Influence Of Interlacement Between Layers On The Cushioning Property Of Corrugated Paperboards

The corrugated paperboard is light-weight,low-cost,easy to be shaped,green and environmentally friendly.In the compressive process,the corrugated paperboard has stable deformation mode,and it can absorb a large amount of energy by deformation so as to mitigate external impact.So,the corrugated paperboard has broad application prospects in the field of transport packaging.The corrugated paperboard is a kind of anisotropic material with higher strength in the direction parallel to the flute direction.On special occasions,the corrugated paperboard needs to resist the compressive loadings in both longitudinal and transverse directions,so the crisscross corrugated paperboard is invented.At present,the research on the interlacement modes and interlacement angles of corrugated paperboard is deficient.Thus,this thesis puts forward two kinds of interlacement modes,interlacement between odd and even layers and interlacement layer by layer,to explore the effect of interlacement angles on the cushioning property of corrugated paperboard.The specimens with interlacement between odd and even layers at a certain angle are C-typed corrugated paperboards.The specimens with corrugated cores interlaced layer by layer are B-typed corrugated paperboards and the adjacent corrugated layers are anticlockwise interlaced with each other at a certain angle.The interlacement angles of specimens with two kinds of interlacement modes are 0°,30°,45°,60° and 90°.The stress-strain curves are obtained by static flatwise and edgewise compressive tests,and the corresponding initial peak stress is obtained.The curves of energy absorption efficiency versus strain are obtained by processing the stress-strain curves,and then the densification strain is determined.Afterwards,the static evaluating indicators of average plateau stress,maximum specific energy absorption and maximum energy absorption per unit volume are calculated to study the effect of two interlacement modes on the cushioning property of corrugated paperboards under flatwise and edgewise directions.For the edgewise direction,the effect of thicknesses and corrugation inclination angles are also studied.In addition,by changing the impact height to get different impact energy and guarantee the same ratio of impact energy to thickness,the effects of two interlacement modes and thicknesses on the dynamic cushioning property of corrugated paperboard in the flatwise direction are studied separately.The contact force-time curves and dynamic evaluating indicators of maximum contact force,maximum displacement and total energy absorption can be obtained by dynamic flatwise compressive testing.And the difference between both the kinetic energy of the hammer before and after the impact is the energy absorption of specimen.The main results and conclusions of the thesis are in the following.1)In the direction of flatwise compression,the influences of interlacement angles on the initial peak stress,average plateau stress,maximum specific energy absorption and maximum energy absorption per unit volume of corrugated paperboards with two interlacement modes are negligible under static flatwise compressions.Under dynamic flatwise impact loadings,the maximum contact force,maximum displacement and total energy absorption of corrugated paperboard increase with the increasing ratios of impact energy to thickness when the thickness of specimen is constant.For a given ratio of impact energy to thickness,the maximum contact force,maximum displacement and total energy absorption of corrugated paperboard increase with the increase of thickness.However,the interlacement angles have little effect on above-mentioned dynamic evaluating indicators for two kinds of interlacement modes.2)In the edgewise direction,thickness of specimens has little effect on the edgewise compressive strength,average plateau stress,maximum specific energy absorption and maximum energy absorption per unit volume.And the static evaluating indicators decrease with the increasing inclination angles of corrugated paperboards.Because nearly half of the corrugated layers are inclined for the corrugated paperboards interlaced between odd and even layers,the above-mentioned static evaluating indicators decrease with the increase of interlacement angles.As the proportion of corrugated layers with the interlacement angle of 90° determines the property of the specimens,the static evaluating indicators first decrease(interlacement angle = 0°~45°),then increase(interlacement angle = 45°~60°),and finally decrease(interlacement angle = 60°~90°)with the increase of the interlacement angles for the corrugated paperboards interlaced layer by layer.