Development of a pultruded FRP composite material ROPS for farm tractors

The goal of this research was to explore the feasibility of fabricating a fixed-structure ROPS (rollover protective structure) for farm tractors from an FRP (fiberglass reinforced plastic) composite material. Evaluating the strength of proposed joint designs for the base and the upper corners of the FRP ROPS was the focus of this study. Three factors were investigated: base fixture strength for connecting the ROPS to the tractor, upper corner fastening strength, and FRP failure mechanisms under static loading. Results indicate the need for a well-bolted mounting connection. Also, the failure modes at bolted upper corners of an FRP ROPS were related to where bolt holes are located. Additionally, long cantilever beams similar to the vertical members of a ROPS absorbed energy well without significant lengthwise fiber failure. Failures observed were only at the base, rather than in the localized matrix failure that occurs at the loading point of shorter beams. When the full ROPS was loaded to failure, it exhibited three shear breakthroughs of matrix material at bolt holes before reaching its ultimate load strength at 53,370 N (12,000 lbf). An ultimate performance comparison to be evaluated is whether an FRP ROPS has equal or better impact energy absorption performance than a steel ROPS and whether it deflects no further than a steel ROPS element with an acceptable amount of deformation. Damage tolerance that takes into account changes in strength of an FRP ROPS due to tools and other objects striking it must be considered. With appropriate impact characteristics factored into a design, the value of FRP composites for ROPS is expected to reside in longevity and lower manufacturing costs.