**Impact test** is to measure the ability of materials to resist high-rate impact. Impact resistance can be obtained by calculating the amount of energy that causes test specimen failure. In general, there are two kinds of testers for impact resistance: free-falling dart impact tester and pendulum impact tester,conforming to different international standards.

**FDI-01 Falling Dart Impact Tester** is designed to measure impact resistance property of plastic films, sheeting, paper and foils. It is based on free falling dart method and equipped with LCD display.

### Principle

Before starting the test, choose test method, and estimate an initial mass and m. Start the test. If the first specimen fails, decrease the mass of the falling dart by m. If the first specimen is not a failure, increase the mass of the falling dart by m. Continue the test according to this rule. In brief, increase or decrease by m according to whether the former specimen is a failure or not. After 20 specimens, calculate the total number of failed specimens N. If N equals to 10, the test is over. If N is less than 10, add specimens and continue to test until N equals to 10. If N is greater than 10, add specimen and continue the test until the number of non-failure specimens reaches 10. Then the tester calculates the test results automatically according to specific formulas