A flexible two-axis servo-hydraulic system is used to determine the fatigue strength of car seats. It features a height-adjustable load frame, movable actuator, horizontal sliding table, adjustable seat retainers and a T-slot table. The flexible mounting of the pressure element and the sliding table allow simultaneous vertical and horizontal acceleration loads to be simulated. The system can easily be reconfigured to test other complex-shaped components in one or two axes.