Longitudinal Elasticity Research Articles

Shear wave elastography to evaluate the effect of serum uric acid levels on carotid artery elasticity in patients with high-normal blood pressure

Background: Populations with normal high blood pressure often already have elevated blood uric acid levels and a higher chance of developing atherosclerosis, which accelerates the process of cardiovascular disease. The risk of atherosclerosis increases with thickening of the carotid artery intima-media, and changes in carotid artery elasticity precede intima-media changes, so early monitoring of carotid artery elasticity is of great significance in the prevention of cardiovascular disease. Using shear wave elastography (SWE) to evaluate the effect of serum uric acid (SUA) levels on carotid artery elasticity in patients with high-normal blood pressure (BP). Methods: One hundred and fifteen patients with high-normal BP were selected, and then divided into tertiles according to the SUA levels. The left carotid intima-media thickness (IMT), peak systolic velocity (PSV) and diameter of common carotid artery were measured by two-dimensional ultrasound and Doppler flow imaging. Longitudinal elasticity of the left anterior carotid wall was measured by SWE, including the mean values of the minimum elastic modulus (MEmin), maximum elastic modulus (MEmax) and mean elastic modulus (MEmean). Results: IMT, MEmean, MEmin and MEmax were obviously higher in the 3rd tertile (all P < 0.05), while there were no obviously different between the 1st tertile and 2nd tertile. Pearson correlation analysis showed positive correlations between SUA and SWE-related parameters, while there was no correlation with IMT. Multiple linear regression analysis found that age, systolic BP, and SUA levels were independently associated with SWE-related parameters. Conclusion: SWE will be more helpful than IMT in monitoring the effect of blood uric acid levels on carotid artery elasticity in patients with high-normal BP.

The B4C inclusion in Fe-Cu-Ni-Sn-WC for a composites creation applied in ornamental rock cutting tool: a mechanical characterization

In the present work, the experiments carried out aimed at the study and development of a composite based on Fe-Cu-Ni-Sn-WC, with different additions of Boron Carbide. The obtaining of this metallic matrix is intended for the production of pearls, for application in diamond wires used in cutting ornamental rocks. Five compositions were used for the investigation: samples with 2% B4C, 4% B4C, 5% B4C, 8% B4C, and 10% B4C. Initially, rectangular geometry composites were obtained via hot pressing, they were sintered under the same temperature conditions (800°C) and pressure (34MPa). The obtained segments reached approximately 18.00 mm in length, width between 12.80 mm and 15.20 mm, and 3.00 mm in height. The samples were characterized by the mechanical bending test, which allowed the investigation of properties at room temperature, such as yield strength, ultimate tensile strength, longitudinal elasticity modulus, toughness modulus, and resilience modulus. The results showed that the mixture containing 2% B4C presented better overall results. The studies conducted here serve as a basis for the development of new research aimed at producing diamond matrices for use in cutting tools. The inclusion of B4C in Fe-Cu-Ni-Sn-WC composites for creating ornamental rock cutting tools not only enhances efficiency and sustainability in the industry but also promotes significant advances in scientific research and the training of new specialists.

3D knitted fabric as an element of footwear for people with diabetic foot syndrome

This article examines the anthropotechnical design of orthopedic footwear for patients with diabetic foot syndrome. A 3D spacer knitted fabric was used as a barrier between the researcher's foot and the ground. For the purpose of the research, 7–11 mm thick knitted fabrics with longitudinal elasticity from 45–90 kPa were designed and produced on a double-bar warp knitting machine. The FreeMed Professional mat was used to measure the pressures exerted by the foot on a “bare” walking surface and on the surface equipped with the spacer knitted fabric and compared, proving that in the latter case the unit pressure on the patient's foot decreased by 30%. The obtained measurements provide a good starting point for further research on the optimization of loads on human feet.

Widening the frontiers of elastography in biomechanics: simultaneous muscle elasticity measurements at high-sample rate with surface wave elastography

Introduction: In recent years, elastography has become a widely accepted methodology to assess the longitudinal shear elastic modulus of skeletal muscle. Ultrasound shear wave elastography is the gold standard used for such a purpose. However, its low sample rate (1–2 Hz) and the impossibility of being used in several muscles simultaneously limit potential biomechanical applications. In this work, we overcome such limitations by using a surface wave elastography method (NU-SWE).Methods: The NU-SWE comprises a wearable device suitable for measuring several muscles simultaneously. Elasticity can be measured at high-frequency rates (∼15 Hz), by propagating several pulse trains of low-frequency (∼100 Hz) superficial waves separated by a short time interval. These pulses propagate along the medium surface and are recorded by a linear array of vibration sensors placed on the skin of each measured muscle. In this context, this work carried out a proof of concept, showing how NU-SWE enables performing experimental protocols previously impracticable with ultrasound elastography. Thus, we measured the longitudinal shear elasticity of the biceps brachii and brachioradialis muscles simultaneously at 15 Hz during isometric elbow flexions exerted at different torque development rates. Furthermore, for comparison, we measured the electromyographic activity of both muscles.Results: Our results show that the maximum elasticity reached by the brachioradialis increases with contraction rate, while the biceps brachii behaves inversely.Discussion: This study provides new insights concerning muscle synergism, evidenced by changes in muscle elasticity during torque production. More generally, it shows that NU-SWE could help widen elastography-driven research in biomechanics.

Determining the influence of an artificial defect on the mechanical properties of a flexible pipeline material during a rupture test

The object of research is the phenomenon of influence of hidden defects on the mechanical properties of the material of flexible pipelines. T-type pressure fire hoses with an inner diameter of 77 mm were used as test samples of flexible pipelines. During the operation of pressurized fire hydrants and their laying on vertical surfaces, they are subjected to significant bursting pressures in their longitudinal direction. That is, such operating modes of the sleeve may occur during its operation. The research was carried out on the FP 100/1 bursting machine, in which the test samples were fixed. The dependence of the stiffness and normal elasticity of the material of the flexible pipeline on the depth and length of the artificial defect when testing it for breaking has been established. With an artificial defect depth of 0.2 mm and its length from 0 to 40 mm, the stiffness of the flexible pipeline material decreases from 573.812 kN/m to 478.276 kN/m. With the indicated values of the defect, the normal elasticity ranged from 86.46 MPa to 64.567 MPa. When the depth of the defect increases by 0.4 mm, the stiffness of the sleeve material decreases to 432.902 kN/m, and the normal elasticity decreases to 58.442 MPa. The obtained results are explained by the fact that when the thickness of the threads of the base of the power frame is reduced by 33 %, the longitudinal stiffness and normal elasticity of the material of the flexible pipeline are reduced by 25 % and 26 %, respectively. The results of these studies are needed in practice because they can make it possible to develop new or improve existing methods of detecting hidden defects in the material from which flexible pipelines are made

Similar ratio experiment and characteristic analysis of quasi-sandstone

The stability control of surrounding rock in deep roadway is becoming more and more difficult, and grouting reinforcement support has become the mainstream of roadway control. In order to obtain the ratio of quasi-sandstone material corresponding to the grouting body, this paper uses river sand as aggregate, cement and gypsum as cementing agent, retarder and defoamer as additives, and carries out orthogonal proportioning tests with three influencing factors: water-binder ratio (ratio of water to mass of cementing agent), gypsum-cement ratio (ratio of gypsum to mass of cement) and binder-aggregate ratio (ratio of cementing agent to aggregate mass), and compares and analyzes the sensitivity of each factor on the density, compressive strength, tensile strength, elastic modulus, Poisson’s ratio, longitudinal wave velocity, elasticity index and brittleness index of quasi-sandstone material. The results show that 1) the Water-binder ratio has the greatest effect on the sensitivity of material compressive strength, tensile strength, elastic modulus, Poisson’s ratio and longitudinal wave velocity; the gypsum-cement ratio has the greatest effect on the sensitivity of material deformation index and brittleness index; the binder-aggregate ratio has the greatest effect on the sensitivity of material density. 2) Reducing the Water-binder ratio can improve the density, compressive strength and tensile strength of the material; reducing the paste ratio can improve the modulus of elasticity, Poisson’s ratio and longitudinal wave speed of the material; as the gypsum-cement ratio increases, the deformation index first decreases and then increases and then decreases; as the binder-aggregate ratio increases, the brittleness index first increases and then decreases and then increases. 3) The empirical equations between physical and mechanical properties of sandstone-like materials and Water-binder ratio, gypsum-cement ratio and binder-aggregate ratio were established based on multiple linear regression analysis, and more reasonable material ratios were quickly obtained by physical and mechanical parameters of materials. The results of the study provide theoretical references for similar material simulation tests for quasi-sandstone grouting.

Analysis of forced oscillations of wheelset bouncing from multiplicative perturbation specified by harmonic function

The article analyzes the movement of a wheelset along a path that is unequal in length with wave wear of the rails. The authors studied the influence of a force external disturbance on the parametric system “wheel-rail”. The problem under consideration is solved on the basis of a mathematical model of the interaction of a wheel pair and an unequal track, taking into account the additive effect of unequal stiffness on a railway vehicle. It is shown that taking into account the longitudinal uneven elasticity of the railway track makes it possible to more accurately determine the resonant regions and evaluate the decrease or increase in the acceleration level and the amplitudes of bouncing of the unsprung mass of the rolling stock.

Solution of the plane problem of the theory of elasticity on bending of an articulated fixed multilayer panel with a circular axis

This article suggests a method for the solution of the plane problem of the theory of elasticity on the bending of an articulated fixed multilayered panel with a circular axis based on the polynomial approximation of displacements through the thickness of the panel. In contrast to the known solutions of this problem, in this case the coefficients of the approximating polynomials are calculated from the equilibrium conditions and equality of displacements and transverse stresses at the transition across the layer interface and solution of differential equations of equilibrium at several points through the thickness of the layers. Finally, the problem is reduced to the solution of a system of linear equations with respect to the coefficients of approximating polynomials. The validity of the method is confirmed by comparing the results of calculations obtained on its basis and the results obtained with the help of the reference finite element model. The problem is solved in two stages. At the first stage, for a single-layer panel, we investigate the dependence of the polynomial degree on the ratio of the average panel radius to its thickness and the ratio of the transverse shear modulus to the modulus of longitudinal elasticity, which characterize the nonlinearity of displacements. At the second stage, on the example of a three-layered panel, we consider the application of the proposed method for the calculation of multilayered panels. In such case, the results obtained at the first stage are used in selecting the initial degree of polynomials approximating displacements through the thickness of layers. The method proposed in this article makes it possible to obtain an analytical solution without introducing simplifying hypotheses about the nature of displacement of layers and their elastic characteristics in a wide range of variation in geometric dimensions and elastic characteristics of panel layers. This method can be used both for verification of numerical models and for carrying out strength calculations of multilayer panels.

Prediction of the FRP reinforced concrete beam shear capacity by using ELM-CRFOA

In reinforced concrete structures, the utilization of composite rebar has been increased by considering their high corrosion resistance, anti-magnetic properties, and significant tensile strength. According to the lower elasticity modulus of composite rebar in comparison with steel rebar, concrete beams reinforced including composite rebar possess a relatively lower shear strength by comparing with steel rebar. In addition, in concrete beam, reinforced shear failure by composite rebar is commonly brittle and requires precise performance prediction of the members. Thus, the reinforced concrete beams' shear strength by composite rebar is predicted utilizing an Extreme Learning Machine network based on Chaos Red Fox Optimization Algorithm (ELM-CRFOA) according to a wide range of data. The most important parameters, which are considered in this investigation, are the web width, beam effective depth, the strength of concrete compressive, the ratio of the shear span to depth, FRP longitudinal bars elasticity modulus, and ratio of the longitudinal reinforcement. This method's precision has been proved by having a comparison among the model predictions and the accumulated data and available shear design equations. According to the study outcomes, the presented model has precise outcomes in computing the concrete beams' shear strength in comparison with other existing relations. For assessing input parameters' impact on the FRP-reinforced concrete beams' shear strength, a sensitivity analysis is executed.

Determination of the stress-deformed state of a multilayer composite

An analytical determination algorithm was developed in the linear formulation, and a particular case of determining the stress-deformed state of a multilayer composite material was investigated. The algorithm is based on the use of the stress function (Ery) and the dependence of all indicators of the stress-deformed state of the material of each layer on its shape. Possible external factors affecting the composite structure are given. For the general case of building a composite structure, the sequence of adding the matrix of coefficients and the vector of free members of the system of linear algebraic equations is formed. The solution of the system of algebraic equations is proposed to be carried out by a method similar to the pre-race method, but for blocks of four equations supplemented by two equations of the influence of the previous layer in the calculation. As a result of actions similar to direct and reverse pre-race, we will obtain vectors of coefficient values of expressions of indicators of the stress-deformed state of the material of all layers as component sums.
 The acceptability of the algorithm for determining stresses and spatial deformations in a separate case of loading a composite sample with square layers is proven. The possibility of using the algorithm for the case of a significant (infinitely large) thickness the farthest from the loaded layer of the composite structure and single-layer (monolithic) material is shown. The following is established: characteristics of the distribution of normal stresses and displacements in the loaded layer of a two-layer composite material. They qualitatively coincide for different values of the Poisson coefficients of the layer materials. The amplitude of stress relief and displacements across the thickness of the loaded layer increases with a decrease in Poisson's ratio. The ratio of extreme values of normal stresses in the material of the loaded layer depends not only on the ratio of the shear moduli or the longitudinal elasticity moduli but also on the ratio of the values of the Poisson coefficients of the materials of the layers.

Structural and mechanical modeling of density and stiffness of hybrid composite reinforcement

A structural-mechanical analysis of the influence of high-modulus fibers on the physical and mechanical properties of hybrid composite reinforcement has been performed. In the introduction, the need for a detailed physical and mechanical analysis of the properties of combined composite reinforcement is updated due to the insufficient study of many issues. Despite the progress made in the field of modeling structural composite reinforcement and the development of its production technology, many issues related to its strength are not well understood, which is the main constraint in the adoption of scientifically based standards for assigning mechanical characteristics, control and testing methods. The aim of the study is to develop methods and use them to carry out a structural-mechanical analysis of the influence of the type and content of high-modulus fibers on the density and elastic moduli of hybrid composite reinforcement. In the main part of the article, mathematical modeling of the possible mechanism of destruction of combined rods with different content of high-modulus reinforcing fibers and base fibers was carried out. At the first stage, a structural-mechanical analysis of the factors contributing to the increase in the moduli of longitudinal elasticity described by the “rule of mixtures” was carried out. In this case, the influence of the mass and volume content of high-modulus fibers on the density of the hybrid composite, as well as its moduli of longitudinal and transverse elasticity, was modeled. The results obtained make it possible to modernize the method of predictive assessment of the density and elasticity moduli of composite building reinforcement and can be used by engineering and technical workers of manufacturers and consumers of such reinforcement, as well as in the educational process in the training of engineering personnel of the construction profile.

A New Preventive Sock for People with Diabetes

Abstract Diabetes is a chronic disease affecting more than 450 million people throughout the world. One of the most encountered complications of diabetes is diabetic foot. This study aimed to determine the proper fiber type and fabric structure to be used in a preventive sock for diabetic patients. Three fiber types (cotton, acrylic, and polyester) and three fabric structures (jersey, piquet, and terry) were determined for this investigation. Samples were tested for fabric thickness, thermal resistance, air permeability, water vapor permeability, coefficient of friction, abrasion resistance, recovery after compression, and longitudinal elasticity. Acquired data were evaluated, and a preventive sock for diabetic patients was developed accordingly. The developed sock was compared with various diabetic sock samples procured from the market in terms of effectiveness.

Longitudinal shear wave elasticity measurements of millimeter-sized biomaterials using a single-element transducer platform.

Temporal variations of the extracellular matrix (ECM) stiffness profoundly impact cellular behaviors, possibly more significantly than the influence of static stiffness. Three-dimensional (3D) cell cultures with tunable matrix stiffness have been utilized to characterize the mechanobiological interactions of elasticity-mediated cellular behaviors. Conventional studies usually perform static interrogations of elasticity at micro-scale resolution. While such studies are essential for investigations of cellular mechanotransduction, few tools are available for depicting the temporal dynamics of the stiffness of the cellular environment, especially for optically turbid millimeter-sized biomaterials. We present a single-element transducer shear wave (SW) elasticity imaging system that is applied to a millimeter-sized, ECM-based cell-laden hydrogel. The single-element ultrasound transducer is used both to generate SWs and to detect their arrival times after being reflected from the side boundaries of the sample. The sample’s shear wave speed (SWS) is calculated by applying a time-of-flight algorithm to the reflected SWs. We use this noninvasive and technically straightforward approach to demonstrate that exposing 3D cancer cell cultures to X-ray irradiation induces a temporal change in the SWS. The proposed platform is appropriate for investigating in vitro how a group of cells remodels their surrounding matrix and how changes to their mechanical properties could affect the embedded cells in optically turbid millimeter-sized biomaterials.

Dynamical Young's Modulus and Internal Friction in Ultra-High Molecular Weight Polyethylene Composites

This work is devoted to the acoustic spectroscopy investigation of self-reinforced ultra-high molecular weight polyethylene composites made of pressed unidirectional sheets stacked orthogonally to each other. The studied samples demonstrate excellent mechanical properties in a wide temperature range from –5 °C to 50 °C. The relative change in the modulus of longitudinal elasticity for all samples in the studied temperature range did not exceed 1.6%. Depending on pressure value that is used at the stage of fabrication, the studied samples demonstrated dynamic Young's modulus values up to 17.8 GPa and internal friction up to 16∙10–2. Quasi-static mechanical properties are measured using the specimens of various shapes by tensile test. The values of Young's modulus, determined in the elastic part of the tension curves, reach 16.9 GPa.

Evaluation of longitudinal wave velocity and elasticity modulus of concrete at different ages considering mixing ratios

Concrete is a material that the mechanical properties of which change over time. This change is due to chemical reactions within the concrete known as hydration. One of these properties is the modulus of elasticity and longitudinal wave velocity, which has a direct relation with the concrete age and its setting. Just after the materials mixing, the concrete setting is fast, and over time its rate decreases. Here, a series of cubic concrete specimens are prepared and changing in longitudinal wave velocity and modulus of elasticity in different ages is monitored during the process of curing and a relationship has been presented. Materials specifications impact and concrete mixing ratios, including the water to cement ratio and fine to coarse aggregates ratio is studied. Ultrasonic wave velocity has been increased faster at early ages of specimens where the concrete setting process is fast and in last days, rates of increasing the longitudinal wave velocity decreases. An increase in the water to cement ratio leads to increases in the longitudinal wave velocity over time. The empirical equations have been formulated as logarithmic curves. These empirical equations have been developed and a model with more efficiency and precision has been presented. These empirical equations can be used in the analytical and numerical analysis of structures. These models can be used to determine the loading time of concrete structures and to predicting their other physical and mechanical properties, such as strength and stiffness.

Experimental approach to modeling of the plasticizing operation in the hot plate welding process

The paper discusses the topic of butt welding of polyurethane drive belts by the hot plate method in the context of modeling the process of this technological operation. Based on the analysis of the butt welding process, a series of studies of the thermomechanical properties of the material from which the belt is made has been planned. The results will be used for mathematical modeling of the welding process, and in particular its most important phase: the plasticizing operation. On this basis, the study of the compression of cylindrical specimens taken from the belt has been performed at two different speeds. Their result is the relationship between the compressive stress σc and the modulus of longitudinal elasticity Ec at compression and: deformation εc, temperature value T, as well as the compressive velocity vc. In the next step, dynamic viscosity η of the belt material was determined based on the results of dynamic thermomechanical analysis. The research work culminated in the attempts to plasticize the material on a hot plate, in conditions similar to the process of industrial welding. These studies were performed at different speeds vpl, resulting in the correlation between the force required for plasticizing Fpl and the value of the speed of the belt end vpl relative to the hot plate heated to a temperature Tp. The obtained results will be used to formulate a mathematical model of plasticizing the material, based on the selected mechanical deformation models.

Non-destructive mechanical characterisation of thin-walled GFRP beams through dynamic testing and model updating

This work deals with a non-destructive approach based on dynamic testing combined with model updating techniques through finite element modelling and optimisation processes to characterise the main elastic constants of a thin-walled glass fibre reinforced polymer (GFRP) C-channel beam. The experimental modal analysis identified nine vibration modes encompassing global modes predominated by coupled flexural-torsional behaviour as well as local flexural ones related to the flanges of the beam. The longitudinal elasticity and in-plane shear moduli were less sensitive to the number of modes, indicating that only the first three modes were enough to obtain a good estimate of these parameters. In contrast, the transverse modulus of elasticity was more affected over the nine modes and the optimisation process became imperative to seek the optimal value. As corroborated by destructive tests, the non-destructive procedure gives an alternative approach for the mechanical characterisation of GFRP members, which can be advantageous for low-cost in situ quality control.

Testing the magnetoactive elastomer sample for compression with the test machine

A sample of a magnetoactive silicone composite with ferromagnetic fillers is examined on a testing machine. The dependences of the change in the values of the moduli of longitudinal elasticity on deformation are plotted for various modes of compression of the sample. The characteristics of the linear and nonlinear dynamics of changes in the moduli of longitudinal elasticity are given as a function of the magnitudes of the deformations of the material during compression. Within the limits of deformation of the sample, which is 24% of its height, the moduli of longitudinal elasticity are linear. The nonlinear nature of the change in the compression modulus occurs when the sample is deformed over 40%. When the compression ratio of the sample was up to 72%, the compression modulus increased by a factor of 9 without the action of a magnetic field and by a factor of 22 under the action of a magnetic field. The influence of the magnetic field on the growth of the compression moduli with the increase in the compression force ranges is shown. The property of the material to self-healing (“shape memory”) was established after testing in the mode of maximum compression of ultimate loads.

Influence of Stacking Sequence on Strength and Stability of Suspension System Control Arm CFRP Laminate Rods.

The paper deals with buckling and strength analysis of suspension system rods made of carbon fibre reinforced polymer (CFRP) laminate. The whole suspension system of urban solar vehicle, Eagle Two, designed by Lodz University of Technology students was considered. The calculations and analysis focused on suspension rods, where the traditional metal material was replaced with CFRP laminate. The influence of layer arrangement on rod strength, static, and dynamic buckling were analysed. The research was conducted using numerical simulations employing finite element method software. The static and dynamic load was considered. The obtained results show that the plies’ order in the laminate influences both the strength and stiffness of the considered rod. The best results considering both failure force and longitudinal elasticity modulus were obtained for the stacking sequences with axially oriented (0°) plies on the outside of the rod.

Initial Management of COVID-19 Outbreak in Mexico

This paper analyzes the initial stage of the pandemic COVID-19 in Mexico. The objective is to test whether the contagion risk perception and the authorities' initial prevention messages influenced the COVID-19 deaths. We estimate longitudinal elasticities of deaths to confirmed COVID-19 cases by accounting for measurement error and endogeneity issues. We find that confirmed cases and poverty levels are endogenous. The limitation arises because of the underreported COVID-19 deaths. Our contribution is to identify an association with the individual and political risk perception to the number of COVID-19 deaths. The results show that municipalities with more confirmed cases aware of being in contact with another person affected by COVID-19 have fewer deaths. However, emergency management, federal and state, had weak effects of reducing the lethality rate. We infer that better individual risk awareness is an essential factor in reducing the number of deaths from COVID-19.