How to use an impact tester

(1) Overview

This test machine is a simple-supported beam pendulum impact strength test machine, which can measure the impact strength of various non-metallic materials. Its impact energy is divided into two levels: 0.98J and 3.92J (usually 0.98J level), and its impact speed is 2.9m/s.

(2) Principle of experiment

ShouldTesting machineIt is to add impact bending load to horizontally placed samples to break the sample, and the impact of the material is measured by the work consumed per unit cross-sectional area. If the width in the middle of the sample is bcm and the thickness is dcm, and the impact energy consumed by the sample is AJ, then the impact intensity a of the sample is

A

a= ――――――

b・d

(3) Installation and debugging of test machine

1. The basic structure of the test machine is shown in Figure 1.

2. Place the test machine on a solid plane and adjust the three adjustment screws (2) on its base to make it horizontal.

3. The distance between the adjustment brackets (4) is 40.0±0.2mm.

4. CalibrationTesting machineAt the zero point of the dial, place the pendulum (5) in the pre-lift hook (9) position, and let it fall freely without putting the sample. The pointer (6) should point at the zero point of the scale line (10) (the outer ring scale line is 0.01J/grid). Otherwise, the adjustment nut (8) can be loosened, the position of the stop needle (7) can be adjusted repeatedly, so that the pointer points to the zero point of the outer ring scale line when the pendulum bell falls freely, so that the test machine has been adjusted.

(4) Test steps:

1. The sample should be taken in the vertical friction direction in the middle of the product. The length of the sample is 55.0±0.5mm, the width is 6.0±0.2mm, the thickness is 10.0±0.2mm (the actual thickness of the sample is less than 10.0). The surface in the width direction of the sample is the product compressed surface. Five samples were used for each test.

2. Correct the zero point of the test machine dial every time so that the pointer points to the zero point of the outer ring scale (0.01J/grid) when the pendulum falls freely.

3. Place the sample on the support of the test machine according to the method shown in Figure 3, so that the back of the notch is subjected to impact load. The impact blade is to be hit on the entire width line of the sample and aligned with the center line of the sample.

4. During the test, carefully loosen the lock hook to let the pendulum fall freely. The sample is subjected to impact load. Read the number of dials pointed by the pointer when the sample is broken, that is, impact energy A.

5. When the sample continues to crack in the gap, the obtained data is invalid and the sample is supplemented.

(5) Calculation of test results:

The impact strength of the sample is calculated according to the following formula:

A

a = ―――――

b・d

Where: a - specimen impact strength, J/cm²

A-Impact energy when the sample is broken, J

b―Width of the middle part of the sample, cm

d―The thickness of the sample notch, cm

Each test is based on the arithmetic average of the test results of 5 samples.

(6)Test machine maintenance:

Always keep the body of the test machine clean, apply a layer of anti-rust oil on the surface when it is not in use for a long time, and prohibit violent collisions and vibrations.