Compressive stress-strain properties of natural materials treated with aqueous NaOH

Holzforschung ◽  
2008 ◽  
Vol 62 (4) ◽  
Author(s):  
Yukiko Ishikura ◽  
Takato Nakano
Keyword(s):  
Compressive Stress ◽  
Energy Absorption ◽  
Shape Change ◽  
Absorption Efficiency ◽  
Threshold Concentration ◽  
Small Range ◽  
Stress Strain ◽  
Longitudinal Contraction ◽  
Energy Absorption Efficiency ◽  
Efficiency Parameter

Abstract Physical and cushioning properties of wood samples treated with various concentrations of NaOH aqueous solutions have been investigated based on compressive stress-strain curves. The shapes of curves changed essentially at NaOH concentrations above 10% as a threshold concentration. The stress-strain curves were analyzed based on the assumption that a rule of mixtures is applicable in the case of a very small range of displacement. The form factor n was also calculated. The values of n of the wood samples treated with NaOH whose concentration was higher than 10% were different from those of the wood samples treated with NaOH whose concentration was less than 10%. The shape changes, longitudinal contraction and twisting of the wood samples are related to NaOH concentration. The energy-absorption efficiency parameter E and ideality parameter I were calculated based on stress-strain curves according to the literature. Also, these parameters change above the threshold concentration of 10%. It was concluded that the cushioning properties of wood treated with alkali concentrations higher than 10% are improved. Due to the shape change of wood samples, the efficiency of energy-absorption properties is higher.

scholarly journals A SHPB Experimental Study on Dynamic Mechanical Property of High-Damping Rubber

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Xiudi Li ◽  
Huaiyuan Mao ◽  
Ke Xu ◽  
Chaoyang Miao
Keyword(s):  
Strain Rate ◽  
Energy Absorption ◽  
Split Hopkinson Pressure Bar ◽  
Dynamic Compression ◽  
Absorption Efficiency ◽  
Stress Strain ◽  
Dynamic Mechanical ◽  
Energy Absorption Efficiency ◽  
High Damping Rubber ◽  
The Ideal

A split Hopkinson pressure bar (SHPB) experiment was done to examine the feasibility and explosion resistance of high-damping rubber materials developed for use in the area of antiexplosion applications. Through the experiment, the dynamic mechanical properties of the high-damping rubber were determined. The existence of dynamic compressive stress-strain curves at various strain rates of the high-damping rubber have been confirmed from the SHPB experiment. The variation law of the dynamic compression performance with the strain rate is studied, and the energy absorption characteristics of high-damping rubber materials are analyzed. To study the microstructural changes of the high-damping rubber before and after impact, a scanning electron microscopy (SEM) test was done. The results indicated that the stress-strain curve and dynamic modulus of high-damping rubber has an obvious strain rate effect, and the strength and energy absorption ability of high-damping rubber material increases with an increase in the strain rate; the ideal energy absorption efficiency of high-damping rubber can reach 0.8 at a high strain rate and the ideal energy absorption efficiency is more than 0.5 in a wide deformation range; when compared with aluminum foam, the energy absorption effect for high-damping rubber is more apparent. In the event of a compressed deformation or the creation of holes, there may be a change in the main internal mechanism of the high buffering and energy absorption capacity of the high-damping rubber.

Research of Compression and Energy Absorption Characteristics of Polyimide Foam

2014 ◽  
Vol 541-542 ◽  
pp. 30-34 ◽  
Author(s):  
Meng Qian Li ◽  
Gang Ma ◽  
Ji Jun Xiao
Keyword(s):  
Energy Absorption ◽  
Compressive Strain ◽  
Testing Machine ◽  
Absorption Efficiency ◽  
Absorption Characteristic ◽  
Stress Strain ◽  
Compression Properties ◽  
Universal Testing ◽  
Energy Absorption Efficiency ◽  
Compaction Stress

The compression and energy absorption characteristic of polyimide foams with three different densities were analyzed in this paper. The compression properties were characterized by CMT7104 Electronic Universal Testing Machine, and the results show that the compressive stress at the same compressive strain increases with the foam density, and the stress-strain curves of polyimide foams with different densities were all composed of elastic region, plateau region and compacted region. The foams ideal energy-absorption efficiency curves were obtained from their stress-strain curves, and all findings show that stress corresponding to at the peak of the energy-absorption efficiency was closed to the compaction stress of material, all their ideal energy-absorption efficiency can reach about 0.8. The polyimide foam is a kind of excellent energy-absorption material.

Compressive Deformation and Energy Absorption Characteristics of Conductive Carbon Black Reinforced Microcellular EPDM Vulcanizates

2005 ◽  
Vol 24 (4) ◽  
pp. 209-222 ◽  
Author(s):  
S.P. Mahapatra ◽  
D.K. Tripathy
Keyword(s):  
Carbon Black ◽  
Compressive Stress ◽  
Energy Absorption ◽  
Filler Loading ◽  
Maximum Efficiency ◽  
Stress Strain ◽  
Blowing Agent ◽  
Compression Set ◽  
Rate Dependent ◽  
Conductive Carbon Black

Compressive stress-strain properties of unfilled and conductive carbon black (VulcanXC 72) filled oil extended EPDM (keltan 7341A) microcellular vulcanizates were studied as a function of blowing agent (density) and filler loading. With decrease in density, the compressive stress-strain curves for microcellular vulcanizates behaved differently from those of solid vulcanizates. The compressive stress-strain properties were found to be strain rate dependent. The log-log plots of relative density of the microcellular vulcanizates showed a fairly linear correlation with the relative modulus. The compression set at a constant stress increased with decrease in density. The efficiency of energy absorption E, was also studied as a function of filler and blowing agent loading. From the compressive stress-strain plots the efficiency E and the ideality parameter I, were evaluated. These parameters were plotted against stress to obtain maximum efficiency and the maximum ideality region, which will make these materials suitable for cushioning and packaging applications in electronic devices.

Energy Absorption of Origami Crash Box: Numerical Simulation and Theoretical Analysis

2018 ◽  
Author(s):  
Mengyan Shi ◽  
Jiayao Ma ◽  
Yan Chen ◽  
Zhong You
Keyword(s):  
Energy Absorption ◽  
Theoretical Study ◽  
Low Cost ◽  
Deformation Mode ◽  
Absorption Efficiency ◽  
Great Promise ◽  
Good Match ◽  
Energy Absorption Efficiency ◽  
Thin Walled ◽  
Initial Peak

Thin-walled tubes as energy absorption devices are widely in use for their low cost and high manufacturability. Employing origami technique on a tube enables induction of a predetermined failure mode so as to improve its energy absorption efficiency. Here we study the energy absorption of a hexagonal tubular device named the origami crash box numerically and theoretically. Numerical simulations of the quasi-static axial crushing show that the pattern triggers a diamond-shaped mode, leading to a substantial increase in energy absorption and reduction in initial peak force. The effects of geometric parameters on the performance of the origami crash box are also investigated through a parametric study. Furthermore, a theoretical study on the deformation mode and energy absorption of the origami crash box is carried out, and a good match with numerical results is obtained. The origami crash box shows great promise in the design of energy absorption devices.

Bending Behavior of Simply-Supported Sandwich Beams Subjected to Large Deflection

2018 ◽  
Vol 777 ◽  
pp. 569-574
Author(s):  
Zhong You Xie
Keyword(s):  
Energy Absorption ◽  
Large Deflection ◽  
Absorption Efficiency ◽  
Sandwich Beams ◽  
Element Simulation ◽  
Energy Absorption Efficiency ◽  
Load Carrying ◽  
Absorption Performance ◽  
Bending Behavior ◽  
The Moment

Due to thin skins and soft core, it is apt to local indentation inducing the concurrence of geometrical and material nonlinearity in sandwich structures. In the paper, finite element simulation is used to investigate the bending behavior of lightweight sandwich beams under large deflection. A modified formulation for the moment at mid-span section of sandwich beams under large deflection is presented, and energy absorption performance is assessed based on energy absorption efficiency. In addition, it is found that no local indentation arises initially, while later that increases gradually with loading displacement increasing. The height of the mid-span section as well as load-carrying capacity decreases significantly with local indentation depth increasing.

Compressive Properties of Electroless Ni-P Coating Reinforced Magnesium Alloy Foams

2021 ◽  
Vol 889 ◽  
pp. 123-128
Author(s):  
Sheng Jun Liu ◽  
Zhi Qiang Dong ◽  
Ren Zhong Cao ◽  
Da Song ◽  
Jia An Liu ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Energy Absorption ◽  
Absorption Efficiency ◽  
Absorption Capacity ◽  
Compressive Properties ◽  
Compressive Test ◽  
Energy Absorption Capacity ◽  
Energy Absorption Efficiency ◽  
Hybrid Foams ◽  
Electroless Ni

In this study, the open-cell Mg-2Zn-0.4Y foams were prepared by infiltration casting method. The Ni/Mg hybrid foams were prepared by electroless Ni-P coating on the foam struts to improve the compressive strength and energy absorption capacity. The compressive properties of the Mg alloy foams and Ni/Mg hybrid foams were studied by quasi-static compressive test. The experimental results show that the Ni-P coating is composed of crystallites. The Ni-P coating can significantly enhance the compressive strength, energy absorption capacity and energy absorption efficiency of the foams.

scholarly journals Energy Absorption of Different Cell Structures for Closed-Cell Foam-Filled Tubes Subject to Uniaxial Compression

Metals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1579 ◽  
Author(s):  
Yang Yu ◽  
Zhuokun Cao ◽  
Ganfeng Tu ◽  
Yongliang Mu
Keyword(s):  
Energy Absorption ◽  
Absorption Efficiency ◽  
Foam Core ◽  
Aluminum Foams ◽  
Static Compression ◽  
Cell Structures ◽  
Closed Cell ◽  
Energy Absorption Efficiency ◽  
Foam Filled ◽  
Quasi Static Compression

The energy absorption of different cell structures for closed-cell aluminum foam-filled Al tubes are investigated through quasi-static compression testing. Aluminum foams are fabricated under different pressures, obtaining aluminum foams with different cell sizes. It is found that the deformation of the foam core is close to the overall deformation, and the deformation band is seriously expanded when the cell size is fined, which leads to the increase of interaction. Results confirm that the foam-filled tubes absorb more energy due to the increase of interaction between the foam core and tube wall when the foaming pressure increases. The energy absorption efficiency of foam-filled tubes can reach a maximum value of 90% when the foam core is fabricated under 0.30 MPa, which demonstrates that aluminum foams fabricated under increased pressure give a new way for the applications of foam-filled tubes in the automotive industry.

Crash Analysis of UAV Hybrid Composite Fuselage Structure under Different Impact Conditions

2019 ◽  
Vol 953 ◽  
pp. 88-94
Author(s):  
Mohamed Zahran ◽  
Mostafa Abdelwahab
Keyword(s):  
Energy Absorption ◽  
Hybrid Composite ◽  
Absorption Efficiency ◽  
Crash Analysis ◽  
Critical System ◽  
Maximum Acceleration ◽  
Finite Element Software ◽  
Energy Absorption Efficiency ◽  
Hybrid Composite Material ◽  
Technological Developments

Due to the rapid scientific and technological developments in the aerospace industry, the requirement for safety and energy absorption efficiency is increasing, and in order to achieve that target, the analyzing of the sudden crash is required to know how to reduce it. Therefore, the main objective of the present work is to analyze the crashing response of the hybrid composite fuselage structure during different impact landing conditions. Moreover, extract the maximum acceleration at the most important locations in the UAV fuselage where most of the critical system is installed. The explicit non-linear finite element software LS-DYNA/WORKBENCH ANSYS is chosen to simulate the crushing of the referenced and the proposed UAV fuselage and investigate the maximum crushing accelerations responses on the payload under different landing conditions. The numerical results show that strengthen the fuselage structure using hybrid composite material has a notable effect on the energy absorption, and transferred acceleration on the payload. Moreover, the hybrid composite fuselage structure can reduce the transferred acceleration on the payload up to 39.65% in comparison with the metal fuselage. In addition, to study the crash analysis during sudden accidents is very important, in order to find the way to reduce it, but can’t avoid it. Hence, the UAV payload should be arranged to avoid the maximum acceleration.

Cushioning energy absorption of composite layered structures including paper corrugation, paper honeycomb and expandable polyethylene

2019 ◽  
Vol 54 (3) ◽  
pp. 176-191 ◽  
Author(s):  
Yanfeng Guo ◽  
Meijuan Ji ◽  
Yungang Fu ◽  
Dan Pan ◽  
Xingning Wang ◽  
...  
Keyword(s):  
Energy Absorption ◽  
Specific Energy ◽  
Peak Stress ◽  
Layered Structures ◽  
Absorption Efficiency ◽  
Compression Stress ◽  
Static Compression ◽  
Specific Energy Absorption ◽  
Energy Absorption Efficiency ◽  
Paper Honeycomb

The composite layered structures including paper corrugation, paper honeycomb and expandable polyethylene are innovative structures of cushioning energy absorption, and the compression and impact resistances of the expandable polyethylene can be enhanced by laminating the corrugated paperboard or honeycomb paperboard. This article evaluated the compression performance and cushioning energy absorption of the composite layered structures by the static compression and drop impact compression tests. On one hand, the static compression properties showed that the total energy absorption, energy absorption per unit volume and stroke efficiency of the composite layered structures were all higher than those of expandable polyethylene. The specific energy absorption was enhanced with the increase in compression strain but almost not affected by the compression rate. The specific energy absorption of the composite layered structures including the expandable polyethylene and honeycomb paperboard was greater than those of the expandable polyethylene and corrugated paperboard. The energy absorption efficiency of the composite layered structures including the expandable polyethylene and corrugated paperboard was large for the low compression stress level, yet that of the composite layered structures including the expandable polyethylene and honeycomb paperboard was large for the high compression stress level. On the other hand, the dynamic compression characteristics showed that the peak stress, energy absorption per unit area, energy absorption per unit volume and specific energy absorption of the composite layered structures embodying paper sandwich cores and expandable polyethylene had linear increasing trends with the increase of drop shock energy. At the same drop impact condition, the composite layered structures including the honeycomb paperboard and expandable polyethylene had better cushioning energy absorption, the peak stress decreased by 23.6% on average, the energy absorption efficiency raised by 8.85% on average and the specific energy absorption increased by 18.1% on average than those including the corrugated paperboard and expandable polyethylene. Therefore, the corrugated paperboard and honeycomb paperboard can helpfully improve the cushioning energy absorption of the expandable polyethylene, and the composite layered structures embodying the expandable polyethylene, corrugated paperboard and honeycomb paperboard may hold excellent packaging protection.

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