FIGURE 2 shows compression wave generation apparatus 101 to the left of split Hopkinson pressure bar 102 including input bar 103 connected via test specimen 104 to output bar 105. Compression wave 106,107 is generated by initially placing impactor bar 109 under a pre-load force by hydraulic actuator 108 (in the direction of arrow A) until fragile component 110 ruptures causing end 109a to impact input end 103a of the input bar 103. End 109a is guided and held adjacent end 103a by collar 111 welded to end 109a prevented from movement to the left by blocking system 112.