A shock test system is a device used to subject objects to sudden and intense shock impulses to evaluate their resistance to shock and assess their durability and reliability. It simulates real-world shock events to test the performance and structural integrity of products.
1) Main components of a shock test system?
A shock test system typically consists of a shock table, shock generator, accelerometer sensor, control software, and data acquisition system. The shock table provides a stable platform for the test specimen, the shock generator delivers controlled shock impulses, the accelerometer sensor measures the shock response, the control software sets and controls the test parameters, and the data acquisition system records and analyzes the test data.
2) Application of shock test systems
Shock test systems are used in various industries including aerospace, automotive engineering, electronics, military, packaging, and consumer goods. They are employed to evaluate the robustness of products during transportation, handling, and operation to ensure their reliability and safety.
3) What types of shocks can a shock test system simulate?
A shock test system can simulate different types of shocks such as half sine wave shocks, sawtooth shocks, square wave shocks, and pyrotechnic shocks. These shocks can have specific durations, amplitudes, and rise times to replicate real-world shock events that products may experience during their lifecycle.
The advantages of a shock test system include:
- Providing controlled and repeatable shock impulses to accurately assess product durability and reliability.
- Simulating a wide range of shock events to mimic real-world conditions and identify potential weak points in product design or packaging.
- Assisting in the development of robust products that can withstand harsh shock environments and meet regulatory requirements.
- Enhancing product quality and safety by identifying and rectifying potential failure modes.
- Improving the overall efficiency of product development by reducing the risk of failure and the need for costly field testing.
To choose the right shock test system, consider the following factors:
- Desired shock specifications: Determine the required shock amplitude, duration, and waveform based on the intended application.
- Sample size and weight: Consider the size and weight of the test specimens to ensure they can be accommodated by the shock table and generator.
- Budget constraints: Select a shock test system that meets your performance requirements within the allocated budget.
- Regulatory compliance: Check if the system meets relevant industry standards and certifications.
- Supplier reputation and after-sales support: Choose a reputable supplier that offers reliable equipment and comprehensive customer support.
According to the survey, shock is the application of a high level of input impulse to a product over a relatively short period of time. The impact is a very complex physical process. But did you know that, like random vibrations, it has a continuous spectrum? At the same time, it is also a transient process that does not satisfy the steady-state random condition.
Usually, after the product is impacted, the motion state of its mechanical system will suddenly change, resulting in a transient impact response. Under the mechanical impact, the oscillation frequency of the product will become higher. But the duration is short, the initial rise time is obvious, and there are high-order positive and negative peaks. What we can tell you is that there is a decreasing exponential function around the peak response to mechanical shock.
We know that for products with complex multimodal characteristics, the impulse response consists of the following two frequency response components. The first is the forced frequency response component of the external stimulus environment applied to the product. The second is the natural frequency response component of the product during or after the stimulus is applied.
1）The physical angle of the test
On the other hand, from a physical point of view. The impact response of your product after it is impacted (i.e. the transient excitation) represents the actual impact strength of the product. If the instantaneous response range of your product exceeds its structural strength, your product will be damaged. This is not what we want to see.
But what you need to know is that the damage caused by product impact is not cumulative. But the peak damage is caused by the ultimate stress relative to the strength of the product structure.
You know, if the peak is breached. It will cause structural deformation, installation loosening, crack or even fracture, electrical connection loosening, poor connection, and fracture, making the product unstable. This peak damage can also change the relative position of each unit in the product, resulting in reduced or poor performance of the product, or worse, damage to the component or part, rendering it inoperable.
Linkotest designs and manufactures shock test systems including Mechanical Shock Test Machine, Bump Test Machine, Incline Impact Tester, and other products to meet your different impact testing needs. The following is the information we have some examples for your reference.
2）List of description
(1) Product failure caused by friction force increase or decrease or mutual interference between parts.
(2) The insulation strength of the product changes. This will cause the insulation resistance to decrease, and the strength of the magnetic and static electric fields will change accordingly.
(3) Product circuit board failure, damage, and electrical connector failure (sometimes the product is subject to shock, and excess parts on the circuit board may migrate and cause a short circuit).
(4) When the structural or non-structural parts of the product are subjected to excessive force, the product will produce permanent mechanical deformation.
(5) When the ultimate strength is exceeded, the mechanical parts of the product will be damaged.
(6) Accelerated fatigue of materials
As you can see from the above description, shocks can adversely affect the structural and functional integrity of the entire product. The extent of this adverse effect usually varies in degree and duration. For example, if the shock duration is inversely proportional to the natural frequency of the product, or if the primary frequency component of the input shock environment waveform is consistent with its natural frequency. It is likely to further increase the adverse impact on the structural and functional integrity of the product.
Therefore, in order to ensure that the product has good impact strength and works reliably and stably in the impact environment or after the impact. This is of great significance to our impact test. This method can be used to assess the structural and functional properties of a product under mechanical shock during its service life. However, this mechanism is generally limited to a frequency range of no more than 10,000 Hz and a duration of no more than 1.0 seconds. What we can tell you is that in most cases, the primary response frequency of the product does not exceed 2000Hz, and the response duration is less than 0.1 seconds.
Here are the test conditions for the shock test system, you can have a look.
1) Peak acceleration
We found that the magnitude of the peak acceleration can be directly correlated depending on the impact force applied to the product. Since most of the structure of the product is a linear system. But even a nonlinear system can be regarded as a linear system when the strain is small.
In this way. We can conclude that the response acceleration is proportional to the excitation acceleration of the product after the impact. In addition. It can be seen that in general, the greater the peak acceleration, the greater the damage to the product.
2) Pulse duration
The duration of the shock pulse is the interval during which the acceleration is maintained at the specified peak acceleration ratio. We understand that the impact of impulse duration on the product is very complex. In fact, its influence on the impact effect is related to the natural cycle of the system under test.
3) Number of impacts
We recommend that you do not need to repeat the test on the product. Because the impact mainly considers the impact on the ultimate strength of the product, rather than cumulative damage. However, to avoid accidents, you also need a certain number of hits.
In general, three consecutive shocks are required in each direction. In addition, you should be aware that the maximum response due to shocks may occur in the other direction. Yes, in the same direction as the excitation pulse or in the opposite direction. So, according to the general rules. Impact tests shall be carried out in each direction of the three axes perpendicular to each other. Therefore, we will conduct 3 × 6 = 18 impact tests in six directions.
As we all know, there are many devices that produce electric shock, and the electric shock test system is the most important one. Because it can not only generate the impact response spectrum and impact time history of heavy sites but also generate the nominal impact pulse waveform.
However, you need to understand that there are other devices besides electric shakers that can produce a nominal shock pulse waveform. Examples include free fall, compressed air, gas-liquid pressure, and changing momentum.
No matter what test equipment is used to make an impact, our requirements for them are the same. Please note that the requirements here are the same as the verification (calibration) requirements on the test bench. That is, without reference to the impact test equipment during unloading.