Estudo de rigidez torcional em um chassi space frame do tipo Baja SAE

Abstract

The validation of chassis torsional stiffness by computational methods became more current when developing new prototypes, mainly talking about off-road vehicles, that are susceptible to receive critical forces on the conditions of crashed terrains through which they pass. The rigidity of the structure can be divided into four subsets, being two stiffness in the forward with hourly twist and anti-clockwise twist, as well as the operation mode twice in the rear. The geometric tolerances of the structure are determinated based on the SAE Brazil standard. Relating the material resources available and their mechanical properties, SAE 1020 carbon steel tubes with a diameter of 31.75 mm and a thickness of 1.6 mm are used to maintain strength, mass reduction and cost. The three-dimensional geometry of the structure is modeled, converting it into a mathematical model using the finite element method, composed of tetrahedral elements. Applying torsional binaries on the forward with the maximums forces of the shock absorbers are obtained the angular deflections of the loaded points, being calculated the local rigidities of the chassis. The resulting generates front and rear torsional stiffness, which together produce the global torsional stiffness of the structure, representing your ability to strain by torsional forces. According to the bibliography, the Baja vehicles work with torsional stiffness between 750 and 1500 N.m/deg. A global torsional stiffness of 1871.83 N.m/deg is obtained, with the front and rear stiffness respectively at 3.77% and 40.33% above the upper limit of the theoretical reference and with maximum deformations at the front of 24.918 mm. It is considered that the addition of experimental and analytical methods may contribute to the aggrandizement of the studies realized.