belangrik vir die vervoer industrie. Verder is die behoefte om optimum en betroubare leunwaens in die industrie te vervaardig baie nodig. Die werk fokus daarop om die 2 resultate te vergelyk sodat die EEM gebruik kan word as ontwerp analiese en herontwerp gereedskapstuk en as 'n vervanging vir toetsing. Die leunwa was op 'n redelike rowwe pad teen verskillende snelhede nl. 70km/h, 50km/h en 40km/h met 'n 12 ton baksteen vrag gery. Die kragte by die suspensie van die leunwa en die vervorming by verskillende onderdele is gemeet met behulp van rekstrokies en ander data versamelings toerusting 'n Eindige element model van die leunwa is gemodelleer in "Nastran for Windows". Die sleepwa parameters in die eindige element model is verstel d.m.v krommepassing van die toets resultate. 'n Vergelyking van die 2 resultate is gebasseer op die gemiddelde van die absolute waardes en standaard afwykings, om die geldigheid van die eindige element model te kontroleer.