Split Hopkinson bar is a well-known device for mechanical characterization of materials under dynamicloading. The device can be compressive, tensile, and torsional or shear. The effect of dimensions of SHB inparticular the length to diameter ratio,L=D, of the bars has been the subject of some investigations overthe past several decades. However, no work has so far been performed on the forgoing ratio in torsionalSplit Hopkinson bar (TSHB). In this work, the length to diameter ratio of the input or output bar,L=D,isstudied by numerical simulation, theory through Lagrange diagram of the TSHB and experiment. It hasbeen found that forL=D>80, the incident, reflected and transmitted wavelengths obtained fromsimulations and Lagrange diagram are the same. This value ofL=Dis quite consistent with that usuallyrecommended for compressive and tensile versions of SHB. The numerical model of TSHB is validatedby Lagrange diagram and experiment
