Changes In Mechanical Characteristics Research Articles

A Systematic Review of Effects on ACL Injury of Soccer Shoe Outsoles, Soccer Playing Field Surfaces, and Outsole–Surface Interface

Soccer is a sport with a high incidence of injuries. The most common injury occurs when the anterior cruciate ligament of the knee has undergone a sprain, strain, or partial or total rupture. Besides fitness factors (e.g., proprioception, balance and strength capabilities), a principal cause of ACL injuries is sport shoes and playing surfaces. Especially with the emergence of artificial surfaces (rubbers, turfs, concrete, asphalt, red turf), the ACL injuries dramatically increase. The cost of ACL injuries is high both in terms of career termination and in social and economic costs. Thus, it is necessary to understand the impact of sport shoes and playing surfaces on the ACL and how it can be mitigated. The present literature review followed the PRISMA methodology to identify the major biomechanical factors influencing the behavior of surfaces and shoes in relation to the ACL damage. Fifty-eight papers were identified. After reviewing the mechanism of injuries, we identified several distinct factors: type of outsole and mechanical arrangement of the outsoles; shear forces; characteristics of artificial turf surfaces; effect of weather on artificial surface aging and change in mechanical characteristics; outsole/ground interface; and the frictional, tractional and rotational forces in the pathogenesis of ACL injuries in soccer.

The influence of nanosunflower ash and nanowalnut shell ash on sustainable lightweight self-compacting concrete characteristics

The absence of biodegradability exhibited by plastics is a matter of significant concern among environmentalists and scientists on a global scale. Therefore, it is essential to figure out potential pathways for the use of recycled plastics. The prospective applications of its utilisation in concrete are noteworthy. The use of recycled plastic into concrete, either as a partial or complete substitution for natural aggregates, addresses the issue of its proper disposal besides contributing to the preservation of natural aggregate resources. Furthermore, the use of agricultural wastes has been regarded as a very promising waste-based substance in the industry of concrete manufacturing, with the aim of fostering the creation of an environmentally sustainable construction material. This paper illustrates the impact of nano sunflower ash (NSFA) and nano walnut shells ash (NWSA) on durability (compressive strength and density after exposure to 800 °C and sulphate attack), mechanical properties (flexural, splitting tensile and compressive strength) and fresh characteristics (slump flow diameter, T50, V-funnel flow time, L-box height ratio, segregation resistance and density) of lightweight self-compacting concrete (LWSCC). The waste walnut shells and local Iraqi sunflower were calcinated at 700 ± 50 °C for 2 h and milled for 3 h using ball milling for producing NSFA and NWSA. The ball milling succeeded in reducing the particle size lower than 75 nm for NSFA and NWSA. The preparation of seven LWSCC concrete mixes was carried out to obtain a control mix, three mixtures were created using 10%, 20% and 30% NWSA, and the other three mixtures included 10%, 20% and 30% NSFA. The normal weight coarse aggregates were substituted by the plastic waste lightweight coarse aggregate with a ratio of 75%. The fresh LWSCC passing capacity, segregation resistance, and filling capability were evaluated. The hardened characteristics of LWSCC were evaluated by determining the flexural and splitting tensile strength at 7, 14 and 28 days and the compressive strength was measured at 7, 14, 28 and 60 days. Dry density and compressive strength were measured after exposing mixes to a temperature of 800 °C for 3 h and immersed in 10% magnesium sulphate attack. The results demonstrated that the LWSCC mechanical characteristics were reduced when the percentages of NWSA and NSFA increased, except for 10% NWSA substitution ratio which had an increase in splitting tensile strength test and similar flexural strength test to the control mixture. A minor change in mechanical characteristics was observed within the results of LWSCC dry density and compressive strength incorporating various NSFA and NWSA` contents after exposing to temperature 800 °C and immersed in 10% magnesium sulphate attack. Furthermore, according to the findings, it is possible to use a combination of materials consisting of 10–20% NSFA and 10–20% NWSA to produce LWSCC.

CHANGES IN THE STRUCTURE AND PHASE STATE OF ALUMINUM ALLOY 2014, WHICH OCCURRED AS A RESULT OF IRRADIATION WITH AN ELECTRON BEAM

The use of aluminum alloys in nuclear power is limited by the properties of these alloys in the irradiation zone. The use of electron accelerators is an effective technique for simulating real operating conditions. As a result of irradiation, a whole complex of factors begins to work in the targets, which change the properties of these targets. Pulsed electric and magnetic fields appear, shock waves are generated, and gradient heating occurs. All this together changes the structure and properties of the targets. To irradiate the samples, electron beams with an energy of 8.2...8.3 MeV and a beam current of 0.8 mA were used. The work studied changes in the structural-phase state of an aluminum alloy of type 2014. For samples, before and after irradiation, an analysis of changes in mechanical characteristics (hardness, ultimate strength, proof strength) was carried out. Diffractometric studies were performed. These studies made it possible to determine changes in the phase composition. The intensity values of the diffraction lines were obtained.

A qualitative Assessment of the influence of gamma radiation and heating on aluminum using non-destructive examination

The environmental degradation of metals can pose a significant challenge as it can reduce the effectiveness and lifespan of the equipment. As such, there is a growing need for new non-destructive testing methods that can help assess the behavior of materials in harsh environments. This research proposes the use of the non-destructive Scanning Contact Potentiometry (SCP) technique as a real-time monitoring system to control metals that are affected by external factors like gamma radiation and heating conditions. The SCP technique allows for the measurement of localized electro-physical signals on the surface of a material, providing insights into the material's behavior and characteristics. By using SCP as a real-time monitoring system, it is possible to detect changes in the material's behavior and take appropriate actions before any significant damage occurs. The study's findings highlight the effects of gamma radiation and heat on aluminum specimens. The accelerated growth of Al2O3 on the surface of aluminum specimens exposed to doses of up to 400 kGy and 1000 kGy underlines the importance of careful monitoring and maintenance to prevent metal degradation. Similarly, the concurrent changes in mechanical characteristics and oxide development at 150 °C reveal the need for effective management of temperature exposure in industrial settings. This research can contribute to the development of more effective strategies for managing and maintaining industrial equipment and designing new materials, with potential benefits for a wide range of industries.

Use of Logarithmic Decrement of Oscillation Damping for Prediction of the Aviation Structures Service Life

Problem of predicting the residual service life of airplanes and helicopters is highly relevant for flight safety. In this paper, on the basis of the conducted research on the change of mechanical characteristics during materials fatigue accumulation, it is proposed to control the service life by changing the dissipative characteristics. In case of fatigue damage, the accumulative logarithmic decrement of oscillation damping δ increases to the limit maximum value δm, which corresponds to the critical length of the main fatigue crack, which leads to failure. The limit value δm can be set depending on the amount of energy spent on the development of the main fatigue crack, taking into account the dangerous part of the consumed energy. With the accumulation of fatigue damage, the growth of logarithmic decrement occurs at the expense of energy expenditure for the growth of fatigue cracks and internal friction. This is taken into account by the coefficient α, which allows to allocate a dangerous part of the energy that goes into the development of a main fatigue crack. The problem of durability prediction consists of two stages. At first, it is needed to determine δm for the critical crack length. Then, based on the two values of logarithmic decrement at the corresponding load cycles, the number of cycles to failure – to the critical length of the crack – is predicted by the Peris formula

Preliminary assessment of the possibility to use large-diameter pipes of Х52 steel for transportation of pure gaseous hydrogen under pressure

To assess resistance to hydrogen embrittlement caused by the presence of hydrogen in the transported product, and, accordingly, suitability of pipes for hydrogen transport, the base metal of large-diameter pipes of X52 strength class manufactured by JSC “ChelPipe” (part of the PJSC “TMK” group of companies) was studied. The work included the study of pure gaseous hydrogen effect under pressure up to 10 MPa on change in mechanical characteristics of the base metal of large-diameter pipes (LDP) during preliminary hydrogen charging for various time periods in a stationary autoclave under pressure, and during simultaneous loading with a slow strain rate (SSRT) under expected operating conditions. Results of the X52 LDP metal study show that there is no significant impact on the effect of gaseous hydrogen under pressure for up to 144 hours on mechanical characteristics of the base metal determined by static uniaxial tension (decrease in ductile characteristics does not exceed 9 %). During SSRT at a rate of not more than 1·10–6 s–1 in pure gaseous hydrogen environment under a pressure of 10 MPa, the change in strength and ductile characteristics does not exceed 13 % in comparison with reference tests in nitrogen environment under the same pressure. The results obtained allow us to consider that the base metal of low-alloy pipe steel with ferrite-perlite microstructure of X52 strength class is sufficiently resistant to hydrogen embrittlement. Final confirmation of the possibility to use LDP made from steel under study will be the results of further qualification tests, including the study of the weld metal and heat-affected zone properties.

The stress state of the rock mass with spherical cavity

One of the main hypotheses accepted in the mechanics of deformable solids is the assumption of the homogeneity of materials. This means that all mechanical characteristics of the material (modulus of elasticity, Poisson’s ratio, yield strength, relaxation parameters, etc.) are constant over the volume of the body, in other words, these characteristics are constants. This hypothesis makes it possible not to take into account the natural inhomogeneity of materials at the microlevel - the presence of various fractions in composite materials (concrete, fiberglass, etc.), crystal lattice defects, etc. Examples can be given when various physical phenomena (temperature field, radiation exposure, explosive impact, etc.) lead to a change in the mechanical characteristics along the body. These changes can be quite significant. So, for example, in the presence of high-gradient temperature fields, the deformation characteristics of materials at different points of the body can change dozens of times. Thus, when calculating and designing structures, it is necessary to take into account such macro heterogeneity, since it leads to a significant change in the stress-strain state of bodies. This article considers the problem associated with the continuous inhomogeneity of materials. It means such a heterogeneity that arose in the process of creating an underground cavity with the help of an explosion. In contrast to the classical mechanics of a deformable solid body, the problems of which are reduced to differential equations with constant coefficients, in the mechanics of continuously inhomogeneous bodies we deal with equations with variable coefficients, which greatly complicates their solution. In this case, depending on the type of inhomogeneity functions—functions that describe the change in mechanical characteristics along the coordinates—differential equations turn out to be significantly different.

Influence of heating on structure and mechanical characteristics of amorphous Al86Ni9Gd5 ribbons

Changes of structure and mechanical characteristics of amorphous Al86Ni9Gd5 melt-spun ribbons subjected to linear heating at a rate of 10 K/min were investigated by differential scanning calorimetry, X-ray diffraction, transmission electron microscopy, three-point bending testing and microhardness measurements. Non-monotonic changes of all mechanical characteristics were related to the structural variations occurring at three-stage transformation process. It was established that nanocrystallization of amorphous phase led to drop of all properties measured by three-point bend testing (the modulus of elasticity, bending limit at fracture and plasticity) while formation of the intermetallic compounds and coarsening of structure during subsequent transformation stages resulted in their partial recovery. On the contrary, microhardness had a maximum (about 4.5 GPa) in the samples with the ultra-fine grained partially crystallized structure. The potential for practical applications of the established effect of recovery of plasticity from zero in nanocomposite structure to about 1% in the fully crystallized sample with microhardness about 3 GPa was discussed.

Age-associated thin hair displays molecular, structural and mechanical characteristic changes

Hair thinning occurs during normal chronological aging in women and in men leading to an increased level of thinner hair shafts alongside original thicker shafts. However, the characteristics of age-associated thin hairs remain largely unknown. Here we analyzed these characteristics by comparing at multiscale thin and thick hairs originated from Caucasian women older than 50 years. We observed that the cortex of thick hair contains many K35(+)/K38(−) keratinocytes that decrease in number with decreasing hair diameter. Accordingly, X-ray diffraction revealed differences supporting that thin and thick hairs are different with regards to the nature of the intermediate filaments making up their cortices. In addition, we observed a direct correlation between hair ellipticity and diameter with thin hairs having an unexpected round shape compared to the elliptic shape of thick hairs. We also observed fewer cuticle layers and a reduced frequency of a medullae in thin hairs. Regarding mechanical properties, thin hairs exhibited a surprising increased rigidity, a decrease of the viscosity and a decrease of the water diffusion coefficient. Hence, aged-associated thin hairs exhibit numerous modifications likely due to changes of hair differentiation program as evidenced by the modulations in the expression of hair keratins and keratin-associated proteins and by the X-ray diffraction specters. Hence, hair thinning with age does not consist simply of the production of a smaller hair. It is rather a more profound process likely relying on the implementation of an “aged hair program” that takes place within the hair follicle.

Soil micro-penetration resistance as an index of its infiltration processes during rainfall

Rainfall infiltration is one of the most important driving factors of geological hazards, ecological environment problems, and engineering accidents. Understanding the principle of soil wetting during rainfall infiltration and its influence on soil mechanical properties is crucial for preventing geological hazards. In this study, micro-penetration tests coupled with moisture monitoring were performed to investigate the infiltration process during wetting through the measured change in mechanical characteristics. Results show that penetration resistance increases in the deep layer gradually. With increasing infiltration time, the wetting front keeps moving downward, and its range becomes wider. A slight increase of the penetration resistance in the shallow layer ( d ≤ 17.5 mm) is observed. However, the penetration resistance in the middle layer (22.5 mm ≤ d ≤ 32.5 mm) decreases firstly before a slight increase. In the deep layer ( d ≥ 37.5 mm), the penetration resistance decreases continuously during infiltration. Based on the measured water content profile during infiltration, it is found that the evolution of soil mechanical characteristics is fully responsible by the infiltration-induced re-distribution of water content along depth. Generally, the penetration resistance decreases exponentially with increasing water content in the soil. When the water content is low, wetting can weaken soil strength significantly, whereas this effect diminishes when the moisture surpasses a certain threshold. The results highlight that the penetration curves and water content profile show close inter-dependency and consistency, which verifies the feasibility of using micro-penetration to investigate rainfall infiltration and wetting process in surface soil layer or laboratory small-scale soil samples. This method enables fast, versatile and high-resolution measurements of infiltration process and moisture distribution in soil. • Micro-penetration was proposed to study rainfall infiltration in surface soil. • Relationship between soil penetration resistance and water content was established. • Moisture infiltration behavior is different at different depths. • Penetration curve and water content profile show close inter-dependency. • Micro-penetration provides refined investigation of soil hydro-mechanical behavior.

Change of mechanical characteristics in spider silk capture threads after contact with prey

Most spiders rely on specialized capture threads to subdue prey. Cribellate spiders use capture threads, whose adhesion is based on thousands of nanofibers instead of specialized glue. The nanofibers adhere due to van der Waals and hygroscopic forces, but the adhesion is strengthened by an interaction with the cuticular hydrocarbons (CHCs) covering almost all insects. The interaction between CHCs and cribellate threads becomes visible through migration of the CHCs into the thread even far beyond the point of contact. In this study, we were able to show that the migrated CHCs not only influence adhesion but also change the mechanical characteristics of the thread. While adhesion, extensibility and total energy decreased in threads treated with CHCs from different insects, we observed an increasing force required to break threads. Such mechanical changes could be beneficial for the spider: Upon the first impact of the insect in the web, it is important to absorb all the energy without breaking. Afterwards, a reduction in extensibility could cause the insect to stay closer to the web and thus become additionally entangled in neighboring threads. An increased tensile force would additionally ensure that for insects already in the web, it is even harder to free themselves. Taken together, all these changes make it unlikely that cribellate spiders reuse their capture threads, if not reacting rapidly and removing the prey insect before the CHCs can spread across the thread. Statement of significanceCribellate spiders use capture threads that, unlike other spiders, consist of nanofibers and do not rely glue. Instead, prey adheres mainly because their surface compounds, so-called cuticular hydrocarbons (CHCs), interact with the thread, this way generating strong adhesion forces. Previous studies on biomechanics and adhesion of cribellate threads only dealt with artificial surfaces, neglecting any interaction with surface compounds. This study examines the dramatical mechanical changes of a cribellate thread after interaction with prey CHCs, showing modifications of the thread's extensibility, tensile force and total energy. Our results highlight the importance of studying mechanical properties of silk not only in an artificial context, but also in real life.

Determination of Nanoindentation Behavior of HAZ on Glass Material Machined via ECSM Process through Simulation Approach.

The current study develops a numerical model to investigate the nanoindentation behavior of heat-affected zones (HAZ) on glass material produced via the electrochemical spark machining (ECSM) method. Initially, microchannels were created using the ECSM method on soda–lime glass. Following that, a nanoindentation test was conducted to quantify the Young’s modulus and hardness of the glass sample. After that, a numerical model based on finite elements was created to characterize the changes in mechanical characteristics of HAZ. According to the findings, increasing the electrolyte concentration from 10 to 30% increases the intensity of electrochemical discharges, and thereby decreases the hardness of the work material by 16.29 to 30.58% compared to unmachined glass. The results obtained from the simulation are in close agreement with the experimental values. The maximum error obtained between simulation and experimental results is only 4.18%.

Simulation test study on fatigue characteristics of circuit breaker insulation pull rod

The insulation pull rod is the main transmission mechanism of the circuit breaker. In addition to strong electrical performance, it should also have strong mechanical properties. Studying the dynamic characteristics and response insulation pull rods during opening and closing operation and exploring the changes in mechanical characteristics of insulation pull rods during multiple openings and closings are of great significance. In this paper, a 252kV GIS circuit breaker simulator is used to carry out an opening and closing impact fatigue test on an insulation pull rod. The strain signals of the insulation pull rod during the opening and closing stages are obtained. The strain distribution of insulation pulls rod and the influence of operation times on strain are analyzed. The results show that the force on the pull rod is uneven during operation. The force on the mechanism side and contact side is small, and the force on the rod body is large. Also, the pull rod is unstable and bent under pressure force. The impact response frequency is mainly distributed between 0∼1500Hz. With the increase in operation times, the low-frequency component of frequency response basically remains unchanged, while the high-frequency component decreases. After 10000 times opening and closing operations, there was no obvious mechanical loss on the pull rod, but the mechanical properties decreased. The research results can provide reference and basis for the formulation of the performance test method, and specifications of insulating rod materials.

Research of the technological methods influence on the formation of structure and properties during the additive growth of products from nickel chromium steels of the austenitic class by plasma-jet hard facing methods

The paper considers the influence of a change in the heat rate of a source with time by means of slope control, using the example of plasma-jet hard facing, as well as changes in the original structure due to laminated cool post weld upsetting of the pads, using the example of plasma-jet heat-facing with a consumable electrode (Plasma-MIG). It was found that the formation of the structure is accompanied by metal deposits transcrystallization. It is shown that the use of vibratory actions on the liquid bath by slope control modulating during plasma surfacing contributes to the partial suppression of transcrystallization of the metal deposit: the direction of columnar crystallites growth changes relative to the previous layer, contributes to the refinement of the pine-tree structure, which leads to a change in mechanical characteristics. The best properties are observed when surfacing with slope control with a frequency of 15000 Hz. The use of laminated cool post weld upsetting during the plasma-jet hard-facing by consumable electrode reduces the transcrystallization of the metal deposit. It forms dendritic crystals of an equiaxial form, which leads to the reduction of the morphological grain flow, and the strength characteristics of the fused on alloy exceeds the level of the metal durability fused on without post weld upsetting and materials obtained by traditional technologies. However, the moldability characteristics remain at a high level.

The Experimental Study on the Alterations of Hemodynamics and Mechanical Characteristics of Erythrocyte Membrane after Different Training

Background and Aim: The effect on erythrocyte membrane after different training and recovery, by evaluating relationship between the changes of mechanical characteristics of erythrocyte membrane and hemodynamic indices was assessed. Methods: The Sprague Dawley rats were divided into 5 groups (n=7). The rats were trained on treadmill for four weeks, six days per week except for control group that stayed sedentary. The effect of training on hematocrit and mechanical characteristics of the erythrocyte membrane (elasticity and interaction energy) by using dielectrical electrophoresis and the mathematical model were assessed. Results: Training for 3 weeks improved hematocrit and mechanical characteristics after recovery and elasticity and interaction energy in RBC membrane decreased transitorily at different levels after high intensity training. Conclusion: The effect of training in RBC mechanical characteristics is that changes of RBC membrane protein after high-intensity training cause the changes in RBC membrane structure and hence changes hemodynamics.

Failure pressure estimation for an aged and corroded oil and gas pipeline: A finite element study

The mechanical behavior of an aged pipeline, affected by localized and generalized corrosion defects, is investigated using the finite element method. A sample of pipeline steel was aged artificially via an isothermal process (which represents the natural aging transformations), to obtain the mechanical characteristics. In real scenarios, oil and gas pipelines undergo deterioration owing to both aging and corrosion defects.Therefore, this research studies the assessment of failure pressure by combining these two types of deterioration using the finite element method. To calibrate the methodology proposed for estimating the pipeline failure pressure,data from real-scale burst tests published by the Pipeline Research Council International (PRCI) was used. Following the simulations, the initial failure region for each type of defect was determined and analyzed. Similarly, the estimated values of pipeline failure pressure were compared to assess the results obtained through finite element analysis, considering the changes in mechanical characteristics caused by the artificialartificial aging of the steel. In addition, these results were compared with those of certain well-known semiempirical models. Finally, for the different types of corrosion defects investigated in this study, the effects of volumetric loss on the estimation of pipeline failure pressure using finite elements are discussed. The main conclusion of this study is that failure pressure can be estimated more accurately by considering both corrosion defects characteristics and variations in the steel properties caused by aging.

Changes in Mechanical Characteristics of HPC Samples Modified with WC and WO<sub>3</sub> Nanopowder Agglomerates

The paper presents the results of tests of HPC (high performance composites) samples consisting of aramid and glass fabrics modified by agglomerates of WC and WO3 nanopowders. According to the test results, introduction of WC and WO3 powders into the composite plate structure makes it more rigid and elastic, increasing its ability to dissipate energy.

Changes in Mechanical Characteristics of the Right Atrial and Ventricular Myocardium in Monocrotaline-Induced Model of Pulmonary Arterial Hypertension

Changes in Mechanical Characteristics of the Right Atrial and Ventricular Myocardium in Monocrotaline-Induced Model of Pulmonary Arterial Hypertension

Influence of porosity on the fundamental natural frequencies of FG sandwich beams

The concept of functionally graded materials (FGMs) is being actively investigated in sandwich beam design to enhance the durability of the sandwich structure. However, during the manufacturing of FGMs, some technical issues might cause porosities in FGMs, resulting in noticeable changes in mechanical characteristics of sandwich construction. Using an enhanced shear deformable beam theory, the influence of porosity on the fundamental natural frequencies of functionally graded (FG) sandwich beams having simply supported ends is examined in this study. To do so, the material properties of the FG sandwich beam (FGSB) are supposed to change incessantly in conjunction with the thickness, depending on the volume fraction of constituents specified by the modified rule of the mixture, which contains the volume fraction of porosity. The FGSB has two FG face sheets and a homogeneous hardcore (ceramic), and the FGSB has two FGface sheets and a homogeneous softcore (metal) are examined. The outcomes are reported for two constituent metal-ceramic FGSBs with a power-law change of the volume fractions of the constituents across the thickness. Consequently, it is seen that the volume fraction of porosity, power-law index, length to thickness ratio, and the thickness of the FG layer have a substantial impact on the dynamic response of FGSB according to the findings.

Change of Mechanical Characteristics in Spider Silk Capture Threads after Contact with Prey

Change of Mechanical Characteristics in Spider Silk Capture Threads after Contact with Prey