Lawrie Technology, Inc. has been engaged in composite product development since 1992 emphasizing applications that take advantage of its state-of-the-art, 4-axis filament winding and pultrusion capabilities. Custom built, bi-directional, electronic fiber tension control assists with the CNC winding of coupling geometries. Finite element analysis of optimized structures and processes complement strong analytical capabilities. Prior helicopter developments have included Boeing tension-torsion straps with current activity in the area of active blade shape control and avoidance of retreating blade stall. Tension-torsion straps are used to sustain large blade centrifugal forces while simultaneously twisting once per cycle to follow the blade pitch angle. Conceptually these are similar to couplings with the stiff, strong attribute being tension rather than torsion
