Package transport testing is the process of simulating a transport unit (i.e., a whole transport package) encountering a range of anticipated test dangers using laboratory techniques. When our items are in transit, the following environmental variables can affect how well they hold up.
Figure 1.1 Transportation unit circulation process
1. What are the advantages of testing our solar products in a simulated transport environment?
Because solar items are susceptible to impact or even damage during shipping due to stress, vibration, temperature and humidity changes, radiation, and harsh human activity, among other variables, packaging’s primary purpose is to safeguard photovoltaic products. A sensible packaging structure design can reduce the need for secondary packing, transport packaging, and the use of packaging materials while also protecting the PV module by increasing the rigidity and strength of the packaging.
Transport packaging tests are therefore very important for photovoltaic products like solar modules, as seen in the examples below.
- lessen the possibility of product damage owing to poor packaging during shipment;
- Reduce and save on logistics expenses;
- Reduce the time spent developing packaging;
- Decrease and end claim disputes;
- Provide transportation businesses with technical reference information;
- Improve corporate reputation, abide by national requirements, and make packaging more environmentally friendly.
The testing standards that are frequently used for packaging and shipping include ASTM D4169, ISTA3E, IEC62759-1, and others. When combined with packaging and transportation testing in the course of daily work, test standards, the arrangement of test items in the order, test intensity, acceptance criteria, etc. will alter. Part of the test items is introduced as follows.
2. What vibration testing is performed on solar items during a simulated transport?
The majority of the vibration that photovoltaic products experience during transportation and real usage, in response to market demand, is random vibration (rather than sinusoidal vibration). For instance, during land transportation, the vibration is caused by vehicles traveling on uneven roads, and during maritime transit, the vibration is caused by shifting sea waves on ships. The product’s vibration resistance can therefore be more accurately assessed using a random vibration test.
Random vibration is much more severe, realistic, and practical than sinusoidal vibration at simulating the effects of the above vibration because it can excite the product at all frequencies simultaneously and has a wider frequency domain than sinusoidal vibration. Sinusoidal vibration can only simulate the effects of the above vibration at specific frequencies or with a continuous spectrum. Furthermore, compared to sinusoidal vibration, random vibration is significantly more straightforward and effective for studying a product’s dynamic features and the transfer function of a structure.
Random vibration, like sinusoidal vibration, can damage the connection, installation, and fixing of the product by causing wire friction, loosening fasteners, and jamming moveable parts. In the PV product structure, excessive random vibration excitation stress can lead to cracks and fractures, especially in extreme resonance states.
Due to the cumulative damage brought on by alternating strains, long-term random vibration might result in fatigue damage to the module structure. Random vibration can also result in poor contact, solder joint failure, and wire breakage, which can impair product functionality and worsen or even cause a module to fail.
The requirements for random vibration are currently being refined and matured over time. The primary random vibration test conditions (severe level) are determined by the test frequency range (Hz), power spectral density (g2/Hz), the frequency spectrum of the power spectral density, the total root mean square acceleration (Grms), and the test time, which are made up of four parameters. Common standards such as IEC62759-1, ISTA, etc., use these parameters.
The frequency range, which we presently frequently evaluate in the region of 1-200 Hz, is defined as the frequency between the greatest frequency and the lowest frequency at which the vibration of the product mounting platform creates an effective excitation on the product. The PSD power spectral density (also known as the ASD acceleration spectral density) and spectrum of power spectral density calculated in the appropriate frequency range serve as indicators of random vibration.
The energy per frequency is known as the power spectral density (also known as the acceleration spectral density), and the distribution of vibrational energy over the full frequency range is known as the spectrum of power spectral density (also known as the acceleration spectral density spectrum).
The lab has also carried out numerous pertinent experiments for the random vibration of PV cells and modules, as can be seen in Figure 2.1 below, which depicts the random vibration profile of Hua laboratory twice for various total masses of PV module packaging and transportation units.
Figure 2.1 (a) Vibration spectrum of single glass module packaging and transportation unit
Figure 2.1 (b) Vibration spectrum of double glass module packaging and transportation unit
As can be seen, the curve fluctuations are more uniform in the low-frequency range than they are in the high-frequency range, where the mass of the packaging unit curve fluctuations are higher and hence correspond to higher vibrational energies. The total root means square acceleration (Grms) value is additionally frequently employed for test error control and detection, as well as in accordance with the weight, volume, and dynamic properties of the test sample to choose how much thrust (power) of the shaker. The total root means square acceleration (Grms) value currently needs to be at least 0.49grms in accordance with the IEC62759-1 standard, and the reference parameters are established as shown in Table 2.1.
Table 2.1 IEC62759-1 standard, total root mean square acceleration (Grms) value requirements
In order to better serve our client’s needs, we can additionally adjust the total root mean square acceleration (Grms) value and test duration in accordance with different test standards or requirements.
Random vibration test
3. What shock testing is performed on solar items during a simulated transport?
Impact tests are used to analyze a product’s resistance to external impact environments by simulating the PV module packaging unit in the shipping process, where it may primarily experience impact effects and shock waves in the instantaneous transient energy exchange. In order to effectively assess the product’s dependability and determine whether it can fulfill the role of protecting photovoltaic modules after an impact, it is important to understand the packaging structure’s weaknesses as well as the strength of the packaging material and how impact resistance, drop resistance, and other characteristics appear. The Linkotest laboratory is equipped to conduct the following common impact tests while packaging units are being transported
Figure 2.3 Rotating edge drop test
1) Vertical shock test
The vertical shock test simulates the effects of typical truck travel on components during road transport by using the vertical vibration test system of the Road Package Transport Laboratory.
Figure 2.4 Vertical shock test
Refer to standard DIN EN 60086-2-27 if in accordance with IEC62759-1. The test system is started, and 100 half-sine wave shocks are applied vertically, with an acceleration of 10g and a pulse duration of 11ms. The shock test pattern is shown in Figure 2.5. The package transport unit to be tested is placed on the vertical table and fixed (Figure 2.4), the data collector of the shock table is connected, and the test system is started.
Figure 2.5 Vertical shock spectrum
Table 2.2 displays the time domain analysis of one of the shocks. When the charts are combined, it is clear that the acceleration, pulse duration, and velocity change of the actual shock correspond to its upper and lower limits.
Table 2.2 Time Domain Analysis of Vertical Impact
2) Horizontal impact and inclined impact
The reference standard is ASTM D5277, and the horizontal impact test equipment is employed in accordance with standard IEC62759-1 to simulate the impact of sample displacement brought on by the sudden braking of the vehicle during the road transportation of the PV module packaging unit. The reference standard is ISTA 3E, Test Block 2, and the inclined impact is used to simulate the impact of forklift handling, among other things
Figure 2.6 (a) Horizontal impact test
Figure 2.6 (b) Inclined impact test
For the horizontal impact, start the test at a speed of no less than 1.1 m/s; while running, first apply a 0.3 g initial deceleration, then gradually increase the deceleration to eventually reach 1 g or transport unit breakage, in order to form a pulse duration of 350 ms half-sine wave; and finally, adjust the impact surface to repeat the test procedure
In conclusion, it can be seen that the role played by the function of qualified packaging in the logistics and transportation of photovoltaic products is to protect goods in the process of transportation to maintain the state of the product is not damaged, convenient transportation, loading and unloading, storage, convenient stacking, and counting, thus ensuring the integrity of the photovoltaic module packaging unit.