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In general, the shocks we are looking at are the transient effects of high acceleration levels and short action times reflected in the product packaging system. The most typical example is a drop. However, as a professional institution that studies packaging testing, in our understanding, the scope of the impact is even greater. Moreover, with the different conditions encountered during the logistics process of transport packages, impact tests also have a variety of test methods.
The methods of impact testing can be divided into two categories from the purpose:
One is to examine the protection capabilities of packaging on products, including drop tests, horizontal impact tests, vertical impact tests, etc.
The second is to examine the tolerance of the product to impact hazards, including: product fragility test and so on.
From the test control methods and results can also be basically divided into two categories:
One method is to simulate various impact phenomena that may be encountered in the transport package during actual circulation, and to control the final velocity of the impact during the test. The so-called end speed is the speed of the transport package before the impact. Controlling the drop height is also a way to control the end of impact velocity. For freefall, v = (2gh)1/2, we can see that the drop height and the end impact velocity can be simply interchanged. We can simulate the hazards that packages are subjected to in the circulation process through the control of the laboratory.
Another method is to control the acceleration of the impact and the duration of the impact. According to this control method, we can reproduce the situation in the laboratory very accurately. This kind of control method is more complicated, in addition to the acceleration and duration, but also consider the impact of impact waveforms, impact response and other factors.
Drop test is a commonly used test method used to simulate the impact of the product in the logistics process - the packaging system. Drop tests also have several different methods, which simulate the different situations in the actual circulation process. But they all have some common basic requirements. One is that the release device does not have a significant effect on the test sample, and the other is that the drop platform must have sufficient quality and rigidity. According to the requirements of GB/T4857.5, the quality of the falling platform should be more than 50 times the quality of the test sample.
Free fall is one of the basic tests for transport packages. The main method is to release the package from a certain height, so that it falls to the ground in a free fall. The free fall test can be divided into face, corner, and angle, and examine the impact of different drop directions on the product-package system. Rotational fall is a term translated from the standards of Europe and the United States and other countries. The Chinese standard is collectively referred to as the drop test of large-scale transport packages. The main method of turning and falling is to support on one side or corner of the package on the ground or pad, lift the opposite side of the package or diagonally to a predetermined height, release it and drop it. There is a problem with turning and falling, that is, what package is suitable for this test method. The requirements for large-scale transport packages vary among different standards. This requires us to choose according to our actual situation. During the tipping test, the package is placed on the impact table in a predetermined state, and a horizontal force is applied at a position above the center of the package to allow the package to tilt freely. Tipping tests are stipulated in national standards and ISO, ASTM, ISTA and other standards, but their respective requirements have certain differences.
The horizontal impact is to collide the package with a flap at a predetermined speed according to a predetermined state. The baffle should be perpendicular to the speed of the package. In the national standards GB/T4857.11, IS02244, and ASTM D5277, the slope and pendulum impact tests are respectively stipulated. Both horizontal impact tests have their own characteristics. Horizontal impact tests are generally used to evaluate the ability of a package to protect a product against horizontal shocks. In the actual logistics process, the package is subject to horizontal shocks, such as car brakes, train formations, and so on.
Regardless of whether it is a drop or an impact, each product in the transport package can be reflected in an acceleration-time history. From the damage theory, the peak acceleration and impact speed change are the decisive factors that cause product damage. In the event of an impact, the softness and hardness of the ground and the size of the area will affect the strength of the impact. These effects can also be reflected from these two determinants.
The vertical impact tester consists of a guide rail, an impact table, a program generator, and an impact mass. During the test, the transport package should be tightly fixed on the impact table, impact the impact block together with the mass, and generate a predetermined impulse waveform through the program generator. The commonly used vertical impact test standard is ASTM D5487.
Controlled horizontal impact tests must be performed using a controlled level impact tester. The controlled horizontal impact tester consists of a trolley, a track, an impact mass, and a program controller. The package is placed on the trolley and the mass is impacted at a certain speed. The required shock pulses are generated by the program controller. The controlled horizontal impact test has many control parameters, which can control the impact end velocity, impact acceleration, impact time, impact velocity variation, and the shock waveform discussed earlier. From the standards used, there are ASTMD4003, GB4857.15, ISTA and other options.
Hazardous impact is not a separate test method. Shock hazards can be applied in the various shock tests described above. The so-called dangerous object impact is to place a specific rigid object between the package and the impact surface so that the package first contacts the object during impact, so that the package is subjected to more severe damage. There are no clear requirements for the fall of dangerous substances in our standards, but the ISTA standards clearly state the provisions for the fall of dangerous substances. The so-called drop of dangerous goods is placing various standard dangerous objects on the impact table of the test equipment and causing the package to fall onto dangerous goods. It simulates the ability of the packaging to protect products when the floor is uneven or there is foreign matter during loading and unloading. (To be continued)
Impact Test Method Impact is a common risk factor in the logistics process. It is the most direct hazard to the product packaging system. Therefore, in each standard system, even the company's corporate standards, must involve the impact test project.
February 03, 2019