Numerical simulation of an English equestrian Saddletree

A thesis submitted in partial fulfilment of the requirements of the University of Wolverhampton for the degree of Master of Philosophy.The manufacture of horse riding saddlery in the UK is centred in Walsall in the West Midlands. The local industry faces stiff competition from cheap imports in local markets and dwindling exports to international markets. To continue to provide affordable high end products, which the local industry is reputed for, it is essential to develop an understanding of the functional and performance requirements of the saddletree based on scientific and engineering methods thereby laying a foundation for a methodical approach to product development. Through the measurement of surface data from a physical artefact, a 3 dimensional CAD geometrical replica of the English jumping saddletree was developed. Assumptions for the loading and boundary conditions identical to the user environment were obtained from available literature on the movements of the horseback, parameters for a jumping horse, saddletree test data, and, interface contact measurements acquired using a pressure mat. In addition, material properties data were obtained from available literature. Nonlinear static numerical models were subsequently developed and parametric studies were performed to determine the relationship between the deformation of the saddletree and the bending loads. Furthermore, nonlinear transient dynamic numerical models were developed and parametric studies performed to determine the response of the pommel to impact loads. The models were found to be sensitive to loading, material, and geometric parameters. From cantilever tests, the stiffness of the saddletree was found to be between 3.63 N/mm and 4.68 N/mm, and the steel reinforcement plates increased the stiffness by a factor of up to 2.3 times. Simply supported, the stiffness of the saddletree was between 526.62 N/mm and 596.16 N/mm, and the steel reinforcement plates increased the stiffness by a factor of up to 5.5 times. In addition, the simply supported models were sensitive to the wood laminate stacking sequence. Furthermore, the dynamic models showed that the steel reinforcement plates dampened the oscillations in the pommel after impact with a rigid body at 7 m/s, 8.5 m/s, and 10 m/s. The numerical cantilever models were validated with experimental data while interface pressure mat measurements validated interface contact stresses between the deformable bodies and the rigid body surfaces. Interface pressure mat results exhibited pressure hot spots and uneven load distributions underneath the saddletree. Peak and average pressures were 82.7 KPa and 15.4 KPa respectively, representing 16.2 % and 10.0 % error in comparison with the contact stresses obtained from the numerical models. Compression-flexure tests complemented the dynamic models. The steel reinforcement plates were observed to protect the pommel from delamination which was the principal failure mode of the wooden pommel; however, the reinforced pommel failed in flexure. From the simulations and tests performed, it was evident that there is a stiffness mismatch between the saddletree and the horseback which is undesirable. In addition to this significant conclusion, it has been shown that the steel reinforcement plates have a significant effect on the stiffness of the saddletree and do not protect it from failing. Hence, their continued use in the design and manufacturing of the English jumping saddletree is not recommended. Invaluable knowledge gained from the research allowed the definition of the performance attributes in a materials selection process ensuring the choice of potential material candidates to guarantee the optimal performance of the saddletree. Finally, the findings were incorporated in the development of a new concept design for next generation English saddletrees