Measurement Of Mechanical Properties Research Articles

Pengaruh Inklusi Karet dan Semen yang Mengandung Graphene Oxide terhadap Perilaku Sifat Fisis dan Mekanis Tanah

Improving the physical properties of problematic soil has became fundamental consideration in various constructions, especially geotechnical engineering, to avoid failures, increase stability and strength of soil. Silty sand is one of the problematic soils and often encountered in the field where the fine gradation contained in the soil allows the soil to easily deform under pressure and lateral forces. In this study, silty sand was mixed with three variations of crumb rubber content (5, 10, and 15% based on soil weight), 6% cement (based on soil weight), and 0.05% graphene oxide (based on cement weight) to measurement and analysis of physical and mechanical properties. Soil Consistency limits, compaction testing using the Proctor Apparatus, and direct shear test were carried out for each mixed variable. The test results showed that the consistency limits and dry density decreases with increasing rubber content in the soil-cement matrix containing graphene oxide. Substitution of graphene oxide into the soil-cement matrix was able to increase in the stress and shear strength of the soil at each in variation in rubber content.

Experimental measurement and simulation of the biaxial mechanical properties of solid propellant HTPB

AbstractHydroxyl‐terminated polybutadiene (HTPB) solid propellant was widely used in carrier rocket and guided missiles, owing to its excellent mechanical properties. The material of HTPB subjected to complex load such as in the process of manufacturing, storage and transportation. Therefore, the mechanical properties of HTPB had important implications for the safety of structure and service life. The purpose of this work is to study the effects of different loading ratios and loading speeds on the biaxial tension of hydroxyl‐terminated polybutadiene (HTPB) solid propellant with a proper kind of biaxial tensile specimen and a high volume fraction three dimensional particle filling model of the material. The proper kind of biaxial tensile specimen with which the stresses in its central part could be obtained with the loads acted on each loading direction was designed and used in the study, and the strains in its central parts were obtained with digital image correlation (DIC) method. The stress‐strain relationship at each direction could be obtained by experiments. Experimental results indicated that the loading speed remarkably influenced the biaxial tensile behaviors of HTPB propellant at room temperature and at different loading ratios. The finite element simulation results demonstrated the accuracy of the biaxial experiment. Based on the experimental results, the particle debonding in biaxial experiments were analyzed and an equivalent Poisson's ratio parameter was proposed to evaluate the degree of debonding. The highly volume fraction three dimensional particle filling model provides a good simulation with experimental results and the equivalent Poisson's ratio parameter can conveniently and accurately determine the debonding of particles which is meaningful to the structure integrity assessment of HTPB solid propellant.

Investigation into the impact of phase composition on the thermal expansion and mechanical properties of Al–Cu–Li alloys

The study employed high-temperature X-ray diffraction, quantitative phase analysis, and tensile mechanical property measurements to investigate the relationship between coefficient of thermal expansion (CTE) and phase composition, along with the average yield strengths and Young's moduli of Al–Cu–Li alloys in three different sheet orientations: 1441, V-1461, V-1469, V-1480, and V-1481. The copper content within the solid solution and the mass fractions of the T1(Al2CuLi) and δ′(Al3Li) phases were determined using an innovative technique based on measuring the lattice distance of the α solid solution, Vegard's law, and balance equations for the elemental and phase compositions of the alloys. It was observed that as the lithium-to-copper ratio in the alloys increased from 0.32 to 1.12, the proportion of the δ′(Al3Li) phase increases from 6.3–8.4 wt.% in V-1481, V-1480 and V-1469 alloys to 16.0–17.3 wt.% in 1441 and V-1461 alloys, accompanied by a decrease in the T1(Al2CuLi) phase from 5 to 1 wt.%. This led to an increase in the Young's modulus from 75 to 77 GPa due to higher overall proportion of intermetallic compounds and a reduction in yield strength from 509 to 367 MPa due to the decrease in the T1 phase. This decrease in yield strength resulted from the fact that the hardening effect of the T1 phase was 3–4 times greater than that of the δ′ phase, and this couldn't be offset by an increase in the total intermetallic compound proportion. The observed increase in Young's modulus indicated that the elastic properties of the intermetallic phases were similar, and the rise in the total fraction of intermetallic compounds compensated for the decrease in the T1 phase. Furthermore, it was demonstrated that СTE, as measured based on the thermal expansion of the solid solution, also depended on the characteristics of the intermetallic phases present in the alloy. This expanded the potential interpretations of СTE measurement results.

In-situ measurement of dynamic micro X-ray CT and dynamic mechanical analysis for rubber materials

Observing the internal state that takes place during deformation is essential for comprehending the mechanical properties of polymeric materials like rubber. For the effective utilization of rubber in damping applications, it is imperative to comprehend the relationship between the loss factor and microstructure. In an earlier study, we developed a dynamic X-ray CT technique tailored for damping materials subjected to tensile amplitude and proposed a method to directly evaluate the internal deformation behavior under dynamic conditions. However, owing to the technical constraints of the shaker employed for dynamic X-ray computed tomography, key variables such as vibration frequency and amplitude could not be incorporated into the analysis. Additionally, it has not been possible to simultaneously measure dynamic viscoelasticity and dynamic micro X-ray CT in situ.In this study, we developed an experimental system that enables simultaneous measurement of dynamic mechanical properties and dynamic X-ray computed tomography (CT). This system facilitates in-situ investigation of internal deformation behavior and the loss factor in rubber materials, allowing for the assessment of variations in loss factors at the micro-scale. We examined the differences between styrene butadiene rubber (SBR) and natural rubber (NR) as base materials and investigated the influence of shape, and particle size of ZnO on the dynamic behavior of SBR composites. Dynamic X-ray computed tomography (CT) was conducted at excitation frequencies of 1 and 2 Hz, excitation amplitudes corresponding to 1% and 1.25% of the inter-chuck distance of the specimens, and a spatial resolution of 0.5 µm. Local strains were extracted from the 3D reconstructed images, and both the local strain amplitudes and their histograms were assessed as characteristics of dynamic behavior. The results indicated that the effect of varying the excitation frequency between 1 and 2 Hz was minimal for the SBR. Additionally, the median value of local strain amplitudes shifted in relation to the magnitude of the excitation amplitude. When comparing base materials (SBR and NR) with significantly different loss factors, no discernible differences were observed in the histograms of local strain amplitudes. The histograms did vary based on the formulation conditions of the SBR microparticle composite, although the loss factor remained unchanged. This lack of change in the loss factor can be attributed to the minimal impact of the particulate composites on the inherent loss factor of pure SBR. Importantly, the study successfully achieved multimodal and simultaneous measurements using dynamic mechanical analysis and dynamic micro X-ray CT.

Magneto-acoustic protein nanostructures for non-invasive imaging of tissue mechanics in vivo

Measuring cellular and tissue mechanics inside intact living organisms is essential for interrogating the roles of force in physiological and disease processes. Current agents for studying the mechanobiology of intact, living organisms are limited by poor light penetration and material stability. Magnetomotive ultrasound is an emerging modality for real-time in vivo imaging of tissue mechanics. Nonetheless, it has poor sensitivity and spatiotemporal resolution. Here we describe magneto-gas vesicles (MGVs), protein nanostructures based on gas vesicles and magnetic nanoparticles that produce differential ultrasound signals in response to varying mechanical properties of surrounding tissues. These hybrid nanomaterials significantly improve signal strength and detection sensitivity. Furthermore, MGVs enable non-invasive, long-term and quantitative measurements of mechanical properties within three-dimensional tissues and in vivo fibrosis models. Using MGVs as novel contrast agents, we demonstrate their potential for non-invasive imaging of tissue elasticity, offering insights into mechanobiology and its application to disease diagnosis and treatment.

Characterization of UVA-irradiated wheat paste and paste-coated paper

Starch paste has been the main adhesive of choice for paper conservation until now. Studies evaluating the properties of paste-coated paper under UVA irradiation conditions are limited but necessary to enable conservators for a proper choice of materials in terms of durability. In this paper, SEM, FTIR, Raman, and measurements of mechanical properties were used to investigate the aging features of UVA-irradiated paste-coated paper. The increased macro and micro physical and chemical changes with increasing UVA exposure time indicated the degradation of paste and paper polymers. The pH and spectroscopic analyses indicated that the carboxyl groups, which led to the acidity of the sample, were slowly produced with increasing irradiation, and the pH of the paste was lower than that of the paper samples when exposed for the same amount of time. The change in crystallinity also affected the degradation rate of paste-coated papers. SEM observations showed that the paste was destroyed more easily than the paper fibers, a higher concentration of paste caused the paper fibers to break, and a lower concentration of paste damaged both the paste and paper fibers. The present study suggests that an appropriate concentration of paste coated on the paper surface could improve the irradiation stability of paper samples for paste-restored paper artifacts.

Contact behaviors involving a nanobeam with surface effect by a rigid indenter

In this study, we present a novel surface model that utilizes surface energy density to predict the surface effect in nanobeam contact problems. To address the issue of a finite-length elastic nanobeam being indented by a rigid cylindrical indenter, we propose an equivalent substitution method. This method allows us to formulate analytical relations between the load and contact half-width for two different boundary cases. The explicit expressions of the contact-zone width, the pressure distribution in the contact zone, the deflection outside the contact zone, and the load–displacement relation are obtained for the nanobeam with surface effect and are compared with classical results in detail. The results show that the influence of the surface effect is very significant for nanobeam contact behavior, especially when the half-width of the contact zone increases and the contact zone becomes two independent symmetric strips. It is also found that the length-height ratio of nanobeam and the end support conditions have a fairly obvious effect on the normalized pressure distribution, which deviates significantly from the one predicted by the classical results due to the surface effect. However, for a given beam length and indenter radius, the ratio of the width of the contact zone to the beam thickness is almost constant, independent of the indenter load and beam boundary conditions. Meanwhile, the model predicts that the contact pressure distribution after the normalization of the average indentation pressure is almost independent of the indentation load and beam boundary conditions, but obviously depends on the surface effect parameters. The present method and result should be helpful not only to the measurement of mechanical properties of the indentation nanobeam but also to the design of the nanobeam-based devices.

Rapid, non-invasive, in vivo measurement of tissue mechanical properties using gravitational loading and a nonlinear virtual fields method.

Measuring the mechanical properties of soft tissues in vivo is important in biomechanics and for diagnosis and staging of diseases, but challenging because it is difficult to control the boundary conditions. We present a novel, non-invasive method for measuring tissue properties using gravitational loading. MRI images of an organ in different positions are registered to measure tissue displacements due to gravitational forces in different positions. Considering equilibrium between stresses and gravity, we established a nonlinear virtual fields method to identify the tissue properties. The method was applied to the human brain as a proof of concept, using an Ogden model. Sensitivity analysis showed that the bulk modulus could be identified accurately while the shear modulus was identified with greater uncertainty; the strains were too small to identify the strain stiffening exponent. The measured properties agreed well with published in vitro data. The technique offers very promising perspectives, allowing the non-invasive measurement of otherwise inaccessible tissues and providing new information such as the bulk modulus under static loading, which has never previously been measured in vivo.

A novel approach to measuring local mechanical properties via photothermal excitation of an atomic force microscope probe using an optical pump–probe inspired design

Obtaining and improving measurements of mechanical properties at the nanoscale has been made possible through the continuous advancement of atomic force microscopy (AFM) techniques over the past several decades. Among these advancements include implementing multifunctional AFM probes and developing new detection schemes that enable sensitivity to local mechanical properties. In this work, we demonstrate a proof-of-concept for a detection scheme that enables a standard AFM configuration to produce qualitative local mechanical property maps through the use of an optical pump–probe scheme, alleviating a common requirement of incorporating additional piezoelectric actuators. Data from this work are presented for silicon carbide and epitaxially grown graphene on silicon carbide. Through preliminary analysis of resonant frequency maps acquired through dual-frequency resonance tracking, the local stiffness and elastic modulus can be estimated at each point. This work contributes to the field of scanning probe microscopy by providing a new opportunity for AFM systems that are not currently equipped for a mechanical mode to obtain local mechanical property data.

Preparation and properties of polyetherimide fibers based on the synergistic effect of carbon nanotubes and ionic liquids

AbstractPolyetherimide (PEI) has been widely applied in the form of plastics, films, and foam materials. But PEI fiber is confronted with some challenges, such as high melt viscosity and high spinning temperature during the spinning process, poor mechanical properties because of its amorphous structure. In this study, ionic liquids (ILs) and carbon nanotubes (CNTs) were used to prepare PEI composite fibers (PEI/CNT‐IL) successfully, which were further characterized by scanning electron microscope (SEM), Raman spectra, differential scanning calorimetry, dynamic mechanical analysis, thermalgravimetric analysis, mechanical property, and conductivity measurements. IL showed a plasticizing effect to reduce the processing temperature of PEI and SEM images showed that CNTs were uniformly dispersed in the PEI matrix by the assistance of IL. The synergistic effect of CNT and IL thus improved the tensile strength and antistatic properties of PEI fibers. When the contents of CNT and IL were 0.5 and 1.0 wt%, respectively, the optimal properties were obtained. PEI/CNT‐IL fibers exhibited a maximum tensile strength of 2.0 cN/dtex with the elongation at break being 90%, and the enhanced electrical conductivity of 10−5 S·cm−1, which was increased by 13 orders of magnitude compared to that of pristine PEI fiber.Highlights PEI composite fibers were prepared via melt spinning with the assistance of IL and CNT. IL can effectively disperse CNT and plasticize PEI to reduce the processing temperature. The synergistic effect of CNT and IL has improved the tensile strength and antistatic properties of PEI fibers.

Characterization of Recycled Aggregates of Concrete and Bricks in the Central Region of Burkina Faso

Aggregates used in the construction of civil engineering works have an impact on the properties of concrete. For several years the central region is famous because of the effects of extraction of natural aggregates on the environment. We conducted laboratory tests on several recycled aggregates of concrete and bricks to determine their mechanical properties. This choice was guided by a concern to identify and analyze the characteristics of natural and recycled aggregates of concretes that impact the properties of concrete on the one hand and to show the importance of increased use of recycled aggregates in concrete production to better preserve the environment and move towards sustainable development moreover. To better understand the qualities of these aggregates, it is necessary for us to carry out experimental tests in the laboratory.
 The objective also guided the choice of the different types of recycled aggregates selected for the measurement of mechanical properties in the central region: Crushed Natural Gravel, Rolled Natural Gravel, Crushed Recycled Gravel, Recycled Spinning Gravel, Alluvionary Natural Sands, Recycled Brick Sands.
 The results show that recycled aggregates of concrete and bricks in the central region can be used for high-quality concretes on the one hand and reduce the impact of artisanal extraction of non-recycled aggregates on the environment on the other hand.
 In short, we retain that the characteristics of recycled aggregates are a function of the rate of mortar gangues glued to the mother aggregates.

Microfluidic Microcirculation Mimetic for Exploring Biophysical Mechanisms of Chemotherapy-Induced Metastasis.

There is rapidly emerging evidence from pre-clinical studies, patient samples and patient subpopulations that certain chemotherapeutics inadvertently produce prometastatic effects. Prior to this, we showed that doxorubicin and daunorubicin stiffen cells before causing cell death, predisposing the cells to clogging and extravasation, the latter being a step in metastasis. Here, we investigate which other anti-cancer drugs might have similar prometastatic effects by altering the biophysical properties of cells. We treated myelogenous (K562) leukemic cancer cells with the drugs nocodazole and hydroxyurea and then measured their mechanical properties using a microfluidic microcirculation mimetic (MMM) device, which mimics aspects of blood circulation and enables the measurement of cell mechanical properties via transit times through the device. We also quantified the morphological properties of cells to explore biophysical mechanisms underlying the MMM results. Results from MMM measurements show that nocodazole- and hydroxyurea-treated K562 cells exhibit significantly altered transit times. Nocodazole caused a significant (p < 0.01) increase in transit times, implying a stiffening of cells. This work shows the feasibility of using an MMM to explore possible biophysical mechanisms that might contribute to chemotherapy-induced metastasis. Our work also suggests cell mechanics as a therapeutic target for much needed antimetastatic strategies in general.

Validation of alkoxysilane-based protective treatments for increasing service life of cementitious materials under different weathering conditions

Gradual degradation of cementitious materials by exposure to the environment decreases the lifespan of buildings, increasing maintenance andrepair costs. Surface treatments based on alkoxysilanes may prevent weathering effects and repair onset damages, though little attention is paid to how the physical-chemical alterations caused by weathering affect their performance.This work reports a comprehensive characterization/validation of an alkoxysilane-based protective treatment on a mortar subjected to different artificial aging processes (freeze-thaw, thermal cycles, carbonation and chlorides), including measurements of water transport, mechanical properties, reaction products and durability under freeze-thaw and sulfate exposure cycles.Formation of compact silica and C-S-H gel structures decreases porosity and water absorption rate with minimal effect on vapor permeability. Bulk mechanical reinforcement and waterproofing are substantially limited on freeze-thaw aged mortars, whereas surface hardness is barely increased for carbonated mortars. These properties were found to effectively increase the mortar resistance against sulfate and freeze-thaw induced damages.

Determining the fundamental failure modes in Ni-rich lithium ion battery cathodes

Challenges associated with in-service mechanical degradation of Li-ion battery cathodes has prompted a transition from polycrystalline to single crystal cathode materials. Whilst for single crystal materials, dislocation-assisted crack formation is assumed to be the dominating failure mechanism throughout battery life, there is little direct information about their mechanical behaviour, and mechanistic understanding remains elusive. Here, we demonstrated, using in situ micromechanical testing, direct measurement of local mechanical properties within LiNi0.8Mn0.1Co0.1O2 single crystalline domains. We elucidated the dislocation slip systems, their critical stresses, and how slip facilitate cracking. We then compared single crystal and polycrystal deformation behaviour. Our findings answer two fundamental questions critical to understanding cathode degradation: What dislocation slip systems operate in Ni-rich cathode materials? And how does slip cause fracture? This knowledge unlocks our ability to develop tools for lifetime prediction and failure risk assessment, as well as in designing novel cathode materials with increased toughness in-service.

Failure analysis and structural fatigue resistance design of multistage centrifugal pump shaft

In the operation of multistage centrifugal pump, the pump shaft of 304 stainless steel is subjected to a variety of alternating loads. It is one of the parts prone to failure. The fracture microscopic observation, chemical composition analysis and mechanical property measurement of the fractured pump shaft are carried out. Through the fracture analysis, it is found that the pump shaft failure is caused by fatigue mechanism with characteristic of multi-source crack initiation, and there are many cavities and inclusions at the fracture. From the numerical analysis, it is found that there is significant stress concentration at the fracture, which exceeds the fatigue limit of the material and eventually leads to the fatigue fracture. Besides, the appropriate fillet radius and elastic coupling are designed for the pump shaft, which can effectively reduce the stress concentration and improve the service life of the pump shaft. Finally, the fatigue life of the improved pump shaft was experimentally verified.

Prediction of mechanical properties of composite materials using multimodal fusion learning

Efficient and accurate measurement of material mechanical properties is important for material development. The mechanical properties of materials are comprehensively affected by factors such as material composition and microstructure. The existing single-mode prediction methods have the problems of poor mapping integrity and low prediction accuracy. In this paper, a multimodal fusion prediction model integrating material microstructure information and material composition information is proposed. Firstly, Convolutional neural network(CNN) is used to extract the material microstructure features, and Multilayer perceptron(MLP) is used to extract the component features. Then, the adaptive feature vector fusion module designed to adjust the influence of different modal information on the mechanical properties is used to achieve high-level feature fusion, and neural network is used to complete the mechanical properties prediction. The method is verified on the data of an alternative composite material. The method proposed provides a promising solution for the measurement and prediction of material properties.

Laser ultrasonic inspection for mechanical properties of materials at high temperature

The measurement of mechanical properties of high-temperature resistant materials at high temperatures is particularly critical, and laser ultrasonic non-destructive testing technology is a prospective approach for measuring mechanical properties in high-temperature environments. Laser ultrasonic propagation models are constructed by finite element analysis, which reveals the effects of different excitation mechanisms on acoustic velocity measurements. It is found that the shear wave in the main propagation direction is hardly detected, and the distinction between shear waves and surface waves in the time domain signal is difficult. Based on the conclusions, the relationships between surface waves, longitudinal waves, and mechanical properties of materials are established by theoretical derivation. According to the propagation characteristics of surface waves and longitudinal waves, the eccentricity detection scheme of the same side and the concentricity detection scheme of the opposite side are, respectively, designed. The velocities of surface waves and longitudinal waves are measured, considering the thermal expansion coefficient and density changes with temperature. The mechanical properties of materials at different temperatures (25–1000 °C) are successfully calculated, and the experimental results are well in accordance with the reference values. It gives a reliable basis for efficient measurement of mechanical properties of materials at high temperatures.

Assessment of inherent heterogeneity effect on continuous mechanical properties of shale via uniaxial compression and scratch test methods

Shale reservoirs have been a significant focus of hydrocarbon production over the past few decades, and the mechanical assessment of target shale reservoirs has been critical to successful field operations, especially in hydraulic fracturing and well completions. The Unconfined compressive strength (UCS) and Poisson's ratio (ν) are critical mechanical properties in shale reservoir assessment. The estimation and measurement of shale mechanical properties are often erroneous by not accounting for their heterogeneous and pre-existing features, which yield variability of shale mechanical properties along their lithostratigraphy. Thus, there is a need to investigate the degree of correlation and accuracy in multiscale mechanical evaluations of heterogeneous shales, and the correlation between such micromechanical and macromechanical measurements. This study investigated the impact of inherent heterogeneity on the measurement of continuous micromechanical and macromechanical properties of shale reservoirs using scratch test (ST) and uniaxial compression test (UCT) methods, and the degree of correlation (correlation coefficient, r) of measurements in shale was further assessed for the variability of their measured properties. Shale core samples from three distinct shale formations were utilized and studied, and the core samples were subjected to ST and UCT, respectively. The results from this study showed that despite inherent heterogeneous anomalies and natural fractures in the shale samples analyzed, there is a good degree of correlation (UCS: r ​= ​0.73; ν: r ​= ​0.89) in the micro- and macro-mechanical properties of shales using two independent experimental tests (ST and UCT). This study provides insights for improving the accuracy of mechanical evaluations and numerical modeling in shales with a high degree of heterogeneity and pre-existing natural fractures. The results indicate that when considering the structural complexity and heterogeneity of unconventional reservoirs such as shales, the ST method can provide a better continuous micromechanical assessment of shales. In contrast, the UCT can provide a better bulk macromechanical measurement of shales.

Direct Measurement of Mechanical Properties of Vitreous Ice by Cryo-FIB.

Direct Measurement of Mechanical Properties of Vitreous Ice by Cryo-FIB.

The Role of the Distance between Fine Non-Metallic Oxide Inclusions on the Fatigue Strength of Low-Carbon Steel

The fatigue strength of steel is an important parameter determining the use of the alloy. Conducting material durability tests depending on the working conditions of the material requires a lot of work. Therefore, the industry knows methods to estimate the fatigue life of steel on the basis of other parameters or measurements of other mechanical properties. One of such parameters is the fatigue strength coefficient, which allows one to link the fatigue strength with the hardness results of a specific steel grade. Alloys produced in industrial conditions contain impurities that can affect the properties of steel, including fatigue strength. Impurities in steel depend mainly on the technology of its production. One of the technologies that allows one to obtain high-purity steel is by subjecting it to secondary metallurgy treatment consisting of desulfurization and refining with argon. The fatigue strength of steel depends, among other things, on the morphology of impurities. In the work, the influence of the distance between small non-metallic inclusions with a diameter of less than 2 µm on the fatigue strength of steel, expressed by the fatigue resistance factor, was assessed. The research was carried out in industrial conditions on seven independent melts of low-carbon steel capable of forming a martensite microstructure. Several dozen fatigue strength tests were carried out for each of the casts. The volume fraction, size, and distribution of pollutants were examined. It was found that the main impurity is Al2O3, with a diameter of about 1.8 µm occurring at a distance of about 12 µm. The distance between small non-metallic inclusions affects the fatigue resistance factor, and small non-metallic inclusions with a diameter of less than 2 µm hinder the destruction of high-ductility steel. The paper presents an example of the structure of non-metallic inclusions for heat, the relative volume of inclusions, the average impurity diameter and impurity spacing for impurity dimensional ranges, the impurity spacing λ for the total volume of impurities, and the bending fatigue strength coefficient tested in steel after hardening and tempering at different tempering temperatures.