For heavy-duty test pieces, no support is required; for medium-sized test pieces, it must be placed on a flat, strong surface, and the test piece must be placed smoothly without any shaking; for light-weight test pieces, it must be tightly coupled with a strong support. The two coupling surfaces must be smooth and flat, and the amount of coupling agent should not be too much. The test direction must be perpendicular to the plane of the coupling. When the test piece is a long rod, a large-area plate or a bent piece, even if the weight and thickness are large, the test piece may be caused. Deformation and instability cause the test value to be inaccurate, so it should be reinforced or supported on the back of the test point.