REPORT 1 LAB G CUSHION CURVES

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Michigan State University *

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410

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Mechanical Engineering

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Feb 20, 2024

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LAB G - CUSHION TEST OBJECTIVE: Packaging cushion curves are critical in the design and manufacture of packaging materials. They are used to test the effectiveness of cushioning materials in protecting package contents during transportation and handling. These curves help designers to simulate real-world transportation conditions and identify the optimal level of cushioning required to prevent damage and breakage. The cushion curves test follows the ASTM D642 standard, which involves dropping weights on a cushion and measuring the resulting deceleration forces. The data collected is used to create curves that show the relationship between deceleration forces and the weight of the dropped object. This test helps designers to identify the effectiveness of different cushioning materials and determine the optimal level of cushioning required to protect package contents. The cushion curves test has several objectives, including learning how to use the equipment and understanding the test method. It also involves comparing the tested material to a commonly used cushioning material, EPS. This comparison helps designers to determine the relative effectiveness of different cushioning materials and make informed decisions about the materials to use. Overall, cushion curves tests are essential in the design and manufacture of packaging materials. They provide designers with a repeatable testing method to evaluate and improve cushioning materials, test packaging designs, and optimize supply chain logistics. By identifying the optimal level of cushioning required to protect package contents during transportation and handling, cushion curves tests help minimize damage and breakage, reducing costs and increasing customer satisfaction.

LAB G - CUSHION TEST PROCEDURE: To begin, power up the equipment. Turn on the coupler, located between the screen and computer in the photo above. If you don't turn it on first, you will get an error (figure 1). Next, turn on the computer and open the program on the desktop called TP3. When TP3 opens, the system defaults to the conditions that were in effect the last time it was used. Press the red power button on the left side of the Control Panel and turn on the velocity meter above it. Figure 1 Prepare the cushion tester for a drop from 18 inches. Remove any weights and clamps attached to the platen. Place a test cushion under the platen and center it. If necessary, attach the hoist to the platen by pressing the blue HOIST ( ˅ ) button on the control panel until the hook engages the peg on the right side of the platen. Press and hold the BRAKE RELEASE and ARM buttons with one hand, and with the other hand, press and hold HOIST ( ˄ ) to raise the platen a few inches. Release all buttons when the platen is done moving. Center the PRACTICE foam pad under the raised platen. Press and hold the BRAKE RELEASE and ARM buttons with one hand. With the other hand, press and hold HOIST ( ˅ ) to lower the platen. Release all buttons when the platen is resting on top of the cushion. Figure 2 Adjust the position of the U-shaped electric eye that is mounted on the right back pole of the cushion tester, raising it high enough so that the flag attached to the back of the platen completely passes through this sensor just before impacting the cushion. Use the large round knob on the right front guide rod to adjust the platen drop height. Raise the stop so that the platens fall about 18 inches. Press the BRAKE RELEASE and then the ARM buttons. Once both switches light up, Power Off Power On

LAB G - CUSHION TEST release the BRAKE RELEASE button but continue to hold the ARM button. While doing so, press and hold HOIST ( ˄ ) with the other hand. Raise the platen a few inches, enough so the velocity flag attached to the back of the platen is above the U-shaped electric eye. Push the red RESET button on the velocity meter. The velocity meter records the speed whenever the flag passes through regardless of direction. Figure 3 The velocity meter should always be reset when the flag is above the U-shaped eye. To drop the platen, continue to press and hold the BRAKE, ensuring both the BRAKE and ARM buttons are lit, and press and hold HOIST ( ˄ ) to raise the platen. When the platen reaches the stop, the hook will disengage, and the platen will fall. A switch will automatically stop the hoist, so you don't have to worry about releasing the HOIST ( ˄ ) until after the impact. Wait until just after the initial impact before releasing the ARM button. The velocity meter will display the actual impact velocity. Compare this to the target impact velocity for an 18-inch free fall. Reattach the hoist to the platen by pressing the blue HOIST ( ˅ ) button on the control panel until the hook engages the peg. Repeat the steps as needed to raise or lower the drop point to make the calculated velocity and the actual impact velocity agree within ±5 in/sec. To configure TestPartner software to capture a shock pulse, first, click on the RECORD/RECORDING SETUP tab located on the left side of the screen. Then, enter the following recording parameters using the mouse and/or keyboard: Recording Setup of 100 ms, Trigger level of ± 1%, Trigger Channel of 1, Trigger Polarity set to Bi-Polar, Channel to Edit of 1, and Filter set to Auto. Click OK to make these parameters active. Once the software is configured, perform drop tests on the cushion. Center a new Polyethylene (PE) test cushion under the platen, and if necessary, press and hold the BRAKE RELEASE and ARM buttons with one hand while pressing and holding HOIST ( ˄ ) with the other hand to raise the platen a few inches. Release all buttons when the platen is done moving. Press the BRAKE RELEASE and ARM buttons and continue to hold the ARM button while pressing and holding HOIST ( ˄ ) with the other hand to raise the platen a few inches. Then, push

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LAB G - CUSHION TEST the red RESET button on the velocity meter. In the TP3 window on the computer screen, click the ACQUIRE DATA tab. When you see the cartoon image of your TA tapping their foot, you are ready to make the drop. To drop the platen, continue to press and hold the BRAKE, ensuring that both the BRAKE and ARM buttons are lit, and press and hold HOIST ( ˄ ) to raise the platen. Once the platen reaches the stop, the hook will disengage, and the platen will fall. Wait until just after the initial impact before releasing the ARM button. The air brakes will then engage and catch the platen after the initial impact. Reattach the hoist to the platen by pressing the blue HOIST ( ˅ ) button on the control panel until the hook engages the peg. TestPartner should have captured the shock pulse. Record the "peak G" off this shock pulse and enter it in Table 2 under Drop #1. The peak G is displayed at the top of the graph (Max G's) or can be obtained using the scales on the graph. Repeat this process four more times onto the same cushion and record the peak G for each drop in Table 2 as Drop #2 through Drop #5. Since the weight dropped on the cushion is only 12.5 lbs. (the weight of the platen), there are no external weights attached to it. To perform drop testing on a cushioning material, the first step is to configure the TestPartner software to capture a shock pulse by setting recording parameters such as recording setup, trigger level, trigger channel, trigger polarity, channel to edit, and filter. Once the software is ready, center a new Polyethylene test cushion under the platen and perform drop tests using a specific set of steps. If required, change the weight by placing a 12.5 lbs. external weight on top of the platen and adjusting the drop height accordingly. Record the peak G's for each drop in a table. If the drop height needs to be changed, calculate the expected impact velocity, and adjust the platen drop height accordingly. Finally, turn off the equipment by lowering the platen onto the cushion, turning off the power button on the control panel, turning off the velocity meter, closing TestPartner, turning off the computer, and turning off the coupler.

LAB G - CUSHION TEST DATA, ANALYSIS, AND OBSERVATIONS: 1. Calculate the impact velocity expected in a free fall from 18": 𝑉 𝑖 = √2𝑔ℎ Where: V i = impact velocity (in/sec) g = acceleration due to gravity = 386.4 in/sec 2 h = target drop height (inches) = 18” 𝑉 𝑖 = √2𝑔ℎ 𝑉 𝑖 = √2 𝑋 386.4 𝑖𝑛/𝑠𝑒𝑐2 X 18′′ 𝑉 𝑖 = 117.942 𝑖𝑛/𝑠𝑒𝑐 Record V i for an 18” free fall here: 117.942 in/sec Table 1 1. 8” x 8” cushion PE cushion and complete 5 more drops. Collect data for an 18” drop height using a bare platen (12.5 lbs.) on an 8” x 8” cushion Drop #1 Drop #2 Drop #3 Drop #4 Drop #5 43.94 42.59 44.46 42.56 43.45 Table 2 2. 7” x 7” PE cushion and complete 5 more drops. Collect data for an 18” drop height using a bare platen (12.5 lbs.) on a 7” x 7” cushion Drop #1 Drop #2 Drop #3 Drop #4 Drop #5 41.26 42.93 42.53 43.22 43.85 Table 3

LAB G - CUSHION TEST 3. 5” x 5” PE cushion and complete 5 more drops. Collect data for an 18” drop height using a bare platen (12.5 lbs.) on a 5” x 5” cushion Drop #1 Drop #2 Drop #3 Drop #4 Drop #5 32.32 33.12 33.83 35.71 38.09 Table 4 4. 8 ” x 8 ” PE cushion and complete 5 more drops. Collect data for an 18” drop height using a loaded platen (25 lbs.) on an 8” x 8” cushion Drop #1 Drop #2 Drop #3 Drop #4 Drop #5 42.51 42.70 44.27 44.65 44.92 Table 5 5. 6” x 6” PE cushion and complete 5 more drops. Collect data for an 18” drop height using a loaded platen (25 lbs.) on a 6” x 6” cushion Drop #1 Drop #2 Drop #3 Drop #4 Drop #5 31.71 35.87 36.64 37.16 36.96 Table 6 6. 5” x 5” PE cushion and complete 5 more drops. Collect data for an 18” drop height using a loaded platen (25 lbs.) on a 5” x 5” cushion Drop #1 Drop #2 Drop #3 Drop #4 Drop #5 37.49 42.51 43.56 44.45 44.73 Table 7 7. 4” x 4” PE cushion and complete 5 more drops. Collect data for an 18” drop height using a loaded platen (25 lbs.) on a 4” x 4” cushion Drop #1 Drop #2 Drop #3 Drop #4 Drop #5 47.18 52.97 58.25 60.34 60.99 Table 8

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LAB G - CUSHION TEST 2. Calculate the impact velocity expected in a free fall from 24": 𝑉 𝑖 = √2𝑔ℎ Where: V i = impact velocity (in/sec) g = acceleration due to gravity = 386.4 in/sec 2 h = target drop height (inches) = 24 ” 𝑉 𝑖 = √2 𝑋 386.4 𝑖𝑛/𝑠𝑒𝑐2 X 24′′ 𝑉 𝑖 = 136.188 𝑖𝑛/𝑠𝑒𝑐 Record V i for a 24 ” free fall here: 136.188 in/sec Table 9 8. Using a new 8” x 8” cushion sample, perform 5 more drops. Collect data for a 24” drop height using a bare platen (12.5 lbs.) on an 8” x 8” cushion Drop #1 Drop #2 Drop #3 Drop #4 Drop #5 52.61 55.02 57.57 57.14 58.89 Table 10 9. Place the 12.5 lbs. external weight a new 8” x 8” cushion sample, perform 5 more drops. Collect data for a 24” drop height using a loaded platen (25 lbs.) on an 8” x 8” cushion Drop #1 Drop #2 Drop #3 Drop #4 Drop #5 62.43 63.56 60.92 59.61 60.38 Table 11 10. Using the bare platen, perform 5 drops on an ARCEL® cushion. Collect data for a 18” drop height using a bare platen (12.5 lbs.) on an ARCEL® cushion Drop #1 Drop #2 Drop #3 Drop #4 Drop #5 42.97 41.71 43.69 41.08 42.12 Table 12

LAB G - CUSHION TEST CONCLUSION AND APPLICATION In order to protect the contents of the container from shock and damage during transit, cushioning is a crucial component of packaging design, particularly for distribution and transportation. Designing efficient package cushioning systems can be done with the use of cushion curves. When a package material is subjected to various impact situations, such as varying drop heights and weights, these curves reveal information about the deceleration, or rate of change in velocity. Peak G values for various cushioning materials with differing thicknesses under various impact circumstances are measured in order to obtain cushion curves. A cushion curve is produced by graphing these values and depicting how the material responds to various impact scenarios. Based on the anticipated impact conditions and fragility of the shipping goods, packaging designers can choose the best cushioning material and thickness by studying the cushion curves. This might lessen the possibility of product returns or damage claims by ensuring that the product is safeguarded from harm throughout shipping and handling. In conclusion, cushion curves offer useful data for creating efficient cushioning systems in packing, which can help to safeguard the contents of the box during transit and enhance the overall consumer experience.

LAB G - CUSHION TEST LAB G QUESTIONS 1. Describe the cushioning material. Was it closed cell, open cell, plastic, starch, etc.? What were the dimensions L x W and Thickness of the cushion sample(s) tested? The cushioning material is an open cell polymer, they are Polyethylene samples and one ARCEL cushion. The dimensions of the samples are 8’’x 8’’, 7’’x 7’’, 6’’x 6’’, 5’’x 5’”and 4’’x 4’’ with thickness of 2 inches. 2. According to ASTM D1596 what is the recommended minimum sample size? According to ASTM D1596 the recommended minimum sample size is at least three replicate test specimens. 3. Show your calculations for the expected impact velocities for drops from 18" and 24". The impact velocity expected in a free fall from 18": 𝑉 𝑖 = √2𝑔ℎ 𝑉 𝑖 = √2 𝑋 386.4 𝑖𝑛/𝑠𝑒𝑐2 X 18′′ 𝑉 𝑖 = 117.942 𝑖𝑛/𝑠𝑒𝑐 The impact velocity expected in a free fall from 24": 𝑉 𝑖 = √2𝑔ℎ 𝑉 𝑖 = √2 𝑋 386.4 𝑖𝑛/𝑠𝑒𝑐2 X 24′′ 𝑉 𝑖 = 136.188 𝑖𝑛/𝑠𝑒𝑐 4. Determine the "static stress" for each drop in part D. Static stress is the total weight (platen plus add-ons) dropped on the cushion divided by the bearing area (L x W) of the cushion. Show your calculations. No static stress needed for the ARCEL® foam. Static Stress = Total weight / Bearing area Static stress at drop height of 18’’with a load of 12.5 lbs. and 8” x 8” cushion = 12.5 lbs. / 64 in 2 = 0.19 psi

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LAB G - CUSHION TEST Static stress in the following table is calculated in same way Drop Height (inches) Weight (lbs.) Static Stress (psi) 18 ’’ 12.5 0.19 18 ’’ 12.5 0.25 18 ’’ 12.5 0.5 18 ’’ 25 0.39 18 ’’ 25 0.69 18 ’’ 25 1.0 18 ’’ 25 1.56 24 ’’ 12.5 0.19 24 ’’ 25 0.39 5. In ASTM D1596, it is customary to report the "1st impact G" and the "2-5 impact G". The 1st impact G is the peak G you get on the very first drop on a new cushion sample. The 2-5 impact G is the average of the peak G's you got for drops 2-5. This value reflects changes that may have occurred in the cushion from repeated drops. Enter these numbers in a table like the one shown below for all 9 sets of drops in part D (Tables 1 – 9). Do not include the ARCEL® results here. Drop Height (inches) Impact Velocity (in/sec) Static Stress (psi) 1 st impact G (g’s) 2 – 5 impact G (g’s) 18'' 117.9 0.19 43.94 43.27 18'' 117.9 0.25 41.26 43.13 18'' 117.9 0.5 32.32 35.19 18'' 117.9 0.39 42.51 44.14 18'' 117.9 0.69 31.71 36.66 18'' 117.9 1.0 37.49 43.81 18'' 117.9 1.56 47.18 58.14 24" 136.18 0.19 52.61 57.16 24" 136.18 0.39 62.43 61.12

LAB G - CUSHION TEST 6. How does the material you tested compare to expanded polystyrene, whose cushion curves for an 18” drop are shown? To compare, create a cushion curve with the data points you collected. Open the “Lab G – Cushion Curve Creator” Excel file in D2L and fill in the static stress and 1st impact G levels for the 18” impacts only. A graph will be created as you fill in the data. Is it better or worse and what do you base this on? The plot on the left represents the cushion curves of PE foam and the plot on the right represents the cushion curves of EPS foam. The cushion curve of PE foam is for 2’’ thickness. So, if we compare the cushion curve of 2’’ thickness of PE foam to EPS foam, we can observe that the deceleration for 1 psi static stress is higher for PE foam than EPS foam same goes for 1.5 psi static stress too. So, we can assume that PE foam is worse than EPS foam. 7. How do the two 24” drops compare to the two 18” drops of identical static stresses (impacts on 8” x 8” cushions). Fill out the table below with your data. Give a short explanation for these results. 0 20 40 60 80 100 120 0.00 1.00 2.00 3.00 Deceleration, G's Static Stress, psi 18" drop 1st Impact

LAB G - CUSHION TEST Drop Height Weight Static Stress Average G 18” Drop 12.5 lbs. 0.19 43.4 25 lbs. 0.39 43.81 24” Drop 12.5 lbs. 0.19 56.24 25 lbs. 0.39 61.38 Looking at the results we can say that height of an object can affect the rate of deceleration required to bring it to a stop or protect it from impact or shock. Because 24’’ drop height will have higher velocity than 18’’ drop height which requires higher G’s to stop. Similarly, the weight also follows the same pattern as the added weight to the existing platen provides higher velocity because higher weight provides higher momentum to the drop which needs higher G’s. 8. How does the ARCEL® foam handle multiple impacts? Discuss the drop off in performance (increase in shock) after each drop. The performance of ARCEL® foam can be impacted by repeated hits, even though it is a closed-cell foam formed of a mixture of polystyrene and polyethylene theoretically. Each collision can damage the foam to varying degrees, which can limit its ability to absorb stress and raise the amount of shock that is conveyed to the object being protected. The cushioning material's "degradation" or "drop off in performance" are typical names for this occurrence. But looking at the results we found during testing we can see the performance degradation is not consistent. This could be a human error while performing the experiment. Or ARCEL foam does have the capability of staying intact without any performance issues. Drop #1 Drop #2 Drop #3 Drop #4 Drop #5 42.97 41.71 43.69 41.08 42.12

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