What is the mechanical impact test? General testing standard for mechanical impact test

Date：2021-07-28 13:37:00 Views：2919

Introduction to mechanical impact test

The mechanical impact test mainly simulates the impact effect that the equipment and its components may encounter during transportation or use, and analyzes the ability of the product to withstand the external impact environment through the instantaneous transient energy exchange of the shock wave. The purpose of the test is to understand its structural weakness and functional degradation, which is helpful to understand the structural strength, appearance, impact resistance, drop and other characteristics of the product. Effectively evaluate the reliability of products and monitor the consistency of products in the production line.

Mechanical impact test is applicable to the monomer, packaging and transportation of electronic products.

Mechanical impact test method

(1) Standard pulse impact test method

In this method, an impact pulse waveform is specified in advance, and the tolerance zones of various pulse waveforms are specified. Jr1af-dc12v then carries out impact tests of various severity levels according to the specified peak acceleration of pulse waveform, pulse duration J, pulse times, etc. Because this kind of impact pulse is easy to be generated by test equipment in the laboratory, and this method can better simulate the mechanical damage caused by impact in the actual use environment, this test method is widely used at home and abroad. For example, IEC standard iec68-2-27ea "impact test method", national standard g Ⅳ T2 roller 3.5-95ea: "impact test method", GB / T Λ 6-95eb: "impact test method", gjb360. "- 87: Test Method for medium impact (Specified Pulse), GJB150, 18-86 impact test method, etc.

(2) Shock response spectrum test method

Shock response spectrum is usually referred to as "shock spectrum", which is an important concept widely used in engineering. The International Electrotechnical Commission (LEC), the technical committee of the international organization for Standardization (ISO) and the national standards of China have all taken shock spectrum as a method to specify the impact environment. This is a relatively new, scientific and reasonable test method. In this method, the impact response spectrum is used to express the impact of impact motion on product structure, that is, the impact response spectrum is used to study the damage ability of impact motion on product structure. It is very useful in determining the strength of product structure. This test method can be easily and conveniently carried out on a random shaking table. Foreign countries with relatively developed industry have already adopted the test method of "specifying a shock spectrum" to carry out impact test. Some domestic units have also done some work on the test method of "specifying a shock spectrum" in the early stage. Runqian is actively promoting this test method.

(3) Special impact test method

This method specifies the structure, technical requirements, operation method, movement form and sample installation mode of the impact machine in the form of specifications. As long as the operator works in accordance with the specifications and completes the test procedures in the specifications, even if the test results meet the standard requirements. This test method is mainly used for impact test of motors, electrical appliances and electronic equipment used on ships. Because the general volume and mass of motors, electrical appliances and electronic equipment used on ships are relatively human, if the above two methods are used for the test, they will be limited by the sample volume and mass, which will have a great impact on the test results. Therefore, it is more convenient to specify a standardized test method. Among the three test methods, the standard pulse test method is widely used and will be used in a considerable period of time in the future. Shock response spectrum test method is an advanced, scientific and reasonable test method. It can not only test the peak acceleration, pulse duration and pulse waveform accuracy of the sample, but also test the mechanical characteristics of the sample itself. Therefore, it is an ideal test method required by the future development trend. As a standard, the special impact test method has some limitations in the form of impact test for products, but it is still used at home and abroad to conduct impact test for large products and ship equipment.

Inspection standard of mechanical impact test:

Environmental testing of electric and electronic products Part 2: Test methods Test Ea and guidelines: impact GB / T 2423.5-1995 / IEC 60068-2-27:1987

Military equipment laboratory environmental test methods Part 18: impact test GJB 150.18a-2009

General specification for military communication equipment GJB 367a － 2001

General specification for military computer GJB 322a-1998

General specification for military electronic test equipment gjb3947a-2009

General specification for electronic measuring instruments GB / T 6587-2012

Test methods and procedures for microelectronic devices GJB 548b-2005

Test methods for electronic and electrical components GJB 360b-2009

Rail transit rolling stock electronic devices GB / T 25119-2010 / IEC 60571:2006

Environmental test and impact test of ship electronic equipment GJB 4.9-1983

Impact and vibration test of rail transit rolling stock equipment GB / T 21563-2008 / IEC 61373:1999

Technical indexes of impact test include: peak acceleration, pulse duration, velocity variation (half sine wave, back peak sawtooth wave, trapezoidal wave) and waveform selection.

The mechanical impact test mainly assesses that the product shall be able to withstand the impact capacity of the specified severity level and the integrity of the product structure and function. During the mechanical impact test, the tested sample shall be directly fastened to the table or fastened to the table through the fixture.

Common mechanical shock waveforms are: half sine wave, back peak sawtooth wave and trapezoidal wave. Manufacturers and users can carry out mechanical impact test of corresponding waveform according to the actual use of their own products.

Half sine wave: half cycle of sine wave.

Back peak sawtooth wave: asymmetric triangle with short falling time.

Trapezoidal wave: symmetrical trapezoid with short rise and fall time.

Summary of relevant issues:

1. What test equipment is used for mechanical impact test?

For small-scale mechanical impact test, it is applied by vibration test-bed, and for high acceleration mechanical impact test, it is usually applied by special high acceleration impact test-bed;

2. How many directions are mechanical impact tests usually done?

Generally, the positive directions of three mutually perpendicular directions are 6 directions in total. You can also make three positive directions (x, y and Z directions) according to your own situation. Generally, the impact times in each direction are 3 times;

3. Is it necessary to energize the test during the mechanical impact test?

Generally, the test is conducted without power supply, and there are also special cases. For example, the performance test is required for automotive electronic equipment during mechanical impact test;

4. How does the mechanical impact test fix the sample to the table?

In general, if the product is relatively rigid, the laboratory has special pressure bars and strips that can be fixed directly. For some circuit boards or components, the manufacturer needs to make fixtures to fix them;

5. What are the test parameters of mechanical impact test?

Waveform, acceleration and pulse duration of impact

6. Which products need mechanical impact test?

Electrical and electronics, military equipment, rail transit, wind power equipment, ship equipment, power equipment, photovoltaic equipment, automotive electronics, meteorological instruments, intelligent equipment, etc.