Static Compressive Properties Research Articles

Static-dynamic damage mechanism and self-heating effect of a clean elastic polyurethane grouting material for trenchless rehabilitation under high stresses

Compared with traditional excavation rehabilitation, trenchless grouting rehabilitation technology has the advantages of fast, precise, and low-carbon, which has a broad application prospect in wind turbine foundation rehabilitation. In this work, a non-toxic, environment-friendly, fast-setting, high-strength, and high-toughness elastic polyurethane (PU) grouting material was proposed, and the static-dynamic damage mechanism and self-heating effect under high stress were studied by DMA, SEM, static-dynamic compression, and self-heating monitoring tests. The results show that the static compressive properties increased in a power function relationship with increasing strain rate. The dynamic compression fatigue process can be divided into adjustment stage (Stage I), viscoelastic development stage (Stage II) and failure stage (Stage III) or cyclic hardening stage (Stage III*). At 41.57 MPa and 36.95 MPa, fatigue damage parameters increased slowly in Stage I and Stage II, and sharply in Stage III. The stiffness damage, loss factor, cumulative strain, and strain rate increased by more than 100% in Stage III. Fatigue failure dominated by vertical/slanting through-cracks, shed debris, drum deformation, etc. was closely related to temperature and loading. The failure temperature about 59.1 °C, which was higher than the glass transition temperature. At 32.33 MPa, fatigue damage parameters changed slightly and then stabilized, showing exponential relationships with cycles. The max temperatures were less than 15 °C. The slight temperature rise facilitated the adjustment of structure and cyclic hardening under cyclic loading. This work can guide the further engineering application and fatigue durability evaluation of PU grouting materials.

Static Compressive Properties of Polypropylene Fiber Foam Concrete with Concave Hexagonal Unit Cell

For the purpose of studying the influence of fiber on the negative Poisson’s ratio effect of foam concrete, a concave hexagonal unit cell structure of polypropylene fiber foam concrete was proposed. The effects of different fiber volume contents on the structural mechanical parameters, Poisson’s ratio, and energy absorption capacity of the unit cells were studied by static compression of concave hexagonal unit cells and cube specimens. The results show that the compressive strength of foam concrete is reduced by adding polypropylene fiber, and the peak stress of concave hexagonal unit cells decreases less rapidly than that of cube specimens. The proper amount of polypropylene fiber can enhance the deformation ability of the unit cells in foam concrete, and the Poisson’s ratio of the unit cells in foam concrete with 1.5% fiber content is the lowest. In the process of failure of concave hexagonal unit cells, the failure phenomenon is mainly concentrated on the concave surfaces on both sides, and the cracks are distributed in the form of “upper left and lower right” or “lower left and upper right”. When the content of polypropylene fiber is 0.5%, the total energy absorbed by the concave hexagonal cells in the compression deformation process increases by 12.98%.

Effects of Porosity on the Static Compression of Foam Buffer Materials of Plant Fiber and Their Numerical Model

In recent years, researchers have investigated plant fiber foam buffer package materials for their environmental advantages, which include their ability to completely biodegrade and their rich raw materials. The porosity of buffer materials is an important factor that affects a plant’s static compression property. In this study, foam buffer package materials of plant fiber were developed using bleached bagasse pulp as the main raw material. A digital microscope was used to observe the porosity structures of the foam buffer materials, and the porosity was calculated via binary image processing using Matlab software. The effects of porosity on the static compression properties of cushion materials were discussed, and a numerical model was established. The results indicated that the threshold value chosen affected the calculation of the porosities of buffer materials, which in turn have significant effects on their specific static compression properties. The variation trend of the stress-strain curve fits the hyperbolic tangent function, according to which a numerical model was established. The results of this experiment were in accordance with the theoretical values, which will support the theoretical design of foam buffer package materials of plant fiber.

Synergistic enhancement effect of nano-SiO2 and ionic liquids on mechanical properties and impact resistance of polyurethane elastomer

A nano-polymer (IL@SiO2) was synthesized by double bond polymerization and creatively applied to polyurethane elastomer (PUE-IL@SiO2). The mechanical properties and energy absorption of PUE-IL@SiO2 at static compression and dynamic impact were studied, respectively. The results show that: compared with pure PUE, the static compressive properties and dynamic impact resistance of PUE with a loading of IL@SiO2 of 2wt% are the best, and the static and dynamic compressive yield strength are improved by 216.15% and 190.68% compared with PUE respectively. Moreover, the energy absorption of PUE-2%IL@SiO2 is improved by 18.87% compared with PUE. The composite materials (PUE-2%IL@SiO2) also has excellent deformation recovery performance. These outstanding mechanical properties illustrate the IL@SiO2 is excellent impact resistance and reinforcing materials for PUE.

Static compressive properties and damage constitutive model of rubber cement mortar with dry- and wet-curing conditions

Static compressive properties and damage constitutive model of rubber cement mortar with dry- and wet-curing conditions

Quasi-static compression behaviour of interlocking core structures made of flax fibre reinforced polylactic acid composite

Natural fibres have been gaining a lot of attention for its use in various of fields. It has a potential to replace synthetic fibre due to their availability from renewable natural resources, high specific strength and modulus, low cost, light weight and biodegradability. This paper investigates tensile and quasi static compression properties of flax reinforced polylactide acid (flax/PLA) composites. Initially, the effect of variation of manufacturing temperature on tensile properties of flax PLA composites was examined at three different temperatures of 170, 180 and 190 °C a pressing times of 5, 10 and 15 min were considered. Then a range of double cell walls interlocking square core structures were manufactured using hot press machine and later fabricated through a simple slotting technique. Next, the sandwich structures were tested under quasi-static compression loading with a crosshead displacement rate of 2 mm/min to evaluate their compression properties. The study revealed that that flax/PLA composites manufactured at a temperature of 180℃ and pressed for 5 min. gave the highest value of strength, whereas a temperature of 190℃, pressed for 15 min. is the lowest. Furthermore, results showed that sandwich structures with double cell walls exhibited better strength and energy absorption capacity by approximately 80 and 86% respectively than those offered by ingle cell wall cores as reported in the literatures.

Numerical simulation of static mechanical properties of PMMA microcellular foams

Inspired by recent advancements and owing to their low weight, flexible design, and acceptable cushioning and shock absorption, microcellular foams are being widely utilized in the automotive, helmet, aerospace, and transportation packaging fields. Herein, we research the relationship between the mechanical properties of microcellular foams and their meso-structure. This study combines static mechanical property tests with numerical simulations to analyze and predict the effects of different void porosities, cell sizes, and cell morphologies on the static compressive properties of polymethyl-methacrylate (PMMA) microcellular foams. It was determined that the void porosity of the foam had the most significant influence on the static compression performance. For foams with the same average cell size (7 ± 1 μm), the compressive strength increased by 144% (the void porosity was from 65% to 37%); for foams with the same void porosity (64 ± 1%), the compressive strength increased by 42% (the average cell size was from 21 μm to 8 μm). The cell morphology had the least influence on the static mechanical properties. The ellipsoidal cells had a superior compression performance compared to the spherical and the polyhedral cells; the compressive strength increased by 8.2%.

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

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.

Dynamic and stress relaxation properties of the whole porcine temporomandibular joint disc under compression

In this study, the dynamic and static compressive properties of the whole porcine temporomandibular joint (TMJ) disc were investigated. The aim of the study was to develop a new simple method for the evaluation of joint viscoelasticity, enabling examination of the load-bearing capacity and joint flexibility of the entire disc. For the experiments, a novel testing fixture that reproduces the condylar and fossa surfaces of the TMJ was developed to replicate TMJ disc geometry. Ten porcine discs were used in the experiments. Each disc was dissected from the TMJ and sinusoidal compressive strain was applied to obtain the storage and loss moduli. Static strain control tests were carried out to obtain the relaxation modulus. The result of static and dynamic tests indicated that the whole disc presented viscoelastic behavior under compression. Storage and loss moduli increased with frequency and the relaxation modulus decreased over time. The loss tangent showed less frequency dependence, with values ranging from 0.2 to 0.3, suggesting that the viscous properties of the disc cannot be neglected. These results provide a better understanding of whole disc mechanical compression behavior under realistic TMJ working conditions.

An accurate test method for measuring static compressive properties of a material

In traditional uniaxial compression test, the friction between specimen and bearing plates during testing leads to non-uniform deformation of the specimen. Therefore, the compressive properties of a material may not be accurately measured. To improve the accuracy of measurement, a comprehensive testing scheme is developed in this report. In our method, both close range photogrammetry (CRP) and numerical inversion of the specimen deformation are introduced into a traditional compression test. Firstly, the surface deformation of a specimen during the testing is captured by CRP technique and measured using software Ncorr. Secondly, the mechanical properties of a material can be calculated using testing data. Thirdly, the numerical deformation of specimen under the same loads as those in testing is obtained by finite element method. There is a difference between the testing and numerical results. Minimizing the difference will provide optimal material properties. Finally, an inversion model is built, in which the mechanical properties are design variables. The objective is to minimize the difference between the testing deformation and numerical deformation. The consultant reaction along compression direction on a contact surface of specimen acts as a constraint function. Inversion results show that both the elastic modulus and Poisson’s ratio are modified.

Measurement on Strain Rate Sensitivity Properties of Rice Husk (Rh)/Linear Low Density Polyethylene (Lldpe) Composites under Various Loading Rates

In this study, LLDPE/RH composites were tested under various strain rate loadings (0.001/s, 0.01/s and 0.1/s) using the universal testing machine. Static compression properties of LLDPE/RH composites with different filler contents of 5 wt%, 10 wt%, 15 wt%,20 wt% and, 30 wt% RH were investigated. Results show that the yield stress, ultimate compressive strength and the rigidity properties of LLDPE/RH composites were strongly affected by both filler contents and strain rate loadings. Apart from that, the rate of sensitivity of LLDPE/RH show great dependency towards applied strain rate, where it was increased with increasing strain rates. Unfortunately, the thermal activation values show contrary trend. Visually, from the post damage analysis, the results show that applied strain rates affected the deformation behavior of tested LLDPE/RH composites.

Mechanical Properties of High Density Polyethylene (HDPE)/Sawdust Composites under Wide Range of Strain Rate

An experimental approach based on the conventional universal testing machine (UTM) was employed to perform low strain rate loading (0.001/s, 0.01/s and 0.1/s) in this research, to examine the reliance of natural filler contents towards HDPE/sawdust composites. By following to the low strain rate loading, static compression properties of HDPE/sawdust composites with varies filler contents of 5 wt% SD, 10 wt% SD, 15 wt% SD, 20 wt% SD and 30 wt: % SD were successfully studied. The results show that the yields stress, ultimate compression strength and the rigidity properties of HDPE/sawdust composites were sturdily affected by both filler contents and strain rate loadings. Moreover, for the post damage analysis, the results clearly show that different static loading employed to the specimens gives significant effects towards deformation behavior of HDPE/sawdust composites. The increasing of static loading employed caused the specimens to experience severe deformation.

Dynamic compressive properties of bovine knee layered tissue

In Japan, the most common articular disease is knee osteoarthritis. Among many treatment methodologies, tissue engineering and regenerative medicine have recently received a lot of attention. In this field, cells and scaffolds are important, both ex vivo and in vivo. From the viewpoint of effective treatment, in addition to histological features, the compatibility of mechanical properties is also important. In this study, the dynamic and static compressive properties of bovine articular cartilage-cancellous bone layered tissue were measured using a universal testing machine and a split Hopkinson pressure bar method. The compressive behaviors of bovine articular cartilage-cancellous bone layered tissue were examined. The effects of strain rate on the maximum stress and the slope of stress-strain curves of the bovine articular cartilage-cancellous bone layered tissue were discussed.

OS0705-278 牛の関節軟骨-海綿骨複層組織の圧縮特性に与えるひずみ速度の影響

The tissue engineering and regenerative medicine have received a lot of attention. In this field, cells and scaffolds are important both ex vivo as well as in vivo. From the view point of effective treatment, in addition to histological feature, the compatibility of mechanical properties is also important. In this study, the dynamic and static compressive properties of bovine articular cartilage-cancellous bone layered tissue were measured using a universal testing machine and a split Hopkinson pressure bar method.

The Simulation Research of In-Plane Static Compression Properties of Honeycomb Paperboard Based on FEA

The in-plane mechanical properties of honeycomb paperboard were analyzed and simulated by ANSYS software with finite element analysis method. This paper also explored and optimized finite element modeling method of honeycomb paperboard structure and obtained the equivalent stress distribution maps of honeycomb paperboard in different displacement loads. The mechanical properties and deformation mode of the honeycomb paperboard in the in-plane compression conditions were also analyzed. The results show that longitudinal compressive strength is greater than the lateral compressive strength. The compression deformation mode is different when compressing but appears with the same four stages. The results of finite element analysis have good equivalence with the experimental ones. This paper also revealed the honeycomb paperboard in-plane mechanical properties, deformation and destruction mechanism, further extended the research scope of honeycomb paperboard, and promoted the application of finite element method in the analysis of honeycomb paperboard.

Preparation and Static Cushioning Property of Foaming Packaging Material with Hemp Haulm

Hemp haulm is processing residues extracted after the hemp fiber, with wide raw material sources, cheap price, light quality, good fiber shapes, good toughness, high strength and good buffer performance. In order to develop the application field of hemp stalk processing residues, cushioning packaging materials were prepared using hemp haulm as raw material with the hybrid inorganic foaming agent and corn starch adhesive by microwave foaming method. The properties including density, foam distribution and static compressive properties of this material were analyzed. The experimental results indicated that the density of hemp haulm foaming cushioning packaging materials was 0.235-0.339g/cm3, cell numbers were 14-25.5/cm2, and rebound rate was 62.2%-93.1%. The major influence factors on the properties of hemp haulm foam material were the particle size, foaming agent and adhesives, etc. Research showed while the hemp haulm diameter was small, the ratio of hemp haulm power and starch was 1:0.4 and starch with polyvinyl alcohol (PVA) was 1:0.5, the materials had good buffer performance. When the ratio of compound foaming agent(sodium bicarbonate, ammonium bicarbonate, ammonium carbonate)was 1:2:1, the material had the best cushioning properties as well as higher strength. Compared with polyethylene (EPE) and polystyrene (EPS), the hemp foam material was harder than EPS with no obvious yield point, no material collapsing and good cushioning properties. When the stress was greater than 5-15 N/cm2, the cushioning property of the hemp haulm foaming material was better than EPE, but close to EPS.

Effect of Compression Speed on Static Compression Properties of Foams

Expandable polystyrene and expandable polyethylene foams are frequently used in packaging of products. The study on their cushioning properties is important for the design of the transport package. The effect of compression speed and multiple reloading on the cushioning properties of HDEPS, LDEPS and HDEPE was studied in this paper. The results indicate that the cushioning properties of HDEPS and LDEPS are affected obviously by the compression speed, but the change of the cushioning properties for LDEPE was unconspicuous with the compression speed. LDEPE appeared obvious fatigue after twice reloads.

Microstructural mechanical study of a transverse osteon under compressive loading: The role of fiber reinforcement and explanation of some geometrical and mechanical microscopic properties

This Finite Element study aims at understanding the transverse osteon as a composite microstructure, and at differentiating the actions of each of its main components and their interactions. Three components of the osteon have been distinguished: the lamellae mineral–collagen matrix, the lamellae mineral–collagen reinforcement fibers and the Haversian canal content made of intracortical fluid and soft tissues. Numerical compression experiments have been performed, varying the microstructure properties. Our results show that fiber reinforcement of transverse osteons is only efficient at resisting dynamic compressive loadings, but that the improvement of the static compressive properties is very poor. Furthermore, the modeled stress distribution within the matrix and reinforcement fibers may explain why transverse osteons are often limited to a small number of lamellae (<8) and why internal lamellae could be stiffer than external ones.

The Compressive Properties of Bone Cements Containing Large Doses of Antibiotics

The addition of large amounts of antibiotics to bone cement provides a convenient local delivery, but may influence the compressive properties of the cement. Flucloxacillin and vancomycin were added to Simplex P (Stryker, Limerick, Ireland) and VersaBond (Smith & Nephew) cements. Tripling the antibiotic dose from 2 to 6 g had little effect on the static compressive properties 24 hours after curing. After 4 weeks in phosphate-buffered saline, there was marked decrease in properties with the addition of antibiotics. Compressive strength of cements with 6 g of antibiotic was reduced to near or below the ASTM and ISO minimum of 70 MPa after 4 weeks in phosphate-buffered saline. Microcomputer tomography revealed increased porosity and clumping of the radiopacifier with the addition of antibiotics.

多孔質アルミニウム焼結体の特性に及ぼす原料粒径の影響

In the powder metallurgical process, porous aluminium compacts were prepared by using pure aluminium powders and resin particles as the raw materials. The resin powders classified at more than 250 μm, 110∼250 μm, and less than 110 μm mixed with pure-aluminium powder having average particle size of 20 μm, 10 μm, and 3 μm at the content of 56 vol.%. This mixtures were press-molded into column shape (d=11 mm, L=16∼17 mm). To form pores, resin particles in the green compacts were removed by heat-treatment at 380°C in Ar-gas flow, and then the compacts were sintered at 655°C for 2 hours in vacuum. Effects of particle size of raw materials on the densities and static compressive properties at room temperature for sintered compacts were mainly investigated. The relative densities of sintered compacts were within the range of 39%∼47% on the above-mentioned process conditions. Reduction in particle size of either aluminiun powder or resin particle resulted in higher density. The compressive strength increased with dcreasing the size of aluminium powder. When aluminium powder was 10 μm and 3 μm, the compressive strength increased with decreasing size of resin particle. Especially, the sintered compacts originating in resin particle less than 110 μm had much higher strength than the others regardless of size for aluminium powder.