Test Method For Strength Research Articles

Quadriceps Strength Testing Practices & Barriers During Return to Sport from ACL Reconstruction: A Survey of Collegiate Athletic Trainers.

Quadriceps strength is a key outcome for guiding rehabilitation and return to sport-specific activities after ACL reconstruction (ACLR) surgery. 1) Describe the quadriceps strength testing practices and barriers college athletic trainers (ATs) are using and experiencing when returning patients to sport-specific activities after ACLR. 2)Compare testing methods between college ATs working in the National Collegiate Athletic Association (NCAA) Division I setting and other college settings. Cross-sectional. Online survey. 243 full-time collegiate ATs who had primarily overseen/directed an ACLR rehabilitation in the past five years (age: 34.8±10.7, years of AT practice: 11.7±9.3, NCAA division I setting: 56%). Our survey included four sections: Demographics, General ACLR rehabilitation practices, Quadriceps strength testing methods & criteria, and Quadriceps strength testing barriers. Knee muscle strength was the most common (98%) outcome collegiate ATs use when determining whether an ACLR patient is ready to progress to sport-specific activities. Manual muscle testing (MMT) was the most used testing method (57%), followed by isokinetic dynamometry (IKD) (48%), repetition max (RM) testing (35%) and handheld dynamometry (HHD) (22%). Most ATs (63-64%) used >90% side-to-side symmetry as their return to sport-specific activities criteria. Lack of equipment needed (83%), lack of financial means (28%), and lack of training/education (20%) were the barriers that most limited ATs use of IKD testing, the gold-standard testing method. Compared to ATs in other settings, a greater proportion of ATs working in the NCAA Division I setting used IKD testing (65% vs 28%) and a smaller proportion used MMT (47% vs 70%). While almost all college ATs considered knee muscle strength an important outcome to assess when returning patients to sport-specific activities after ACLR, quadriceps strength testing practices were highly variable among ATs and may be impacted by access to necessary resources.

Experimental study on the utilization of Fly ash solid waste in tunnel shotcrete materials

AbstractFly ash has emerged as a prominent solid waste in China, leading to various environmental concerns and posing a threat to the health of living organisms, including humans. To enhance the industrial applicability of this waste material, a novel approach has been proposed wherein sand is replaced with fly ash as the primary raw material for wall grouting of coal mine roadways. To address the issue of low compressive strength and to improve the properties of fly ash shotcrete materials, a method employing an alkali activator to stimulate the chemical activity of fly ash has been put forward. The long‐term effectiveness of the shotcrete material has been evaluated using compressive strength testing and scanning electron microscopy testing methods. The impact of replacing sand with fly ash on the compressive strength of shotcrete and the activation effect of sodium sulfate (Na2SO4), NaOH, and Na2SiO3 on fly ash shotcrete have been studied. The results indicate that the compressive strength of fly ash shotcrete shows optimal improvement when the content of Na2SO4 is 3%. The ideal ratio of cement to fly ash is 1:3. Therefore, incorporating an appropriate amount of alkaline activator could effectively address the compressive strength issues of fly ash shotcrete materials.

An Approach to Improve Specimen Processing for the Flexural Strength Testing of Zirconia.

Measuring the flexural strength of restorative materials such as zirconia is crucial for providing proper indications for clinical applications and predicting performance. Great variations in specimen preparation for flexural strength measurements exist among laboratories. The aim was to evaluate how the processing method, surface treatment, and test method of the specimens affect the flexural strength of zirconia. Zirconia specimens (VITA YZ HT) (n = 270) were processed using CAD/CAM or were conventionally milled with three different surface treatments (machined, ground, polished) and were measured with three-point bending (non-chamfered/chamfered) or biaxial flexural strength test. Weibull statistics were conducted. The mean flexural strength values ranged from 612 MPa (conventional, machined, three-point bending non-chamfered) to 1143 MPa (CAD/CAM, polished, biaxial flexural strength). The highest reliability is achieved when specimens are prepared using thoroughly controllable processing with CAD/CAM and subsequently polished. Higher strength values are achieved with the biaxial flexural strength test method because the stress concentration in relation to the effective volume is smaller. Polishing reduces surface microcracks and therefore increases the strength values.

Optimization of silty soil solidification agent ratio and mechanism of strength change based on design-expert

ABSTRACT In order to achieve the resource utilization of silty soil, based on the solidification mechanism of existing inorganic solidification agents, coal gangue and fly ash were selected as substrates, and quicklime and sodium silicate were used as activators to study a new type of muddy soil solidification agent. This project adopts mixture experimental design and unconfined compressive strength testing methods, and uses design expert software to analyze each component to obtain independent variable relationship strength prediction formulas. By using scanning electron microscope, Particles (Pores) and Cracks Analysis System, the changes in micro pore structure characteristics of Reinforced soil were obtained. The research results indicate that the relationship between the influence of various variable factors on strength gain is as follows: sodium silicate>calcium oxide>fly ash>coal gangue. As the age increases, the porosity shows a trend of first increasing and then decreasing. It has been revealed that the strength growth of Reinforced soil with curing agents is mainly due to the compaction and filling effects of hydrated calcium silicate, hydrated calcium aluminate, and a small amount of ettringite. This study is expected to provide reference for the solidification of high moisture content muddy soil.

Characterization of self-healing in cement-based materials with a low water-to-cement ratio during subsequent hydration

This study explores the role of subsequent hydration in healing cracks in cement-based materials, focusing on a water-cement ratio of 0.20 and aging up to 1260 days. A novel bond strength testing method and backscattered electron imaging (BSE) analyzed the relationship between bond strength and unhydrated cement. Techniques like X-ray diffraction (XRD), scanning electron microscopy (SEM), and mercury intrusion porosimetry (MIP) helped investigate crystal phase content and microstructural changes. Key findings reveal that subsequent hydration primarily produces calcium hydroxide (CH), calcium carbonate (CaCO3), and C–S–H gel. Bond strength notably increased to 36.08 % at 394 days, with a significant reduction in C3S and C2S phases and increases in CH and CaCO3. The calcium-silicon ratio varied across hydration products, with external products containing the highest ratio. The study demonstrates the transformation of C–S–H gel from low to high density and highlights the cohesive structure formation of CH and C–S–H gel, crucial for crack healing. Porosity showed an initial decrease followed by an increase, peaking at 54.14 % above the initial value. These findings underscore the importance of controlling unhydrated cement content for optimizing self-healing in cement-based materials.

Utilizing an enhanced machine learning approach for geopolymer concrete analysis

ABSTRACT The flyash-based geopolymer concrete has been extensively utilized to minimize carbon emissions for over 15 years. The compressive strength (CS), split tensile strength (STS), and flexural strength (FS) of concrete determine its mechanical characteristics. Laboratory strength testing and analytical methods is costly and time-consuming, which struggle to predict complicated concrete combination CS, STS, and FS. ML models accurately predict CS, STS, FS. To predict the CS, STS, and FS of GPC concrete, five ML techniques (LR, SVM, GPR, EL, and ANN) were adopted. Taylor diagrams and error graphs adopted to represents model performances. The GPR outperforms other models in CS predictions by having the lowest MAE, RMSE, MAPE, and R-values. GPR continues to outperform in STS predictions, with low MAE, RMSE, and MAPE, as well as high R-values. GPR outperforms FS predictions with low MAE, RMSE, MAPE, and high R-values. SVM is excellent since it has a low MAE and RMSE. SVM, GPR, and ANN optimisations keep them competitive. GPR consistently gets the lowest MAPE values across all three tests, indicating that it is a strong model contender. The created model can forecast the mechanical characteristics of geopolymer concrete with ease and better reproducibility.

The Effect of a Coating Sprayed Using Supersonic Flame Coating Technology on the Mechanical Properties and Interface Structure of a Thick Steel/Aluminum Composite Plate during Hot Rolling

Given the characteristics of a thick steel/aluminum composite plate, such as its large thickness and the significant differences between its components, it is difficult to prepare using direct rolling. Instead, a thick steel/coating/aluminum composite plate may be successfully prepared by combining supersonic flame coating technology with a hot rolling composite process. In this study, the interface shear strength test, SEM, EDS, and other detection methods were applied to investigate the effects of the reduction rate and coating thickness on the interface structure and mechanical properties. The results show that under the condition of single-pass direct rolling, the micro-interface of steel/aluminum is improved with an increase in the reduction rate, but the bonding strength of the interface remains poor. After adding the coating, the thickness of the diffusion layer and the shear strength increase significantly. When the coating thickness is reduced to 0.1 mm, the deformation coordination and shear strength of the composite plate are further enhanced under the combined action of mechanical interlocking and metallurgical bonding. The tensile shear fracture is mainly located at the steel/coating interface. The interfacial shear strength reaches 66 MPa, which exceeds the requirements of the US military standard MIL-J-24445A (SH) for steel/aluminum shear strength. The research results thus support the use of this new method for the simple and efficient production of thick steel/aluminum composite plates.

Study on rock strength weakening in multi-stage acid fracturing using continuous strength test

Multi-stage acid fracturing can boost productivity in low-permeability limestone reservoirs, with success hinging on differential etching and the strength of undissolved regions to keep fractures open. Traditional rock strength test methods have strong randomness and error. This study explores the influence of four acid systems (hydrochloric acid, single-phase retarded acid, gelled acid, and emulsified acid) on fracture surface strength based on a new continuous strength test method. The rock strength weakening variation under different acid types and injection conditions was quantified, and the mechanism of single-phase retarded acid slowing down rock strength reduction was revealed. The results indicated that the fracture surfaces were reduced to a lesser extent than in traditional rock mechanical failure studies. Hydrochloric acid caused up to 28% of rock strength depletion, followed by 23% for gelled acid, 18% for emulsified acid, and 11.8% for single-phase retarded acid. Adjusting the acid injection parameters revealed that longitudinal leak-off at the fracture surface changes the rock's strength failure tendency. The microscopic results confirmed that the appropriate acid-rock reaction rate and viscosity are beneficial in reducing strength by forming the dominant wormhole that “siphons” the subsequent acid more profoundly into the formation, thereby reducing the reaction of the acid with the fracture surface. This study can help to understand better the mechanism by which acid reduces the strength of fracture surfaces and can provide guidance for selecting appropriate acid fluids for acid fracturing in low-permeability limestone reservoirs.

The impact of artificial aging using chewing simulator on micro-shear bond strength and micro-leakage of alkasite and bioactive resin based composites: an in-vitro comparative study

Objective The current study was conducted to assess and compare the impact of artificial aging using chewing simulator on the novel bulk fill restorative materials (Cention N) and Bioactive Resin Based Composites (ACTIVA) regarding, micro-shear bond strength and micro-leakage. Tetric N ceram bulk fill composite was used as control. Patients and methods For micro-shear bond strength testing, thirty recently extracted molars were collected, then their occlusal surfaces were cut horizontally using low-speed diamond saw under coolant exposing flat dentin surfaces. Tetric N-Bond adhesive was applied to the dentin surface, then Tygon tubes (three for each tooth) with height 1 mm and internal diameter 1 mm were placed on the flat surfaces, followed by light curing, then the restorative material (10 specimens for each material) was condensed inside the tubes. Half of the specimens is subjected to artificial aging (thermal and dynamic loading using Chewing Simulator). The specimens were mounted in blocks of stones, then placed horizontally in the universal testing machine. The load was applied using a knife-edge chisel till debonding of the composite cylinders from dentin surface. Fifteen extracted human molars were utilized for the purpose of evaluating micro-leakage. A total of thirty class II cavities were meticulously constructed on the mesial and distal surfaces of the teeth. The evaluation of micro-leakage was conducted using a dye penetration test, employing a scoring system ranging from 0 to 4. Results The nonaged specimens of the tested materials did not show significant differences regarding micro-shear bond strength, and micro-leakage. Aging had no significant effect on all of the tested properties in the three tested materials. Conclusion Short-term thermomechaical aging used in this study did not deteriorate micro-shear bond strength and micro-leakage of the tested materials. Alkasite (Cention N) and ACTIVA Bioactive Resin Based Composites are promising materials with physico-mechanical properties comparable to conventional bulk-fill composites. However, further in vitro and in vivo studies are needed to assess the properties of these recently introduced materials.

Desain Beton High Early Strength (HES) dengan Campuran Superplasticizer

High initial strength concrete technology is increasingly developing to meet modern projects requiring fast-hardening concrete. This research highlights the role of superplasticizers in achieving high initial strengths. Superplasticizers, and chemical additives, reduce water, accelerate hardening, and simplify concrete work. The compressive strength test method on cylindrical specimens was carried out at the age of 3, 7, and 28 days. Using 250 ml of superplasticizer per sack of cement, with water reduced by 40%, can achieve the quality of concrete f'c 25 MPa at 28 days old. The results showed that concrete with superplasticizer had higher initial compressive strength, increasing by 31.49% in 3 days, and 18.84% in 7 days compared to normal concrete. However, at 28 days old, compressive strength tends to be the same as normal concrete.

Comparison product of muscle contraction strength measuring device based on specifications and its uses

<p>Currently, technological developments have been used in several health cases. One technology used for health is a tool to measure the strength of muscle contractions. So far, measuring muscle contractions still uses manual methods, namely the measurement muscle strength test method. Apart from that, health workers also measure manually by feeling the muscles to be measured. The need for tools to measure muscle contractions in the medical world is quite large because these tools can be used for various needs of doctors and nurses. There are many commercialized products on the market. The first aim of this article is to review four products that are available on the market. The second aim is to provide an overview of the use of the four products that have been carried out by previous researchers and the results. This article also discusses various aspects of product specifications. The research results show that each product has its own advantages. When we compare these products, it is better for us to return to the kind of product we are looking for. For example, if we want a product with high-class features that is equipped with several games, then we can choose MyoBoy. Myo armband and Trigno™ are used to identify several movement force conditions that are influenced by muscle strength, which has been equipped with an Inertial Measurement Unit (IMU) sensor. MyoWare is used to make bionic hands or bionic legs that can be controlled using electromyography (EMG) and has a relatively economical price.</p>

Analysis of the calculation and experimental method for determining the bearing capacity of stone structures

The article presents the results of an experimental study of the stress-strain state of damaged stone columns. It includes an overview of the general research methodology and methods for addressing specific tasks. Detailed descriptions are provided of the strength testing methods for individual elements of brickwork, including bricks and cement-sand mortar. The article also introduces the technology for manufacturing and testing the eccentric compression of stone columns of various cross-sections. A matrix of the conducted experiment is presented, which includes levels and varying factors such as the depth of damage to elements, eccentricity of load application, and angle of inclination of the damage front along one of the principal cross-sectional axes. The experiment's results reveal the most adverse factor affecting load-bearing capacity. Additionally, a calculation and analysis of the safety margin are performed based on the examination of the materials used, which are not considered in calculating the load-bearing capacity of the damaged stone column.

Optimised repairment properties of waterborne epoxy resin–cement composite material: An experimental and simulation study

The demand for high-performance repair materials has significantly increased owing to continuous infrastructure construction. However, current research on epoxy resin–cement mortar composites lacks a theoretical investigation of the proportion of epoxy resin and hardener necessary to prepare a composite material with optimal performance. Composite material preparation often relies on the results of empirical studies. To address this issue, this study used E44 (waterborne epoxy resin, WER) and D230 (hardener) as raw materials to theoretically determine the optimal ratio for preparing a composite material. The optimal ratio and content were validated considering various test parameters, such as workability, mechanical properties, self-developed shear bond strength, and impermeability performance. The results indicated that the epoxy resin-to-hardener ratio of the composite material should be 4:1, with a 30% content. In addition, the microstructure of the composite material was analysed using various test methods, including scanning electron microscopy (SEM), SEM–energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and mercury intrusion porosimetry (MIP), to investigate its influence on the interfacial transition zone (ITZ), composition, and pore structure. Furthermore, molecular dynamics simulations were performed to analyse the mechanical properties, adsorption energy, mean square displacement (MSD), and radius dispersion function (RDF) of the calcium silicate hydrate (C-S-H) and epoxy resin molecule (cross-linked structure) composite, explaining the effect of water molecules on the composite material from an atomic-scale perspective. By combining experimentation and simulation, this study proposes a computational ratio design method that could provide new insights into the research and development of WER–cement composites while creating a simple shear bond strength test method for repair materials.

Inter Tester Reliability of Fitmust Hand Held Dynamometer among Healthy Participants

Background: Strength testing is one of the primary assessment tools for physical strength examination, and an increase in strength is the aim of many rehabilitation programs. Manual muscle testing (MMT) is the most commonly used strength testing method in clinical settings. It is a subjective measurement technique whereby the tester applies resistance to a maximum voluntary muscle contraction. The reliability of the Fitmust hand-held dynamometer is not previously reported in the literature. Aims and Objectives: The study aims to test the reliability of the Fitmust hand-held dynamometer for lower limb muscles in comparison with the Jamar Hand Held dynamometer. Methods: Maximum voluntary isometric contraction of hip extension, knee extension, and plantar flexion is measured by two different therapists on different days using fit must hand-held dynamometer for 40 healthy participants of age category 18- 30 years. Result: Reliability was evaluated by computing Intra-class Correlation Coefficients (ICC), which analyse the consistency between two or more quantitative measures, and Cronbach's Alpha which measured agreement. Conclusion: Inter-tester reliability data obtained for Assessor 1 and 2 were consistent for knee measurements. However, data for the hip and ankle varied considerably. Assessors 1 and 2 demonstrated a 'moderate to excellent' association for knee Measurements.

Asymmetric Four Point Bend Test Method for Interlaminar Shear Strength in Ceramic Matrix Composites

Asymmetrical Four Point Bend test method is proposed for measurement of interlaminar shear strength in continuous fiber reinforced ceramic composites. The current standard ASTM test method (ASTM C1425) for interlaminar shear strength of composites uses a double edge notched compression (DNC) coupon. Large variation in measured strength is observed with the standard ASTM test method, possibly due to machining variability and damage at the notches. The proposed test AFPB method for ILSS is adapted from ASTM C1469 Standard Test Method for Shear Strength of Joints of Advanced Ceramics. This test method does not require any machining of notches and the sample size requirement is much smaller than the ASTM test method. The shear loading in this method is similar to the standard short beam shear test (ASTM D2344) with higher shear to tensile ratio compared to SBS with AFBP. Using finite element analysis, coupon geometry and the distance between the loading and support pins was optimized to maximize shear and minimize tensile and compressive stresses on the specimen. It was found that the variability in the measured ILSS strength was lower with this method compared to the ASTM standard method using the DNC specimen. In addition, the value of ILSS measured using AFPB method was found to be consistently higher than that measured using DNC coupons. It was also found that specimen preparation (cutting, polishing, etc.) did not have significant effect on the measured strength.

A novel test specimen for strength testing of ceramics for additive manufacturing

This paper introduces a new method for strength testing of additively manufactured ceramics, which was designed to take the characteristics of the manufacturing process into account. It was developed for time- and material efficient specimen fabrication and its design allows adjustment so that different surface orientations can be investigated. This gives insight into the influence of surface structures on the measured strength, which vary significantly depending on the surface orientation.Functional expressions for strength evaluation and the determination of effective volume are given and validated through Finite Element Analysis (FEA). The influence of surface structures on the measured strength is analyzed based on Weibull theory and FEA. Other influences on the accuracy of this testing method are discussed and quantified based on practical observations. The manufacturing process, testing setup and statistical evaluation for specimens of three different configurations is outlined and the results and applicability of this method are discussed.

Absolute and relative maximum strength measures show differences in their correlations with sprint and jump performances in trained youth soccer players

Speed strength performances are heavily dependent on maximum strength. However, various strength testing methods determined inconsistent relationships between absolute and relative strength and sprint and jump performances. The aim of the study was to calculate the one tailed correlation coefficients between both the One-Repetition Maximum (1RM) and 1RM in relation to body mass (1RM/BM) in parallel squats and different jump (squat jump and countermovement jump) and sprint performances (5-, 10-, 20-, and 30-m) in youth soccer players (n= 63, 17.9±2.1 years old). Relative strength showed significantly larger correlations with jump performances (r= 0.52 to 0.58) than absolute strength (r= 0.16 to 0.26, z= -1.81 to -1.90, p= 0.029 to 0.035). However, the r values between relative strength measures and sprint performances (r= -0.32 to -0.42) were of non-statistical difference to the correlations of absolute strength measurements with sprint performances (r= -0.19 to -0.3, z= 0.349 to 1.17, p= 0.121 to 0.363). The results of this study support findings in previous literature of enhanced speed strength performances by higher levels of maximal strength in youth soccer players, with faster and more powerful athletes being able to generate larger forces against their own body weight. The data suggests that strength expressed relative to body mass might be considered as a superior predictor of speed strength performance in general.

Determination method of fatigue strength of cement-stabilized Macadam under three-dimensional stress state using equivalent stress as index

The cement-stabilized macadam (CSM) material is in a three-dimensional (3D) complex stress state in the pavement structure. It is difficult for the conventional test method to characterize the 3D fatigue strength characteristics of the CSM. In order to establish a 3D fatigue strength design criterion through simple strength methods, this work conducted the conventional unconfined compressive (UC), direct tensile (DT), and indirect tensile (IT) tests. The corresponding 3D strength model, including three parameters, was determined based on three strength testing methods. In addition, a normalized fatigue model including one parameter was obtained by three fatigue tests. Finally, the fatigue strength model under a 3D stress state was established by combining fatigue and the 3D strength model. The results indicate that the 3D strength model effectively characterized the CSM strength under any stress state, and the difference between the IT strengths predicted by the 3D strength model and obtained by the test is 18.43%. Moreover, the fatigue normalization model reflected the 3D fatigue failure of CSM in a complex stress state. The proposed fatigue strength of CSM based on the equivalent stress has clear physical meaning. This work provided a practical technology to obtain 3D fatigue strength resistance of CSM, which solved the technical problem of inaccurate measurement of pavement structure resistance.

Influence of fibres and hardening accelerator on concrete for rigid pavements

This paper investigates the influence of hardening accelerator and steel fibre on concrete adhesion strength for the repair of rigid highway and airfield pavements. The concretes were mixed based on CEM II/A-S 42.5 and included MasterGlenium SKY 608 superplasticiser. Experiments with two variable concrete composition factors were carried out. The amount of steel fibre varied from 0 to 100 kg/m3 and the amount of SikaRapid hardening accelerator varied from 0 to 9.6 kg/m3. It was found that modified repair concretes have a sufficiently high adhesion strength to ‘old’ concrete, from 2.30 MPa when tested by the pull-off method and from 2.05 MPa when tested by the flexural strength test method. Fibre-reinforcement increases the adhesion strength of repaired concrete by 7–15% due to the reduction of shrinkage during hardening. Treating the contact surface of ‘old’ concrete with a primer additionally increases adhesion strength by 6–10%. The maximum adhesion strength of fibre-reinforced concrete to the base reaches 3 MPa. Due to the high early and design strength, modified steel fibre-reinforced concrete provides the possibility of quick resumption of traffic while ensuring the integrity of the road structure due to the joint work of the repair material with the old concrete repair area.

A Direct Tensile Strength Testing Method for Concrete from Existing Structures

Tensile strength is a crucial property for the function, safety and durability of all concrete structures. The general procedure to assess the tensile properties of concrete from existing structures is to perform indirect tests and predict the tensile strength based on established empirical relationships. In this study, the direct tensile strength of concrete was investigated using cylindrical specimens. The aim of the study was to propose, test and evaluate a general method for direct tensile tests of concrete from existing structures. A total of 16 specimens were tested under deformation-controlled tensile-loading until failure. The concrete samples were prepared with 10 or 15 mm grooves at mid-height to obtain cracking in the groove region, where the crack-opening sensors were installed. The load and corresponding deformation were recorded continuously during the test to obtain the load–crack-width relationship of the concrete. The tests showed that the method can be used to assess the tensile properties of concrete from existing structures. The study provides important insights regarding the assessment of direct tensile strength of concrete and the results can be used to improve the structural health monitoring of existing structures and thereby ensure their safety and durability.