Mechanical Properties Of Materials Research Articles

Material strengths of shear-induced platelet aggregation clots and coagulation clots

Arterial occlusion by thrombosis is the immediate cause of some strokes, heart attacks, and peripheral artery disease. Most prior studies assume that coagulation creates the thrombus. However, a contradiction arises as whole blood (WB) clots from coagulation are too weak to stop arterial blood pressures (> 150 mmHg). We measure the material mechanical properties of elasticity and ultimate strength for Shear-Induced Platelet Aggregation (SIPA) type clots, that form under stenotic arterial hemodynamics in comparison with coagulation clots. The ultimate strength of SIPA clots averaged 4.6 ± 1.3 kPa, while WB coagulation clots had a strength of 0.63 ± 0.3 kPa (p < 0.05). The elastic modulus of SIPA clots was 3.8 ± 1.5 kPa at 1 Hz and 0.5 mm displacement, or 2.8 times higher than WB coagulation clots (1.3 ± 1.2 kPa, p < 0.0001). This study shows that the SIPA thrombi, formed quickly under high shear hemodynamics, is seven-fold stronger and three-fold stiffer compared to WB coagulation clots. A force balance calculation shows a SIPA clot has the strength to resist arterial pressure with a short length of less than 2 mm, consistent with coronary pathology.

Tensile and bond properties at elevated temperatures of a PBO-FRCM composite system for strengthening concrete elements: Experimental and analytical investigations

This paper presents experimental and analytical investigations on the tensile and bond behaviour at elevated temperature of a polypara-phenylene-benzo-bisthiazole (PBO) fabric reinforced cementitious matrix (FRCM) system for strengthening concrete elements. Direct tensile (DT) and single lap direct shear tests (DS) were performed under steady-state conditions at the following temperatures: 20 °C, 85 °C, 150 °C, 230 °C and 300 °C. The results obtained were evaluated in terms of strength, stiffness, ultimate strain, load vs. slip response at the interface PBO FRCM/concrete and failure modes. Overall, the tensile and bond properties were significantly affected by the temperature increase. These results are mainly associated with the reductions of mechanical properties of the FRCM constituent materials as well as the degradation of the interaction between the fibres and the inorganic matrix at elevated temperatures. The experimental results were then used (i) to evaluate the suitability of the Aveston–Cooper–Kelly (ACK) model in describing the tensile response of FRCM at elevated temperatures and (ii) to calibrate temperature-dependent local shear bond stress vs. slip laws for the FRCM-concrete interaction.

Microstructure and cyclic hardening/softening behavior of laser welded high strength steel joints under asymmetrical cyclic loading

The cyclic behavior of materials under load and its influence on the mechanical properties of materials have always been the focus of engineering research. In this study, high strength steel was successfully welded by laser welding. The microstructure of each region of the high strength steel DP590 post-welding was meticulously analyzed. Additionally, 500 cycles of low-cycle fatigue tests of laser welded high strength steel were carried out by using asymmetric stress control method. After fatigue test, tensile test shall be carried out on some samples. Under the specific combination of mean stress and stress amplitude, compare the specimens that have not been fatigue tested with those that have been fatigue tested, the change of properties of laser welded high strength steel joint under asymmetric cyclic load was analyzed. The results showed that, due to cyclic hardening, the tensile strength of the sample increased to 601 MPa and the yield strength to 325 MPa. Compared with the original sample, the tensile strength and yield strength of the sample after asymmetric cycling had increased by 8.65% and 31.3%, respectively.

Numerical simulation of concrete strength based on microstructure and mineral composition analysis using micro-CT and XRD technology

The investigation of mechanical properties in porous materials, such as concrete, has been a significant area of interest in the fields of civil engineering and architecture. Traditional macroscopic mechanical testing methods are limited due to destructive experimental conditions, time-consuming procedures, and the inability to characterize internal structures. To overcome these limitations, researchers have utilized microscopic factors with micro-CT and simulation models. Different simulation methods demand mechanical parameters to effectively model the constituent materials; however, there exists variability in the amount and standard values of these input parameters, which leads to a decrease in the reliability of the obtained results. In order to tackle this issue, a novel approach is proposed, which integrates mineral component analysis using X-ray diffraction (XRD) and establishes coefficients to minimize the number of necessary input parameters. Simulation results demonstrate excellent agreement with experimental measurements, accurately reproducing the stages of elastic deformation, failure, and fracture in the stress-strain curve of concrete. Our findings reveal that changes in the concrete skeletal structure, microstructure, and mineral composition significantly influence compressive strength. Coarse aggregates and high-mechanical-performance minerals, in particular, have a substantial impact. Additionally, the mechanical properties show a significant linear relationship with the strength reduction coefficient of aggregates and concrete cores. In conclusion, the proposed method, combining CT scanning and XRD with FDEM, proves to be a reliable and practical approach for accurately assessing the mechanical properties of concrete. This methodology simplifies the intricate processes associated with the time-intensive parameter calibration, leading to a more efficient parameter allocation procedure. As a result, this method enhances concrete design, promotes a better understanding of parameter impacts, and enables accurate prediction of concrete behavior across diverse scenarios.

New insights into the interpretation of the results of four point bending tests on float glass

AbstractThe four point bending test is one of the most commonly used and standardised tests to determine the mechanical properties of materials. For its use on float glass there are both the ASTM C158-02R17 and European EN 1288-3:2001 standards. However when testing float glass the results tend be a statistical muddle. This impacts the reliability of the design strength of float glass determined using four point bending tests. In an attempt to resolve this problem a series of four point bending tests were conducted which were designed to be more systematic than those previously reported in the literature and which use newly developed digital microscopy techniques for pre- and post-test analysis. By systematically testing, the test results can be divided into different groups based on air side, Sn side and source of failure, allowing the data to be divided into clear and separate statistical groups. Secondly the results can potentially be used to validate the lower bound glass strength theory proposed by Ballarini et al. (J Eng Mech 142(12):04016100, 2016). The glass specimens were industrially cut, ground, chamfered and flat polished on the long sides. Specimens were checked using advanced digital microscopy before and after testing. The results suggest that uni-modal Weibull behaviour only applies above a critical failure stress. Failures at stresses below this critical failure stress as a group have a separate and steeper Weibull slope. This supports Ballarini’s theory for a lower bound failure strength although there are important differences between the air side and Sn side of the specimens which this theory does not currently allow for. These differences seem to be inherent to the differences between the glass and the Sn sides. The results also show that the strength of cut, ground, chamfered and flat polished glass can be high but that inconsistency in process control and the irregular occurrence of surface failures are the main causes for the statistical spread. Digital microscopy can reliably measure the quality of the various surfaces and intersections of surfaces of a glass specimen but there is no absolute relation between the size of a detected defect and the probability that this defect actually leads to failure.

Analytical and Experimental Research for Development of the Airless Tires for Urban Micromobility Means

It is currently recognized that electric vehicles are the optimal type of passenger transport for urban usage. However, there are very few people willing to buy them, since today electric cars are very expensive. So the development of the personal light electric transport segment (electric bicycles, scooters, motorcycles, etc.) becomes very relevant. At the same time, the introduction of new technologies (in particular, 3D printing) and constructions (airless wheels) for their mass production is of particular importance. The range of problems that can be solved by modern additive technologies is expanding every day. FDM technology is one of the most commonly used additive methods. It is not only widely available, but it also provides significant possibilities for decision-making. However, most developments in this area are focused on obtaining the geometric accuracy of shapes without taking into account the mechanical properties of materials used. Therefore, the purpose of this study is to investigate experimentally the influence of filling density of parts manufactured by 3D printing on their mechanical properties and application of obtained results for the production of airless tires by using FDM technology.

Numerical Simulation of Compressive Mechanical Properties of 3D Printed Lattice-Reinforced Cement-Based Composites Based on ABAQUS

Research has established that the incorporation of 3D-printed lattice structures in cement substrates enhances the mechanical properties of cementitious materials. However, given that 3D-printing materials, notably polymers, exhibit varying degrees of mechanical performance under high-temperature conditions, their efficacy is compromised. Notably, at temperatures reaching 150 °C, these materials soften and lose their load-bearing capacity, necessitating further investigation into their compressive mechanical behavior in such environments. This study evaluates the compressibility of cement materials reinforced with lattice structures made from polyamide 6 (PA6) across different structural configurations and ambient temperatures, employing ABAQUS for simulation. Six distinct 3D-printed lattice designs with equivalent volume but varying configurations were tested under ambient temperatures of 20 °C, 50 °C, and 100 °C to assess their impact on compressive properties. The findings indicate that heightened ambient temperatures significantly diminish the reinforcing effect of 3D-printed materials on the properties of cement-based composites.

Analysis of thermomechanical coupled accelerated aging of HTPB propellants

AbstractThis study employed macroscopic uniaxial compression tests at low and medium strain rates, coupled with microscopic electron microscopy, to extensively analyse the impact of thermomechanical coupled aging on the accelerated aging of Hydroxyl‐terminated Polybutadiene (HTPB) propellants, contrasting it with the effects of isolated factors such as heat and dynamic reciprocating force. Results indicate that at various environmental temperatures (323 K, 343 K, and 363 K), thermomechanical coupled aging more significantly affects HTPB propellants than isolated factors. This effect is macroscopically evident in increased ease of deformation, permanent deformation during aging, continual increase in dissipated energy, and a decrease in average stress and ultimate strain post‐aging. Microscopically, the effect predominantly arises from the interplay between matrix thermal degradation and particle fragmentation, which rapidly accumulate and substantially impact the material's macroscopic mechanical properties. Furthermore, as the aging temperature rises, the alterations in both macroscopic mechanical properties and microscopic morphology of HTPB propellants become more pronounced. However, overly high temperatures may swiftly result in substantial material performance deterioration. Consequently, while elevating temperature effectively accelerates thermomechanical aging, the potential adverse effects on material performance must be judiciously considered. This underscores the necessity of balancing temperature regulation with aging efficiency enhancement in HTPB propellants to ensure effective control and quantitative assessment of the aging process, while minimizing material degradation.

Properties of biopolymer blends based on Rugulopteryx okamurae and hydrophobic polycaprolactone (PCL) and hydrophilic acylated soy protein isolated (SPIa).

The present study explored the utilization of Rugulopteryx okamurae (RO), an invasive brown seaweed, as a renewable raw material for plastic materials based on biopolymer blends. The goal of this study was to improve the previously observed poor mechanical properties of materials based on single biopolymer RO. To enhance these properties, two polymers with distinct hydrophobicities were incorporated into the formulation of different blends: hydrophobic polycaprolactone (PCL) and hydrophilic acylated soy protein isolate (SPIa). SPIa was derived from soy protein through a chemical modification process, introducing hydrophilic carboxyl groups. The addition of PCL significantly strengthened the blend, increasing the storage modulus (E'1Hz) from ~ 110 to ~ 250MPa. Conversely, SPIa incorporation resulted in softening, with E' values around 40MPa. Both additives enhanced deformability proportionally to their concentrations, with SPIa exhibiting notably higher deformability, reaching a maximum deformation of ~ 23% for a RO/SPIa ratio of 25/75. In summary, the study demonstrates the feasibility of producing environmentally friendly blend materials based on RO, tailored for specific applications by incorporating suitable additives into the formulation. Therefore, PCL is recommended for applications susceptible to moisture effects, such as packaging, while SPIa is suggested for highly absorbent applications such as personal care or horticulture.

AZ91 Magnesium Alloy CMT Cladding Layer Processed Using Friction Stir Processing: Effect of Traverse Speed on Microstructure and Mechanical Properties

Friction stir processing (FSP) is a solid-state treating method to enhance the mechanical properties of materials by altering their microstructure. In this study, FSP was applied to the AZ91 magnesium alloy cladding layer prepared using cold metal transition (CMT) technology, and the purpose was to investigate the effect of the traverse speed of the H13 steel stirring head under a constant rotation speed on the microstructure and mechanical properties of the cladding layer. The results demonstrated that FSP could effectively decrease the grain size of the cladding layer and lead to the dispersion and dissolution of the coarse β-Mg17Al12 second phase into the α-Mg matrix. The mechanical characteristics of the processed cladding layer were significantly enhanced compared to the unprocessed cladding layer due to the grain refinement and second-phase strengthening induced by FSP. When the stirring head rotation speed was set at 300 r/min, the average microhardness and tensile properties of the specimens showed a tendency of initially increasing and then dropping as the traverse speed increased. The cladding layer, obtained at a traverse speed of 60 mm/min, displayed optimal mechanical properties with an average microhardness, tensile strength, and elongation of 85.6 HV0.1, 278.5 MPa, and 13.4%, respectively.

Effects of Selective Laser Melting Process Parameters on Structural, Mechanical, Tribological and Corrosion Properties of CoCrFeMnNi High Entropy Alloy

AbstractThe structural, tribological, mechanical, corrosion, and other properties of materials produced by laser-based powder bed fusion additive manufacturing methods are significantly affected by production parameters and strategies. Therefore, understanding and controlling the effects of the parameters used in the manufacturing process on the material properties is extremely important for determining optimum production conditions and for saving time and materials. This study aimed to determine the optimal laser parameter values for CoCrFeMnNi high-entropy alloy powders using the selective laser melting (SLM) method. The layer thickness was kept constant during experimentation. 5 different laser powers and 10 varying laser scanning speeds were tested, with hatch spacing from 30 to 90%. After determining the optimal laser parameters for SLM, prismatic samples were fabricated in different build orientations (0°, 45°, and 90°), and subsequently, their structural, mechanical, tribological, and corrosion properties were compared. Melt pool morphology could not be obtained at 20—40 and 60W laser powers and at all laser scanning speeds used at these laser powers. At 100 W laser power, 600 mm/s laser scanning speed, and 70% hatch spacing parameters, an ultimate tensile stress of 550 MPa and elongation of 48% were obtained. Among the samples produced in different build orientations, the sample produced with a 0° build orientation exhibited the highest relative density (99.94%), the highest microhardness (201.2 HV0.1), the lowest friction coefficient (0.7025), and the lowest wear and corrosion rates (0.7875 mpy). Additionally, SLM parameters were evaluated to have a significant impact on the performance of all properties of the samples. Graphical Abstract

Superhydrophobic/ superoleophilic polystyrene-based porous material with superelasticity for highly efficient and continuous oil/water separation in harsh environments

Three-dimensional separation materials with robust physical/chemical stability have great demand for effective and continuous separation of immiscible oil/water mixtures and water-in-oil emulsions, resulting from chemical leakages and discharge of industrial oily wastewaters. Herein, a superelastic polystyrene-based porous material with superhydrophobicity/superoleophilicity was designed and prepared by high internal phase emulsion polymerization to meet the aforementioned requirements. A flexible and hydrophobic aminopropyl terminated polydimethylsiloxane (NH2-PDMS-NH2) segment was introduced into the rigid styrene-divinylbenzene copolymer through 1, 4-conjugate addition reaction with trimethylolpropane triacrylate. The addition of NH2-PDMS-NH2 simultaneously improved the mechanical and hydrophobic properties of the porous material (the water contact angle from 141.2° to 152.2°). The material exhibited outstanding reversible compressibility (80% strain, even in liquid N2 environments) and superhydrophobic stability, even after being repeatedly compressed 100 times, water contact angle still remained above 150°. Meanwhile, the as-prepared material had outstanding hydrophobic stability in corrosive solutions (strong acidic, alkaline, high-salty, and even strong polar solvent), presence of mechanical interference, strong UV radiations, and high/low temperature environments. More importantly, the material could continuously and efficiently separate immiscible oil/water mixture and water-in-oil emulsions under the above conditions, showing huge potential for the large-scale remediation of complex oily wastewaters.

Exploiting Waste towards More Sustainable Flame-Retardant Solutions for Polymers: A Review

The development of sustainable flame retardants is gaining momentum due to their enhanced safety attributes and environmental compatibility. One effective strategy is to use waste materials as a primary source of chemical components, which can help mitigate environmental issues associated with traditional flame retardants. This paper reviews recent research in flame retardancy for waste flame retardants, categorizing them based on waste types like industrial, food, and plant waste. The paper focuses on recent advancements in this area, focusing on their impact on the thermal stability, flame retardancy, smoke suppression, and mechanical properties of polymeric materials. The study also provides a summary of functionalization methodologies used and key factors involved in modifying polymer systems. Finally, their major challenges and prospects for the future are identified.

Layer-by-Layer Construction of Antibacterial and Anticoagulant Blood Contacting Materials.

Vascular transplantation is a common treatment for Cardiovascular disease (CVD). However, the mismatch of mechanical, structural, or microenvironmental properties of materials limits the clinical application. Therefore, the functional construction of artificial vessels or other blood contact materials remains an urgent challenge. In this paper, the composite nanofibers of polycaprolactone (PCL) with dopamine and polyethylenimine (PEI) coating are first prepared, which are further self-assembled by anticoagulant hirudin (rH) and antimicrobial peptide (AMP) of HHC36 through layer-by-layer (LBL) method. The results of FTIR and XPS analysis show that hirudin and AMP are successfully loaded on PEI-PDA/PCL nanofibers and the hydrophilicity is improved. They also show good mechanical properties that the ultimate tensile strength and elongation at break are better than natural blood vessels. The antibacterial results show that the antibacterial effect is still 93% against E. coli on the fifth day because of the stable and continuous release of HHC36 and rH. The performance of anticoagulant activity also exhibited the same results, which APTT is even 9.7s longer in the experimental group than the control group on the fifth day. The novel materials would be effectively solve the formation of thrombosis around artificial blood vessel grafts and the treatment of inflammation.

Dynamic Mechanical Response and Fracture Properties of Rock-Like Materials with Parallel and Intersecting Flaws

Dynamic Mechanical Response and Fracture Properties of Rock-Like Materials with Parallel and Intersecting Flaws

Identification method on the vibration properties of a periodic core sandwich: Thermal impact on the band gap

This paper focuses on the thermal impact of filtering properties on sandwich structures with periodic core. The evolution of the bandgap is carefully studied as a function of temperature. Sandwich structure allows to shear the viscoelastic core layer and increases passive damping. Two polymers are selected for their viscoelastic properties and their adhesion properties with metal surfaces. The mechanical properties, shear modulus G(ω) and loss factor η(ω) of these polymers, are determined at temperature by an inverse method. The periodicity of the sandwich structure is achieved by alternating two materials with specific viscoelastic properties in the core, allowing resonant frequencies to be located in beams creating frequency ranges without resonant peaks. Temperature has a strong influence on the mechanical properties of polymer materials. This is why we felt it was important to be able to carry out a temperature investigation. Numerical finite element modelling is developed considering periodicity and temperature. Periodic sandwich fabricated in our laboratory are tested under thermal conditioned. The results show the importance of considering the effect of temperature. It has a direct impact on the filtering properties obtained by periodic structures.

An Experimental Study on the Mechanical Properties and Microstructure of the Cemented Paste Backfill Made by Coal-Based Solid Wastes and Nanocomposite Fibers under Dry–Wet Cycling

The mechanical properties and microstructure of the cemented paste backfill (CPB) in dry–wet cycle environments are particularly critical in backfill mining. In this study, coal gangue, fly ash, cement, glass fiber, and nano-SiO2 were used to prepare CPB, and dry–wet cycle tests on CPB specimens with different curing ages were conducted. The compressive, tensile, and shear strength of CPB specimens with different curing ages under different dry–wet cycles were analyzed, and the microstructural damage of the specimens was observed by scanning electron microscopy (SEM). The results show that compared with the specimens without dry–wet cycles, the uniaxial compressive strength, tensile strength, and shear strength of the specimens with a curing age of 7 d after seven dry–wet cycles were the smallest, being reduced by 40.22%, 58.25%, and 66.8%, respectively. After seven dry–wet cycles, the compressive, tensile, and shear strength of the specimens with the curing age of 28 d decreased slightly. The SEM results show that with the increasing number of dry–wet cycles, the internal structure of the specimen becomes more and more loose and fragile, and the damage degree of the structural skeleton gradually increases, leading to the poor mechanical properties of CPB specimens. The number of cracks and pores on the specimen surface is relatively limited after a curing age of 28 d, while the occurrence of internal structural damage within the specimen remains insignificant. Therefore, the dry–wet cycle has an important influence on the both mechanical properties and microstructure of CPB. This study provides a reference for the treatment of coal-based solid waste and facilitates the understanding of the mechanical properties of backfill materials under dry–wet cycling conditions.

Numerical simulation on cellular structure and mechanical properties of tungsten particles/polymethyl methacrylate microcellular composites

AbstractMicrocellular composites combine the advantages of composite material and microcellular material. Introducing the inclusion phase into the polymer matrix can optimize the cellular structure and improve the mechanical properties of microcellular materials. This paper focuses on rigid W particles reinforced PMMA microcellular materials, combining compression experiments and meso FE simulations to investigate the structure–property relationship of cellular structure and compressive properties for W/PMMA microcellular composites. The results indicate that W particles promote heterogeneous nucleation, reducing the cell size to 3 μm, and reinforce the PMMA matrix. W particles (10 → 60 wt%) are linearly and exponentially related to compressive modulus and compressive strength of W/PMMA microcellular composites, increased by 49.3% and 19.8%. Void porosity (71% → 48%) is quadratic related to compressive properties of W/PMMA microcellular composites, increased by 109%. Cell sizes (5 → 1 μm, especially smaller than the W particle sizes) are exponentially related to compressive properties of W/PMMA microcellular composites, increased by 38.5%. This work provides theoretical support for the regulation of cellular structure and optimization of mechanical properties of microcellular materials.

Effective characterization for the dynamic indentation and plastic parameters acquisition of metals

As a fundamental test technique for the mechanical properties of materials, indentation shows broad application prospects. Compared to the well-studied quasi-static indentation, relatively few and incomplete studies on the dynamic indentation test and characterization have been performed. In this work, a dynamic indentation test technique based on the split Hopkinson pressure bar system is developed, and the corresponding “three-wave method” is proposed to effectively acquire the time-resolved dynamic indentation load and depth. Systematic indentation tests under different loading rates and indenter cone angles are conducted on typical metal materials such as Cu, α-Fe, and α-Ti. Based on the dynamic indentation contact stiffness analysis and indentation theory the indentation hardness under different loading conditions are determined. A procedure for plastic parameter inversion of metal materials, including strain hardening and strain rate strengthening terms based on dynamic indentation, is provided. The effectiveness is verified by the traditional compression test results, providing a new method for characterizing the dynamic mechanical properties of metal materials.

A probabilistic fatigue life assessment method for wind turbine blade based on Bayesian GPR with the effects of pitch angle

AbstractThe fatigue behavior of large wind turbine blades is complex and stochastic due to their complex structure and operating environment. This paper focuses on developing a probabilistic fatigue life assessment method for wind turbine blades considering the uncertainties from wind velocity, material mechanical properties, pitch angle, and layer thickness. To improve the efficiency of stochastic fatigue behavior analysis of wind turbine blade, unidirectional fluid‐structure coupling (UFSC) and bidirectional fluid‐structure coupling (BFSC) analysis are employed to analyze the stochastic response. Then, Gaussian process regression (GPR) and Bayesian updating are combined to establish the stochastic fatigue behavior prediction model for wind turbine blade. On this basis, a modified S‐N curve formulation is proposed, and the fatigue life of wind turbine blade is analyzed by the modified S‐N curve and compared with the three‐parameter Weibull model. The results indicate that the proposed method for fatigue life assessment has better accuracy. The proposed probabilistic fatigue life assessment method with high accuracy and high efficiency, which is beneficial for the fatigue reliability design of wind turbine blades.