Range Of Elasticity Research Articles

Nuplon: New synthetic polymers fully degradable in water

New crosslinked polyesters, which are fully degradable in the presence of water over several months in the environment, were synthesized by direct polyesterification of multi-hydroxylic alcohols (e.g., pentaerythritol or glycerol), multi-carboxylic acids (e.g., citric acid), and hydroxy acid compounds (e.g., lactic acid). The reaction produced a crosslinked matrix with mechanical properties of solid and useful degradability in the environment. This reaction can be performed with moderate heat (100–200 °C) and without requiring the aid of additional catalysts, inert gas, or vacuum. The crosslinked matrix can be thermoplastic or thermoset, depending on the extent of crosslinking, which is controlled by reaction time and temperature. The polyesters formed with various ratios of the monomers degrade in water in 12 h at 95 °C, 3 days at 70 °C, and about 3 months at 30 °C. These environmentally degradable alkyl polyesters include a range of mechanical strengths and elasticity, making them suitable for various applications. These environmentally degradable, synthetic polymers can replace current non-degradable polymers in various applications. These new polymers are named “Nuplons”.

Phase-field based shape optimization of uni- and multiaxially loaded nature-inspired porous structures while maintaining characteristic properties

Triply periodic minimal surfaces (TPMS) are highly versatile porous formations that can be defined by formulas. Computationally based, load-specific shape optimization enables tailoring these structures for their respective application areas and thereby enhance their potential. In this investigation, individual sheet-based gyroid structures with varying porosities are specifically optimized with respect to their stiffness. A modified phase-field method is employed to establish a simulation framework for the shape optimization process. Despite constant volume and the preservation of the periodicity of the unit cells, volume redistribution occurs through displacement of the interfaces. The phase-field-based optimization process is detailed using unidirectional loading on three gyroidal unit cells with porosities of 75 %, 80 %, and 85 %. Subsequently, the gyroidal unit cell with a porosity of 85 % is shape-optimized under multidirectional loading. A subsequent experimental validation of the unidirectionally loaded cells confirms that the shape-optimized structures exhibit, on average, higher stiffness than the non-optimized structures. The highest increase of 40 % in effective modulus is achieved with the gyroid structure having a porosity of 75 %, while maintaining minimal alteration to the surface-to-volume ratio and preserving periodicity. Additionally, the experimental data show that the optimization process resulted in a shift in the linear elasticity and plasticity range. In summary, the phase-field method proves to be a valid optimization technique for complex porous structures, allowing the preservation of characteristic properties.

Relationship of Physical Factors to the Occurrence of Injuries in Young Gymnasts.

There is a large population of young athletes who participate in gymnastics, and the prevention of injury in junior athletes is considered important. However, few studies have prospectively investigated the relationship between physical factors and the occurrence of injury. To investigate the physical characteristics that are factors in the injury occurrence in elementary and junior high school gymnasts. Prospective observational study. A total of 36 healthy young gymnasts (at national competition level) were enrolled in the study. Once a week for 23 weeks, injuries were prospectively investigated using self-report questionnaires under the supervision of a research staff. Joint range of motion (hip, ankle, shoulder, and wrist), tightness (Thomas test, Ely test, straight leg raise [SLR], triceps surae, combined abduction test [CAT], horizontal flexion test [HFT]), and muscle elasticity (multifidus) were assessed to compare differences in physical function between injured and non-injured participants. Injuries occurred most commonly in the wrist (42.1%), lower back (30.2%), and foot (9.5%) among males, whereas heel (22.2%), knee (16.0%), and lower back (12.8%) were the most common injury sites among females. Wrist injuries in male athletes showed decreased shoulder joint range of motion, and lower back injuries showed decreased hip and shoulder joint range of motion. Lower back injuries in female athletes showed decreased hip extension mobility. Heel and knee joint injuries in females also showed increased range of motion and decreased tightness. The results of this study indicate that the factors related to flexibility differ according to injury location. Further studies are required to clarify the physical factors that influence injury occurrence by examining the effects of the gymnasts' muscle strength, age, individual factors, and left-right differences. 3.

Development of an Energy-Efficient Method of Obtaining Polymer-Modified Bitumen with High Operational Characteristics via Polymer–Bitumen Concentrate Application

New requirements for the operational reliability of roads make the utilization of polymer-modified bitumen (PMB) more common in road construction. The application of polymer-modified bitumen based on traditional technology for the production of asphalt mixtures is associated with technological and economic difficulties and does not provide proper adhesion to the mixture’s mineral components. In addition, the method of producing a binder over a long time at high process temperatures leads to increased aging, which significantly reduces the service life of the material in the pavement. This paper presents the results of studies on the effect of polymer–bitumen concentrate (PBC) consisting of styrene–butadiene–styrene, plasticizer, and surfactant on the bitumen characteristics. It has been established that the use of PBC in the bitumen binder leads to an increase in the temperature range of plasticity, softening temperature, elasticity, and cohesive strength with a decrease in the viscosity of the modified bitumen. With a complex modifier rational content of 8% by weight of bitumen, the temperature range of plasticity is 79 °C, and elasticity is 82%, which exceeds the parameters of the factory PMB-60 based on SBS polymer. Tests of binders using the Superpave method allow classifying the modified binder to the PG 64-28, which shows an increase in the temperature range of viscoelastic properties by 6 °C compared with the binder produced by traditional methods. Thus, the expediency of using a complex additive containing a polymer and surface-active substances (surfactants) that can be distributed in bitumen without the use of a colloid agitator and plasticizer has been proven to improve the quality of an organic binder.

A porous elastomer with a cavity array for three-dimensional plantar force sensing

Human gait is an important indicator for diagnosis of various movement-related disorders. Three-dimensional (3D) plantar force monitoring enables real-time recording of contact forces in both the normal and tangential directions in each step, providing useful clues for identification of irregular gait patterns or gait-related health issues. Most flexible sensors for gait monitoring focus on contact forces in the normal direction, being limited to detect forces in the tangential direction. Herein we have developed a porous elastomer with a cavity array (PECA) to measure 3D contact forces for gait analysis. The sensor consists of two fabric electrodes and a dielectric layer of porous Ecoflex elastomer containing a 5 × 5 cavity array, forming four parallel-plate capacitor units in a soft construction. Therefore, a 3D force in any arbitrary direction generates four unique capacitive electrical signals. Importantly, the PECA includes a well-designed combination of micrometer-scale pores and millimeter-sized cavities, dramatically improving the detection sensitivity and linear elasticity range. We have demonstrated high sensitivities of 0.41 N−1 and 0.23 N−1 in the normal and tangential directions, respectively. The flexible PECA-based sensors have been tested to sensitively distinguish various standing postures and different stride lengths for gait analysis, promising reliable translation into areas such as healthcare monitoring, sports training, and rehabilitation engineering.

Compression elastography in assessment of bicep muscle stiffness with controlled pressure in healthy adults

Background Ultrasound Shear Elastography (USE) is used to quantify the stiffness of biological tissues by measuring muscle deformation or displacement. Compression Elastography (CE) involves applying pressure to the skin using an ultrasound (US) transducer, resulting in tissue displacement, and is used to assess tissue stiffness based on the principle that compression produces strain. Methods In this study, we estimated the strain in the biceps brachialis of healthy volunteers (n=11) and patients with post-stroke spasticity (n=2). The arms were evaluated using the Tardieu scale and strain measurements were obtained using an ultrasound probe with the elbow flexed at 30°. A semi-automatic algorithm for muscle thickness measurement was employed to qualitatively measure muscle elasticity. The application of controlled pressure from an electromechanical actuator allows for strain estimation without direct intervention by an operator, thereby reducing subjectivity in the results. The main aim of this study was to utilize CE to characterize the normal range of muscle elasticity in the biceps brachialis of healthy volunteers who exhibited no changes and were rated 0 on the modified Tardieu scale. Results The normal range of strain for both healthy male and female volunteers demonstrated an acceptable deviation for each strain measurement, as the standard deviation was considered small and relatively constant (with higher values observed under maximum pressure). The proposed measurement mechanism is sensitive, allowing for the observation of strain differences between healthy and spastic muscles in both men and women. Conclusions Comparison of the average curve for the healthy group with two examples of curves from individuals with spasticity showed evident differences. Thus, it would be worthwhile to continue this research by evaluating a group of subjects with spastic muscles.

Sustainable Bioinspired Helical Fibrous Electronics with Interfacial Bonding, Wide Range Elasticity and High Conductivity

AbstractBecause of the weak interfacial bonding between the substrates and active materials, most stretchable electronics often face the problem of performance destabilization and functional failure, especially under large strains. Herein, a super‐elastic, high conductive and core‐shell nanofibrous helix based on polyurethane (PU), silk fibroin (SF) and liquid metal (LM) is fabricated. Compared with traditional membrane, that the LM@PU/SF fibrous helix shows a wider range of workable strain (1500%) and reversible elasticity (600%) accompany with high conductivity is found. SF is acted as “glue” to strengthen the interfacial bonding between the PU and LM. The good elasticity of the helical structure and PU polymer as well as the fluidity of LM improve the stretchability, reversible elasticity and conductivity of the fibrous helix conductor. Furthermore, an alarming and monitoring apparatus using LM@PU/SF helix as the conductive unit based on multiscale fracture is engineered. This composite nanofibrous helix with ultra‐high conductivity and elasticity, making it a promising candidate for stretchable electronic devices.

Customisable Silicone Vessels and Tissue Phantoms for In Vitro Photoplethysmography Investigations into Cardiovascular Disease.

Age-related vessel deterioration leads to changes in the structure and function of the heart and blood vessels, notably stiffening of vessel walls, increasing the risk of developing cardiovascular disease (CVD), which accounts for 17.9 million global deaths annually. This study describes the fabrication of custom-made silicon vessels with varying mechanical properties (arterial stiffness). The primary objective of this study was to explore how changes in silicone formulations influenced vessel properties and their correlation with features extracted from signals obtained from photoplethysmography (PPG) reflectance sensors in an in vitro setting. Through alterations in the silicone formulations, it was found that it is possible to create elastomers exhibiting an elasticity range of 0.2 MPa to 1.22 MPa. It was observed that altering vessel elasticity significantly impacted PPG signal morphology, particularly reducing amplitude with increasing vessel stiffness (p < 0.001). A p-value of 5.176 × 10-15 and 1.831 × 10-14 was reported in the red and infrared signals, respectively. It has been concluded in this study that a femoral artery can be recreated using the silicone material, with the addition of a softener to achieve the required mechanical properties. This research lays the foundation for future studies to replicate healthy and unhealthy vascular systems. Additional pathologies can be introduced by carefully adjusting the elastomer materials or incorporating geometrical features consistent with various CVDs.

The knowledge of movement experts about stretching effects: Does the science reach practice?

Stretching is performed with numerous purposes in multiple settings such as prevention, rehabilitation, fitness training and sports. Its patterns of use substantially depend on the education and beliefs of health care and exercise professionals as they represent the multiplicators recommending and prescribing interventions to clients, patients and athletes. This study investigated movement experts' knowledge about the scientific evidence on stretching effects. Survey study. A total of 117 exercise and health professionals (physiotherapists, sports scientists, coaches) attending a training convention in Austria (male: n = 44, female: n = 73, 36±11 years) completed a digital survey. With its 22 items, the questionnaire addressed the movement experts' awareness of the evidence on stretching effects regarding a variety of related topics selected based on the findings of topical systematic reviews. The majority of the individuals (57-88%) assumed positive effects of stretching on recovery, prevention of muscle injury, range of motion, muscular imbalance and artery elasticity. No or adverse effects were mostly claimed on bone injury prevention, maximal/explosive strength, and delayed-onset muscle soreness. In only 10 of 22 items, participants' classifications were in accord with the scientific evidence. The awareness of research findings on stretching effects among exercise and health professionals is alarmingly low. Future studies may hence be geared to improve implementation and science communication.

Bending of polymer films: a method for obtaining a compressive modulus of thin films.

Due to the advent of various foldable electric devices, it is becoming increasingly important to understand the bending properties of film materials. Bending of isotropic materials may be trivial if elastic deformation is small within a range of linear elasticity, which is often the case for bending. However, bending of polymer films, often used in recent foldable devices, may not be the case. Polymer films are frequently fabricated with stretching, which induces anisotropic orientation of molecular chains. In addition, there are many studies on bimodulus materials, which suggest the importance of the difference in tensile and compressive elastic moduli, i.e., the importance of elastic asymmetry, considering that bending involves compression and extension. In this study, we extended the standard linear elastic theory to include elastic anisotropy and elastic asymmetry and developed a method for obtaining compressive moduli of films, which cannot be obtained by a simple compression test because thin films under compression buckle at small strains. Our method is based on a bending test combined with a uniaxial tension test, which allows the measurement of Poisson's ratio in addition to Young's modulus, which are both anisotropic and asymmetric. To test our theory and method, we further performed experiments on biaxially stretched poly(ethylene terephthalate) (PET) films. As a result, we found non-negligible anisotropy in Poisson's ratio and non-negligible asymmetry (bimodulus) in tensile and compressive moduli. We further justify our framework by demonstrating a clear data collapse to show agreement between experiment and theory, clarifying limitations. Our results suggest the importance of elastic anisotropy and elastic asymmetry in bending of industrial films and give fundamental knowledge on this subject, which would be useful for applications. Such applications include the control of the position of the neutral plane and precise measurements of elastic moduli and Poisson's ratio, which are crucial, e.g., for the development of tough flexible electric devices and for the structural designs using compliant mechanisms.

Reliability analysis of single-story industrial buildings under wind load based on Monte Carlo simulation

Uncertain disasters such as typhoons can affect buildings. Single-storey industrial building is an important type of factory building. In this paper, the reliability of a single storey industrial building under wind load is studied by taking one typical factory in Hunan, China as an example. Firstly, finite element method is used to analyse the structure in the range of linear elasticity. Then, based on Monte Carlo simulation, the probability of failure of the structure under wind load is obtained. The results show that the probability of damage is relatively small, which is also in line with the fact that inland areas are not easily affected by typhoons. In order to obtain a deeper understanding of its reliability, the structural fragility curve considering the variability of steel strength is also studied. The results showed that the smaller the variability of the steel, the more beneficial it is for the reliability of the structure.

Study on Induced Passenger Flow Forecast for Intercity High-Speed Rail

To forecast the induced passenger flow of intercity high-speed rail, two related multinomial logit models are applied to describe travelers’ travel choice behavior under changes in the travel environment. The first model describes different choices of travel mode by travelers between origin–destination pairs, while the second model describes the choice of travel frequency by different travelers. By introducing the consumption surplus variable of travelers, the two selected models are correlated and the model is calibrated using data from a behavioral survey and an intention survey. The results show that the polynomial logit model is applicable for forecasting induced passenger flow after changes in the travel environment. The consumption surplus of travelers is the key factor influencing changes in travel frequency, and the social characteristics of travelers and the economic development features of origin and destination cities have significant impacts on travel frequency. In-transit time is the key factor affecting the demand elasticity of travel frequency. The range of demand elasticity for short-distance business and non-business travel is between −0.61 and −0.79. The results of the demand elasticity analysis were applied to predict that the travel frequency of people from Nanjing to Huai’an, Suqian, Lianyungang, and Yancheng will increase by about 45% after the opening of the Nanjing-Huai’an intercity high-speed railway.

Solving the thoracic inverse problem in the fruit fly

In many insect species, the thoracic exoskeletal structure plays a crucial role in enabling flight. In the dipteran indirect flight mechanism, thoracic cuticle acts as a transmission link between the flight muscles and the wings, and is thought to act as an elastic modulator: improving flight motor efficiency thorough linear or nonlinear resonance. But peering closely into the drivetrain of tiny insects is experimentally difficult, and the nature of this elastic modulation is unclear. Here, we present a new inverse-problem methodology to surmount this difficulty. In a data synthesis process, we integrate literature-reported rigid-wing aerodynamic and musculoskeletal data into a planar oscillator model for the fruit fly Drosophila melanogaster, and use this integrated data to identify several surprising properties of the fly’s thorax. We find that fruit flies likely have an energetic need for motor resonance: absolute power savings due to motor elasticity range from 0%–30% across literature-reported datasets, averaging 16%. However, in all cases, the intrinsic high effective stiffness of the active asynchronous flight muscles accounts for all elastic energy storage required by the wingbeat. The D. melanogaster flight motor should be considered as a system in which the wings are resonant with the elastic effects of the motor’s asynchronous musculature, and not with the elastic effects of the thoracic exoskeleton. We discover also that D. melanogaster wingbeat kinematics show subtle adaptions that ensure that wingbeat load requirements match muscular forcing. Together, these newly-identified properties suggest a novel conceptual model of the fruit fly’s flight motor: a structure that is resonant due to muscular elasticity, and is thereby intensely concerned with ensuring that the primary flight muscles are operating efficiently. Our inverse-problem methodology sheds new light on the complex behaviour of these tiny flight motors, and provides avenues for further studies in a range of other insect species.

The potency of resource efficiency and environmental technologies in carbon neutrality target for Finland

Motivated by Finland's ambitious transition to circular economy through the reduction of consumable non-renewable resources and carbon neutral 2035, this study employs the Fourier approaches of stationarity, cointegration, causality alongside the long-run estimators of fully modified and dynamic least squares to examine the environmental aspects of resource productivity, environmental-related technologies, and export intensity over the period 1990–2020. Interestingly, given the two long-run estimators, the result established that a percent increase in raw material productivity yields a decline in greenhouse gas emission by a range of 61–70 percent. Additionally, there is a desirable and statistically significant impact of environmental-related technologies on greenhouse gas emission with an elasticity range of 0.16–0.18 in the long-run. While the intensity of export activities does not constitute a significant impact, economic growth as measured by Gross Domestic product (GDP) significantly hampers environmental sustainability in the long-run. Moreover, the causality approach including the Fourier Toda Yamamoto offers a strong inference along the insinuation of the long-run results for all the examined factors. Given this observation, relevant policy measures were highlighted to further guide decision makers in Finland on the pursuit of circular economy and carbon zero target.

A Study on Magnetic Soft Materials That Can Reproduce the Wide Range of Elasticity Between Lesions and Normal Biological Tissues

A Study on Magnetic Soft Materials That Can Reproduce the Wide Range of Elasticity Between Lesions and Normal Biological Tissues

Ionic conductive hydroxypropyl methyl cellulose reinforced hydrogels with extreme stretchability, self-adhesion and anti-freezing ability for highly sensitive skin-like sensors

Ionically-conductive hydrogels are attracting increasing interest as skin-like sensors, however, the fabrication of ion-conductive hydrogels with excellent mechanical properties, high conductivity, self-adhesion and anti-freezing ability for high-performance sensors remains a challenge. Herein, a highly ion-conductive hydrogel is prepared by introducing LiCl into polyacrylamide/hydroxypropyl methyl cellulose (PAM/HPMC) composite hydrogel. The introduction of LiCl simultaneously endows the PAM/HPMC/LiCl hydrogel with outstanding stretchability (1453 %), high tensile strength (135 kPa), skin-like elasticity (9.18 kPa), high conductivity (7.85 S/m), good adhesiveness and wide operating temperature range. Impressively, this ion-conductive hydrogel can be utilized in skin-like sensor, which achieves high strain sensitivity (GF = 11.19) with wide sensing ranges (up to 600 %), and excellent endurance over 250 consecutive stretching. As a result, the wearable sensor assembled from the hydrogels can be used to detect complex human activities with high stability even at −40 °C. This work promotes the development of ion-conductive hydrogels with broad operating temperature in advanced sensory platform.

Protocol and reference values for minimal detectable change of MyotonPRO and ultrasound imaging measurements of muscle and subcutaneous tissue

The assessment of muscle health is of paramount importance, as the loss of muscle mass and strength can affect performance. Two non-invasive tools that have been found to be useful in this are the MyotonPRO and rehabilitative ultrasound imaging, both have shown to be reliable in previous studies many of which conducted by the research team. This study aims to determine the reliability of previously unassessed local body structures and to determine their minimal detectable changes (MDC) to support both researchers and clinicians. Twenty healthy participants were recruited to determine the reliability of seven skin positions out of a previously established protocol. Reliability was determined between three independent raters, and day to day reliability was assessed with one rater a week apart. Intraclass Correlation Coefficients (ICC) between raters and between days for tissue stiffness, tone and elasticity range from moderate to excellent (ICC 0.52–0.97), with most good or excellent. ICCs for subcutaneous thickness between days was good or excellent (ICC 0.86–0.91) and moderate to excellent between raters (ICC 0.72–0.96), in muscles it was moderate to excellent between raters and days (ICC 0.71–0.95). The protocol in this study is repeatable with overall good reliability, it also provides established MDC values for several measurement points.

Material, structure, and design of textile-based compression devices for managing chronic edema

Background: Compression bandages, stockings, and pneumatic compression devices are common classifications of compression products, used alone or in combination. The structure of these compression products is complex: they are typically multi-layered, overlapped, stretched and applied to a three-dimensional curved surface part of the body. This research aims to review the materials, designs, and fabrication processes/technologies of a variety of compression devices used in management of chronic edema by considering contributions of materials/textiles, as well as prototyping technologies. Method: Relevant papers/patents for review were identified using keywords associated with materials, designs, and fabrication processes of textile-based compression devices/products for treatments of the edematous lower limb. Results: Modern Compression therapies employ textile materials with a variety of fiber types, yarns and fabric structures, and wide range of elasticity and extensibility (i.e. inelastic to elastic, short stretch to long stretch) to provide the required pressure to the lower leg. Compression fabrics are fabricated using a variety of production technologies and machineries, and they have a wide range of physical and performance attributes. Conclusions: Appropriate selection of materials and fabrication technologies for use in compression therapy is essential to enhance the success in the management of chronic edema. This review might aid in the development and implementation of textiles/materials, and improvement in design of the textile-based compression devices to increase the efficacy of compression therapies in the management of chronic edema, allowing patients to improve their long-term health.

DefGraspSim: Physics-Based Simulation of Grasp Outcomes for 3D Deformable Objects

Robotic grasping of 3D deformable objects (e.g., fruits/vegetables, internal organs, bottles/boxes) is critical for real-world applications such as food processing, robotic surgery, and household automation. However, developing grasp strategies for such objects is uniquely challenging. Unlike rigid objects, deformable objects have infinite degrees of freedom and require field quantities (e.g., deformation, stress) to fully define their state. As these quantities are not easily accessible in the real world, we propose studying interaction with deformable objects through physics-based simulation. As such, we simulate grasps on a wide range of 3D deformable objects using a GPU-based implementation of the corotational finite element method (FEM). To facilitate future research, we open-source our simulated dataset (34 objects, 1e5 Pa elasticity range, 6800 grasp evaluations, 1.1M grasp measurements), as well as a code repository that allows researchers to run our full FEM-based grasp evaluation pipeline on arbitrary 3D object models of their choice. Finally, we demonstrate good correspondence between grasp outcomes on simulated objects and their real counterparts.

Mathematical modeling of the deformation of a cylindrical ring under the influence of an external load distributed along the generatrix

The article is devoted to the mathematical modeling of the deformation of a cylindrical ring under the influence of an external load applied to it by pressing parallel plates. It is shown that at the last stage of oil field operation, the main method of artificial lift is the use of sucker rod pumping units (SRPU), on whose failure-free operation the profitability of oil production largely depends. It is also shown that the technical condition of the SRPU is controlled by the dynamometry method, which is the dependence of the rod string force on the suspension on the stroke of the polished rod. In this case, the main source of information is the force transducer. In the article, we propose using a hollow thick-walled cylinder, which is compressed between traverses consisting of parallel flat plates, as the primary sensitive element of the force transducer. The question of refinement and determination of the non-Hertzian contact deformation during compression of a thick-walled hollow cylinder by two parallel flat plates within the elasticity range is considered. It is shown that the well-known formula for the convergence of the axes of the cylinders being compressed according to the Hertzian method does not take into account the real deformation and convergence of the points of the cylinder due to compression and contact deformation between the generatrices of the cylinders. By solving the differential equation, formulas are derived to determine the value of the elastic deformation of a cylinder depending on its geometric dimensions under the influence of an external load applied to it by pressing plates. An example of calculating elastic deformation for different values of cylinder thicknesses depending on the load is given and its graph is plotted.