Static Tensile Strength Research Articles

Biological oyster shell waste enhances polyphenylene sulfide composites and endows them with antibacterial properties

To date, there is no research that deals with biological waste as fillers in polyphenylene sulfide (PPS). In this study, oyster shells were recycled and treated to prepare thermally-treated oyster shells (TOS), which were used as PPS fillers to make new bio-based antibacterial composite materials. The effect of varying the content of TOS was studied by means of structure and performance characterization. PPS/TOS composites were demonstrated to have an antibacterial effect on the growth of E coli and S. aureus. Qualitative analysis showed that when the TOS content was ≥ 30% and 40%, the composite materials had an apparent inhibition zone. Quantitative analysis showed that the antibacterial activity increased with the TOS content. Fourier transform infrared spectroscopy indicated the formation of hydrogen bonds between the molecular chains of TOS and PPS and the occurrence of a coordination reaction. At 10% TOS, the composite tensile strength reached a maximum value of 72.5 MPa, which is 9.65% higher than that of pure PPS. The trend of bending properties is the same as that of tensile properties, showing that the maximum property was reached for the composite with 10% TOS. At the same time, the crystallinity and contact angle were the highest, and the permeability coefficient was the lowest. The fatigue test results indicated that for the composite with 10% TOS, the tensile strength was 23% lower than static tensile strength, and the yield strength was 10% lower than the static yield strength. The results of the study showed that TOS not only could reduce the cost of PPS, but also could impart antibacterial properties and enhance the mechanical and, barrier properties, the thermostability, as well as the crystallinity.

Direct energy deposition of Cu–Nb functionally graded layers for dissimilar joining titanium alloys and steels

The heterogeneous compounds of titanium and iron steel are of wide interest in additive manufacturing. To prevent the formation of brittle intermetallic compounds, a layer of Nb and Cu was used. The use of the Nb and Cu interlayer successfully prevents the mixing of Ti and Fe, thus avoiding the formation of FexTiy brittle phases. In the Ti–Nb–(Nb + Cu–10Al) transition interlayer, it was possible to achieve the interlayer without the formation of brittle phases. The static tensile strength of the Grade1/316 L compounds with Nb–(Nb + Cu–10Al) interlayer is 335.5 MPa, the compounds exhibit ductile–brittle fracture.

Evaluation of fatigue strength of carbon fiber reinforced plastics (CFRP) with various types of hybrid matrices

Polymer composite materials (PCM) have found wide application in various industries due to the ability to create low-weight products with specified operational properties. During operation, composite products are exposed to static and cyclic loads, climatic and many other factors. Evaluation of the fatigue strength of composite materials and the influence of various additives and modifiers on it is an urgent scientific and practical task. The article describes the technology of obtaining PCM with various types of hybrid matrices formed by the main binder material and the material representing an independent "liquid" phase in the composite structure. Based on the analysis of the kinetics of curing, anaerobic polymer material (Loctite 638), silicone elastomer (Unisil-9628) and synthetic wax were selected as the materials of the components of the "liquid" phase. Fatigue strength assessment tests were carried out by applying cyclically varying tension-compression loads to the samples. The load during cyclic tests was 70% of the static tensile strength of the samples. The residual strength was evaluated by testing the tensile strength of the samples until complete destruction after cyclic loading. The results of fatigue strength tests of carbon fiber plastics with various types of hybrid matrices (formed by various components of the "liquid" phase) are presented. The analysis of the results showed that the use of an anaerobic polymer material as a component of the "liquid" phase of the hybrid matrix makes it possible to increase both the initial static strength of the material (by ~ 1%) and the residual strength after cyclic loading (by ~ 11%) compared with these indicators obtained during the testing of control samples. After performing cyclic loading, carbon fiber plastics with anaerobic polymer material and silicone elastomer have an increase in residual strength compared to previously performed static tensile tests by ~ 8% and ~13%, respectively. The use of an anaerobic polymer material and silicone elastomer as a component of the "liquid" phase makes it possible to increase the modulus of elasticity of carbon fiber plastics after cyclic loading by ~ 13% and 5%, respectively, compared with the results of preliminary static tests.

Preparation and characterization of flexible laminated composites impregnated with TPU/SiO2 for static puncture resistance

At present, people face the danger of various occupational exposures, resulting in the rapid development of protective composites among which puncture-resistant materials are an essential component. In this article, composites impregnated with polyester polyurethane (TPU)/SiO2 are used to improve static puncture resistance. Different types of TPU and different concentrations of SiO2 in the impregnation solution are selected. The mechanical and wearing-related properties of composites are systematically explored and analyzed. The results show that static puncture resistance and tensile strength are improved after impregnation. Meanwhile, the composites can still maintain a good water-vapor transmission rate. The air permeability, tearing strength, elongation at break and flexibility of the composites decrease slightly. This study provides a novel and feasible strategy to prepare a flexible composite with high static puncture resistance as well as excellent wearability which is a desirable candidate as a garment accessory or gaket protecting the human body from puncture risk.

Experimental and mesoscopic investigation of self-compacting rubberized concrete under dynamic splitting tension

Self-compacting rubberized concrete (SCRC) has gained extensive investigations due to its good impact resistance and environmental friendliness, while the dynamic splitting tensile properties of SCRC are seldom studied. In this study, river sand in SCRC was replaced by three rubber volume fractions (5%, 10%, 15%). The experiments indicated that the static compressive strength, static tensile strength, elastic modulus and dynamic splitting tensile strength declined with the increase of rubber content. The dynamic splitting tensile strength, dynamic increase factor (DIF) and failure mode of SCRC were sensitive to strain rate. SCRC with a higher rubber volume had a greater DIF. The critical strain rate of different SCRC was obtained by piecewise fitting, which decreased with the enhancement of rubber content. Meanwhile, a three-dimensional mesoscopic model of SCRC was established. The rubber particles were generated by a random polyhedron algorithm and randomly thrown into the sample by the take and place algorithm. The numerical calculation suggested that the mesoscopic model could exhibit the fracture process of SCRC under high strain rates. The propagation of cracks bypassed the rubber particles and produced a mass of branch cracks under high strain rates, dissipating a large amount of energy and elevating the DIF, which is consistent with the macroscopic failure pattern. In addition, the effect of strain rate and rubber volume on DIF was discussed combined with the mesoscopic model.

Lithological controls on fault damage zone development by coseismic tensile loading

During subshear earthquake rupture opposing sides of the fault experience transient impulses of tensile and compressive peak mean normal stresses exceeding the strength of the rock resulting in off-fault damage. This damage is expected to be influenced by lithology and occur preferably on the nominally tensile side of ruptures because rocks are weaker in tension than compression. Whereas the static tensile strength of many rocks is known, our capacity to relate parameters used to quantify brittle deformation in fault damage zones commonly measured in the field, including fracture density and fragment size, to earthquake rupture conditions is poor. This is due to a lack of experimental data relating tensile strength, fracture density, and fragment size to lithology under transient loading conditions. To relate brittle damage to coseismic tensile loading conditions, we use a modified sample configuration for a Split Hopkinson Pressure Bar (SHPB) designed to induce tensile rock fragmentation. Experiments cover a range of rock types including granite, diabase, welded tuff, and sandstone. All crystalline rocks fail predominantly via mode-I fracture, while sandstone fails through localized dilation bands, distributed pore space expansion, and less common mode-I fractures. Measurements of fracture density, fragment size, and porosity change are compared to tensile strength and strain rate at failure. We derive empirical relationships for (1) the transition from fracture to dilation banding as a function of initial porosity and (2) the strain rate dependence of tensile strength. These empirical relationships are used to estimate the rock strength during earthquake rupture on the side of the fault loaded under tension for comparison to predicted stress decay with distance from a fault to estimate the lithology dependent extent and nature of coseismic fault damage. Our experiments offer new insights into the lithological controls on the formation of asymmetric fault damage zones by dynamic rupture.

Effect of steel fiber type and content on the dynamic tensile properties of ultra-high performance cementitious composites (UHPCC)

As one of the most promising construction and building materials in the past 30 years, ultra-high performance concrete (UHPC) has attracted a great deal of attention and the studies on its improvement and dynamic tensile behaviors become more important for its wider use in the related fields. In this contribution, a novel ultra-high performance cementitious composites (UHPCC) was developed with lower cement content, 20% of cement is replaced with fly ash and blast furnace slag, to reduce the raw material cost and carbon emission in production. Uniaxial compression, quasi-static and dynamic splitting tests were carried out to investigate the influences of steel fiber type (straight fiber and waved fiber) and content (volume fraction (0%, 1%, 2%)) on the uniaxial compressive strength, static tensile strength and dynamic tensile behaviors for current UHPCC material. The dynamic splitting tests were conducted on 100 disc specimens (75 mm in diameter and 37.5 mm in thickness) under five different impact pressure at a strain-rate range of 20–110 s−1 to study the strain rate effect by using a Split Hopkinson pressure bar (SHPB) system and the samples’ failure processes were captured by a high-speed camera. Based on the test results, the variations of energy absorption with the fiber type and content under static and dynamic tensile conditions are also analyzed, and combined with the experimental data from previous studies, an improved empirical tensile strength rate sensitivity (DIFft) model is proposed, which agrees well with the experiment results and can be used in the numerical simulation. At last, the failure process and pattern of different types of UHPCCs in the dynamic splitting test are also studied.

Failure mechanism of unidirectional basalt fiber‐reinforced polymer composites with pretension of fiber yarns

AbstractThe pultrusion process has received increasing attention because of its high productivity, low cost, and good product quality. During the pultrusion process, the pulling and pretension force is a key factor to control the quality of the products. In this paper, the effect of the pretension force on the tensile strength of basalt fiber‐reinforced polymer (BFRP) composites was studied. The pretension force was controlled using different weights. Tensile tests were performed on the BFRP specimens and the microscopic analysis was examined by scanning electron microscopy. The results showed that the static tensile strength of specimens climbed up initially, followed by a decrease with the increase of pretension weights. Three microscopic changes under different pretension forces were found and discussed to explain the damage and failure mechanism. It is essential to optimize the pretension force to improve the strength quality for the pultrusion products of BFRP.

Polymer Composites Based on Glycol-Modified Poly(Ethylene Terephthalate) Applied to Additive Manufacturing Using Melted and Extruded Manufacturing Technology.

As part of the work, innovative polymer composites dedicated to 3D printing applications were developed. For this purpose, the influence of modified fillers, such as silica modified with alumina, bentonite modified with quaternary ammonium salt, and hybrid filler lignin/silicon dioxide, on the functional properties of composites based on glycol-modified poly(ethylene terephthalate) (PET-G) was investigated. In the first part of the work, using the proprietary technological line, filaments from unfilled polymer and its composites were obtained, which contained modified fillers in an amount from 1.5% to 3.0% by weight. The fittings for the testing of functional properties were obtained using the 3D printing technique in the Melted and Extruded Manufacturing (MEM) technology and the injection molding technique. In a later part of the work, rheological properties such as mass melt flow rate (MFR) and viscosity, and mechanical properties such as Rockwell hardness, Charpy impact strength, and static tensile strength with Young’s modulus were presented. The structure of the obtained composites was also described and determined using scanning electron microscopy with an attachment for the microanalysis of chemical composition (SEM/EDS) and the atomic force microscope (AFM). The correct dispersion of the fillers in the polymer matrix was confirmed by wide-angle X-ray scattering analysis (WAXS). In turn, the physicochemical properties were presented on the basis of the research results: thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and Fourier transform infrared spectroscopy (FT-IR). On the basis of the obtained results, it was found that both the amount and the type of fillers used significantly affected the functional properties of the tested composites.

Experimental investigation on the effect of open fire on the tensile properties and damage evolution behavior of granite

The stability of rock mass after fire is a concern of many engineering projects. In this paper, the effects of open fire and different cooling methods on granites were investigated. The static Brazilian test, dynamic Brazilian test, and P-wave velocity test were carried out to evaluate the mechanical properties and damage evolution behavior. A high-speed camera is employed to monitor the failure process of rock. The microstructures of the treated granites were observed by scanning electron microscope (SEM). The results showed that the fire duration and cooling treatment have a significant effect on the P-wave velocity, static nominal tensile strength, and dynamic nominal tensile strength of granite. These characteristics decrease rapidly during 0 to 10 min, and slowly decrease after 20 min. Compared to the air-cooling treatment, the water-cooling treatment has greater damage to the heated granite. To better understand the results, the rapid heating process of open fire heating was simulated using Abaqus software. The results reveal that there is a thinner compressive stress zone at the bottom of the specimen, and there is a large zone in the middle of the sample with higher tensile stress. The crack extension would be expanded due to high tensile stress, leading to the reduction of the tensile strength of the rock. This paper aims to better predict the degree of damage of rock materials after actual fire, as well as preliminarily explore the effect of the fire exposure duration and fire extinguishing method on the tensile properties of rock.

Effects of Compaction Efforts on Tensile Strength Characteristics And Durability of Warm-asphalt Mixture Containing Natural And Synthetic Zeolite

Many studies have been conducted to evaluate the mechanical properties of warm-mix asphalt (WMA) mixtures using Natural Zeolite (NZ) and Synthetic Zeolite (SZ) without considering the impact of compaction efforts. In this study, the influence of compaction cycles on the mechanical characteristics of WMA mixtures including NZ & SZ additives, is studied and compared with hot mix asphalt (HMA) mixtures. The amount of NZ and SZ used to make the WMA mixes was 5% of the whole asphalt mass. For the research, six WMA mixtures with a penetration grade of 40-50 were designed and compared to HMA traditional mixture. HMA &WMA mixtures were designed with 35, 50 and 75 compaction efforts. Mechanical and durability experiments were performed on HMA and WMA mixtures, involving Marshall stability, Marshall quotient, static indirect tensile strength at 25 and 60°C, and tensile stiffness modulus at 25 and 60°C. Calculating the tensile strength ratio (TSR) to study the moisture susceptibility of the mixes was used to assess their durability. The study indicates that compaction efforts had a considerable impact on the performance of the mixtures. The Natural Zeolite of WMA & Synthetic Zeolite of WMA mixtures display lower Marshall stability and Marshall quotient with greater tensile strength and tensile strength ratio than HMA mixture for 35, 50 and 75 compaction efforts. Increased compaction efforts result in a greater reduction in mechanical and durability characteristics of WMA. The flow values of NZWMA and SZWMA mixtures are larger than HMA mixtures indicating higher strain capacities to achieve failure. All NZWMA and SZWMA mixtures achieve the SCRB standard specifications of 8kN stability, 2-4mm flow, 14 percent VMA, and 85 percent TSR when using the same optimum binder content. Furthermore, the NZAC mixtures show higher performance than SZAC mixtures in terms of stability and strength

Experimental investigation on the dynamic tensile characteristics of conglomerate based on 3D SHPB system

The mechanical properties and failure characteristics of conglomerate, main components of gravel layer, are of great significance to the study of efficient drilling methods in gravel layer. However, there are few works published previously, especially rare in terms of dynamics. While drilling in gravel layer, the bottom hole rock is subjected to complex loads, including impact loading and in-situ stress. The static and dynamic tension behaviours of conglomerate are tested by outcrop in this paper. Based on GCTS and 3D SHPB systems respectively, the static and dynamic tensile properties are analyzed, and the energy consumption while failure and the influence of axial static load on dynamic tensile characteristics are discussed. Results show that the tensile characteristics of conglomerate have a significant strain rate correlation, and the dynamic tensile strength is significantly higher than that of static; The strength in both impact direction and axial direction increase linearly with the loading strain rate, while the failure strain decreases linearly; As there is no axial load and the strain rate is 140.31–248.95 s−1, the dynamic tensile strength is 75.86–109.91 MPa, and the strength growth factor is 10.55–15.29 between the dynamic and static tensile strength. Due to the energy absorbed by the specimen increases exponentially in the dynamic test, there are a great number of cracks produced accompanied by the collapse of large debris, manifested as the volume crushing failure mainly, while in the static test, there is mainly brittle splitting failure. The dynamic tensile strength can be reduced linearly by increasing the axial static load or reducing the dynamic load. The research has an important theoretical reference for the study of drilling technology and theory in the gravel-rich stratum.

Loading Mode and Lateral Confinement Dependent Dynamic Fracture of a Glass Ceramic Macor

AbstractA systematic comparison of the tensile and compressive response of glass ceramic Macor, with zero porosity and low density, is carried out by using flattened Brazilian disk and cylindrical specimen from quasi-static to dynamic loading conditions. The experiments were performed on a screw driven Zwick machine and an in-house built split Hopkinson bar synchronized with a high speed photographic system. Likewise, the loading rate dependent fracture toughness is also investigated by using a notched semi-circular Brazilian disk. A digital image correlation technique is adopted to assist in the monitoring of strain field, crack initiation and propagation under dynamic loading conditions. Both tensile and compressive strength show loading rate dependencies, however, the static and dynamic tensile strengths are only 20% of the compressive strengths without confinement and less than 10% of the confined compressive strength. The microstructural characterization reveals the fracture mechanisms in unconfined Macor are predominantly transgranular with mica platelets and cleavage planes, which are influenced by the loading mode and loading rate. However, the Macor with confinement shows ductile fracture micrographs with a shear localization zone consisting of fine particles. With the use of Macor ceramic as a model material, the paper presents an economical approach to investigate the loading mode and pressure dependent failure of ceramic materials. This will support the characterization of dynamic properties of current and future developed advanced ceramics for demanding applications in the aero engine.

Evaluation of the Fatigue Strength of a CAD-CAM Nanoceramic Resin Crown on Titanium and Zirconia-Titanium Abutments

A computer-aided design/computer-aided manufacturing (CAD/CAM) resin block material for restoration of single-implant abutments can be milled and cemented on an optimized standard titanium abutment as a cheaper solution or, alternatively, individualization of the crown–abutment connection is required to fulfill the same mechanical requirements. The aim of this study was to evaluate how different structural and geometric configurations of the abutment influence the resistance of a nano ceramic resin crown (NCRC). During the test, 30 implants with an internal conical tapered configuration were considered. Each implant received a standard titanium abutment: in group 1, NCRCs were directly bonded to the titanium abutments; in group 2, NCRCs were cemented on a customized zirconia framework and then cemented on a standardized titanium abutment. Three crowns of each group were submitted to a static load test until failure. The remaining crowns were submitted to a fatigue test protocol with a dynamic load. The static and dynamic test showed earlier failure for group 1. In group 1, complete breaking of NCRCs was observed for all samples, with an almost total titanium abutment exposition. In the static tests, group 2 showed a mode of failure that involved only the crown, which partially debonded from the zirconia abutment. Within the limitations of the present preliminary study, it was possible to conclude that the shape of the abutment mainly influences the fatigue strength compared to the static tensile strength. The results of the performed test show that NCRC bonded to the customized zirconia abutments, and presented a 75% survival rate when compared to the same material bonded directly to a standard titanium abutment.

ВЛИЯНИЕ КРУПНОГО ЗАПОЛНИТЕЛЯ НА ЭНЕРГЕТИЧЕСКИЕ И СИЛОВЫЕ ХАРАКТЕРИСТИКИ СТАЛЕФИБРОБЕТОНА

At present, composite materials are gaining more and more development in construction, including the use of dispersed reinforced concrete, which is due to its significantly improved physical, mechanical and operational characteristics compared to traditional concrete and reinforced concrete. The article presents the results of the influence of coarse filler in the composition of the composite on the energy and power characteristics of the crack resistance of fiber-reinforced concrete reinforced with steel anchor fibers. The process of deformation and the mechanism of destruction of steel fiber reinforced concrete have been studied. To do this, in accordance with the provisions of GOST 29167 "Methods for determining the characteristics of crack resistance (fracture toughness) under static loading", steel-fiber-reinforced concrete sample beams were tested with control of the applied load and the deflection caused by it. Based on the data obtained, diagrams of the dependence of the load on the deflection were constructed, after their processing and additional constructions, the energy costs for static destruction, tensile strength in bending, and the stress intensity factor were determined. It has been established that the value of the conditional specific effective energy consumption for static failure and tensile strength in bending of fiber-reinforced concrete samples with a matrix of heavy concrete with coarse aggregate turned out to be lower than that of fiber-reinforced concrete samples with a matrix of fine-grained concrete, which is explained by the lower adhesion of the steel anchor fiber to the matrix, and a corresponding decrease in their efficiency.

Influence of damages (hole/slits) on tensile behavior of Al 7075-T6/glass fibre-based hybrid laminates

The metal alloy and polymer composite-based hybrid laminates (fibre metal laminates) have significant importance over other materials used in aircraft, automobile industry and in other structural applications due to their low density, better mechanical properties, good corrosion and wear resistance etc. But these laminates are easily susceptible to damages in working environment. So, in the present study, the tensile strength experiment is conducted on two glass fibre laminated aluminum alloy (Al 7075-T6) specimens in undamaged and damaged conditions to understand the impact of damages on tensile behavior of these hybrid laminates. 9.03%, 27.8%, 40.36% of reduction in tensile strength was observed by incorporation of 10 mm hole, 1 mm slit, 2.5 mm slit damages respectively. It is observed from the results that 2.5 mm cut is highly influencing the tensile behavior of fibre metal laminate compared to other damages due to its rapid crack propagation through the specimen. For hole damaged laminates, there may be reduction in the static tensile strength due to the absence of stress relaxation through the damage, which leads to high stress concentration around this damage and brittle failure, consequently.

Structure and Mechanical Properties of Shipbuilding Steel Obtained by Direct Laser Deposition and Cold Rolling.

The study of the formation of microstructural features of low-alloy bainite-martensitic steel 09CrNi2MoCu are of particular interest in additive technologies. In this paper, we present a study of cold-rolled samples after direct laser deposition (DLD). We investigated deposited samples after cold plastic deformation with different degrees of deformation compression (50, 60 and 70%) of samples from steel 09CrNi2MoCu. The microstructure and mechanical properties of samples in the initial state and after heat treatment (HT) were analyzed and compared with the samples obtained after cold rolling. The effect on static tensile strength and impact toughness at −40 °C in the initial state and after cold rolling was investigated. The mechanical properties and characteristics of fracture in different directions were determined. Optimal modes and the degree of cold rolling deformation compression required to obtain balanced mechanical properties of samples obtained by additive method were determined. The influence of structural components and martensitic-austenitic phase on the microhardness and mechanical properties of the obtained samples was determined.

The influence of knot types on rope static tensile strength

The choice of material, type of braid and rope parameters are a broad issue of great importance in the designing process. An equally important issue is the proper selection of knot type used for attaching the rope to the other elements of a structure, as this is a critical point accumulating major stresses. Inappropriate tying of a rope may decrease its tensile strength by over 50%; therefore, it is an important issue in terms of structural strength. This article investigates different tying configurations of the same rope and shows the influence of knot types on rope static tensile strength.

Recyclability of new polylactide based biodegradable materials with plant extracts containing natural polyphenols

The paper presents the results of research on multiple processing of a polylactide-based polymer material containing natural anti-aging compounds. The aim of the research was to determine the effectiveness of coffee, cocoa and cinnamon extracts in limiting the adverse effects that occur during multiple mechanical recycling of polylactide. The melt flow rate, static tensile strength, impact strength, thermogravimetry, differential scanning calorimetry and thermomechanical tests were conducted. It was found that despite repeated processing, the materials containing the extracts had properties enabling proper processing and every day applications. The obtained results were often better than the results obtained for the material containing the synthetic anti-aging compound.

Study on Properties of Energetic Plasticizer Modified Double‐Base Propellant

AbstractTo improve the low‐temperature mechanical properties of double‐base propellants, the effects of three energetic plasticizers (geminal dinitro aldehyde acetal plasticizer, azido‐terminated glycidyl azide polymer, and ester‐terminated glycidyl azide polymer) on the low‐temperature mechanical properties of nitrocellulose (NC)/nitroglycerin (NG) propellant were studied firstly in this article. It was found that azido‐terminated glycidyl azide polymer (GAPA) was the most effective plasticizer to improve the low‐temperature mechanical properties of NC/NG propellant. Then the effects of GAPA on the low‐temperature static tensile mechanical properties, thermal stability, dynamic thermomechanical properties, density, and heat of detonation of fully‐formulated double‐base propellant with ETPE were studied. It was found that the double‐base propellant with 1 % GAPA had the best comprehensive performance, and its maximum tensile strength and elongation at break at low temperature (−40 °C) were 56.16 MPa and 10.63 %, respectively. The elongation at break was increased by 10.2 % compared to the double‐base propellant without an energetic plasticizer. Meanwhile, the correlation between dynamic and static mechanical properties of the double‐base propellant with 1 % GAPA was also studied, and the relationship between the dynamic storage modulus and the static tensile strength was obtained.