EVALUATION OF FORCE AND PARTICLE-VELOCITY AT THE HEATED END OF A ROD SUBJECTED TO IMPACT LOADING

A method to evaluate the force and particle velocity at the heated end of a rod subjected to impact loading is presented. The method is based on a characteristic impedance function determined by a set of parameters. With a given characteristic impedance function the force and particle velocity at the heated end can be evaluated from measured strains at two cross-sections of the rod. In order to evaluate the characteristic impedance function the rod is impacted by a hammer at one end and the heated end is free. The optimal set of parameters is determined by a procedure which minimizes the error, i.e. the evaluated force at the free end of the rod. The results show that the error obtained with the constant characteristic impedance function is considerable, whereas the error obtained with the evaluated characteristic impedance function is of the same magnitude as the error obtained for a test at constant temperature. Thus, with this method it is possible to evaluate the force and particle velocity at the heated end of a rod with the same accuracy as for a uniform rod at room temperature.