Experimental study on the compression bearing law

Experimental study on the compression bearing law of triple combined corrugated board (II)

2.1 test method

according to the provisions of method a in gb8168 "experimental method for static compression of cushioning materials for packaging", the static flattening performance of 3b, X-PLY (b) triple combined corrugated board, double corrugated (BB) and single corrugated (b) samples were tested. The pretreatment and test ambient temperature meet the standard requirements, and the loading rate is 12 ± 2.5mm/min. Take the average value of pressure and deformation of each group of test pieces as shown in the figure, and calculate the stress and strain

2.2 test data

2.3 basic law

the horizontal compressive stress-strain curves of the four sizes of samples in Figure 2 show the following law:

a. the quasi linear segment (elastic deformation) of small deformation extends with the increase of the number of corrugated layers. Theoretically, for the determined total compression, the deformation shared by each layer in the multilayer structure is small

b. after the quasi linear segment, the curve develops in a wavy shape, and the number of peaks is consistent with the number of layers. This is due to the difference in material and structure. A layer of corrugated first yields, at this time, the stress drops after crossing the peak, and the strain continues to increase with constant rate loading until the next layer of corrugated failure has a second peak

c. for multilayer plates with the same type of fabric, such as 3b and X-PLY (b), the failure stress of the three layers has little difference, but shows an increasing trend, indicating that on the basis of the same macro strength of each layer, the earlier failure layer still has a certain pressure bearing capacity

d. it is observed in the experiment that the failure always starts from the bottom or top corrugated, and then develops to the adjacent layer. The analysis is: Based on the transverse effect of structural deformation, the pressure bearing specimen has the trend of horizontal expansion when pressed. The friction between the loading surface and the upper and lower surfaces of the sample has the effect of limiting the transverse deformation, making the transverse deformation (elongation) of the paper on and below the corrugation layer out of sync, resulting in the asymmetric deflection of the corrugation, which generally weakens the compressive capacity of the upper and lower layers (as shown in Figure 3). When the boundary layer fails first, the inner paper shared with the adjacent layer has been seriously deformed, damaging the integrity of the adjacent layer, and the subsequent damage is also reasonable

e. the measured results show that the 3b and X-PLY (b) composite plates with different fabric directions, which are both of the same three layers, take 6 fluorine and random supply of lithium phosphate as the breakthrough on the road of transformation and upgrading, have higher compressive capacity (the average failure peak stress of the three layers is 1:1.14). In terms of mechanism, the materials for orthogonal preparation of drug packaging containers should be the coordination and joint bearing advantages of each layer in the deformation process during the bonding of new materials

3 side pressure and side pressure test

(to be continued)