Mechanical Testing Of Materials Research Articles

A comparative study on Arc- and vacuum induction-melting for Ti16.6Zr16.6Hf16.6Co10Ni20Cu20 high entropy shape memory Alloy Production

Arc-melting (AM) as a primary method for casting high entropy alloys (HEAs) ensures rapid alloy screening with minimal material input, high cost-effectiveness, and high cooling rates. However, the limitations of AM on a laboratory scale, particularly its constrained sample size and the necessity for remelting steps to ensure homogeneity, hampers thorough mechanical and functional testing of bulk materials. Therefore, this study features a comparative analysis between AM and vacuum induction-melting (VIM) techniques for High Entropy Shape Memory Alloys (HE-SMAs) production, focusing on the senary alloy Ti16.6Zr16.6Hf16.6Co10Ni20Cu20, known for its potential functional applications and high sensitivity to material inhomogeneity. The alloy’s composition, including high-melting point elements like Hf, Ti and Zr, makes it a well-suited candidate for assessing the capabilities of VIM in producing homogeneous bulk materials. The employment of binary pre-alloys in both AM and VIM processes reduced the necessity for remelting steps and ensured better initial quality for subsequent heat treatments. A homogenization treatment at 900 °C for 100 h of an AM-produced senary alloy showed only slight improvements compared to the same alloy produced via VIM, largely due to the slow diffusion of the larger Hf and Zr atoms from the dendrites into the solid solution. This suggests that VIM can achieve comparable levels of homogenization in substantially less time than required for AM-treated samples. The findings finally indicate that by using VIM, when combined with binary pre-alloys, one achieves more homogeneous alloys with reduced heat-treatment time, making it a viable method for HE-SMA production.

Simulation and mechanical testing of 3D printing shin guard composite materials

ABSTRACT This study critically examines the composite material's mechanical properties and performance for 3D-printed shin guards. It contains a thermoplastic polymer matrix with short carbon fibre reinforcement. Shin guard stress and deformation under impact loading were modelled using FEA models. The composite material was 3D-printed and tested for tensile, flexural, and impact properties. The entire cycle of FEA models and careful mechanical testing allows for the development and evaluation of new composite materials and designs. The finite element analysis, such as maximum von Mises stress, is 2890.5 MPa. The carbon fibre-reinforced composite's mechanical properties, including tensile strength, flexural strength, and impact resistance, showed a considerable improvement over those of the unreinforced polymer. The solid design could be heavier and less adaptable than the pattern. Compared to unreinforced polymers, carbon fibre improves strength, stiffness, and impact resistance for the 3D-printed composite. This result thus proves that 3D-printed carbon fibre-reinforced composites could make superior sports protective equipment like shin guards. The FEA calculations and extensive mechanical testing provide a dependable framework for creating and testing these new composite materials and systems.

On the experimental identification of equilibrium relations and the separation of inelastic effects in soft biological tissues

The mechanical characterization of vascular tissues has been mainly focused on the measurement of elastic properties, while the investigation of inelastic effects has received comparatively little attention. Even the relatively simple, purely elastic description of the material behavior requires an appropriate set of experimental data that cannot be easily isolated using standard testing procedures. The presence of viscous and damage-related phenomena poses some challenges in the definition of appropriate testing protocols capable of identifying an equilibrium response, which in general does not solely represent the elastic material behavior. The primary goal of the present study is therefore to devise an experimental procedure that can distinguish and evaluate the different constitutive phenomena separately. To this end, we apply methodologies widely used in the mechanical testing of rubber-like materials and transfer them to the field of biomechanics. We performed two types of experiments in equibiaxial extension on porcine thoracic aorta: a continuous cyclic test followed by a single-step relaxation test and a cyclic multi-step relaxation test, each at varying stretch rates. We demonstrate that the approximation of quasi-stationarity through continuous testing at slow rates is inadequate for the identification of an equilibrium relation. Alternatively, a step-wise protocol allows for the separation of equilibrium and viscous effects. This motivates a thermodynamic discussion of the experimental results in terms of energy dissipation and a closer look at the interplay of inelastic phenomena.

Optimising 4D imaging of fast-oscillating structures using X-ray microtomography with retrospective gating

Imaging the internal architecture of fast-vibrating structures at micrometer scale and kilohertz frequencies poses great challenges for numerous applications, including the study of biological oscillators, mechanical testing of materials, and process engineering. Over the past decade, X-ray microtomography with retrospective gating has shown very promising advances in meeting these challenges. However, breakthroughs are still expected in acquisition and reconstruction procedures to keep improving the spatiotemporal resolution, and study the mechanics of fast-vibrating multiscale structures. Thereby, this works aims to improve this imaging technique by minimising streaking and motion blur artefacts through the optimisation of experimental parameters. For that purpose, we have coupled a numerical approach relying on tomography simulation with vibrating particles with known and ideal 3D geometry (micro-spheres or fibres) with experimental campaigns. These were carried out on soft composites, imaged in synchrotron X-ray beamlines while oscillating up to 400 Hz, thanks to a custom-developed vibromechanical device. This approach yields homogeneous angular sampling of projections and gives reliable predictions of image quality degradation due to motion blur. By overcoming several technical and scientific barriers limiting the feasibility and reproducibility of such investigations, we provide guidelines to enhance gated-CT 4D imaging for the analysis of heterogeneous, high-frequency oscillating materials.

Approaching Standardization: Mechanical Material Testing of Macroscopic Two‐Photon Polymerized Specimens (Adv. Mater. 34/2024)

Approaching Standardization: Mechanical Material Testing of Macroscopic Two‐Photon Polymerized Specimens (Adv. Mater. 34/2024)

Validation of DOE Factorial/Taguchi/Surface Response Models of Mechanical Properties of Synthetic and Natural Fiber Reinforced Epoxy Matrix Hybrid Material.

A validation of the factorial, Taguchi and response surface methodology (RSM) statistical models is developed for the analysis of mechanical tests of hybrid materials, with an epoxy matrix reinforced with natural Chambira fiber and synthetic fibers of glass, carbon and Kevlar. These materials present variability in their properties, so for the validation of the models a research methodology with a quantitative approach based on the statistical process of the design of experiments (DOE) was adopted; for which the sampling is in relation to the design matrix using 90 treatments with three replicates for each of the study variables. The analysis of the models reveals that the greatest pressure is obtained by considering only the source elements that are significant; this is reflected in the increase in the coefficient of determination and in the predictive capacity. The modified factorial model is best suited for the research, since it has an R2 higher than 90% in almost all the evaluated mechanical properties of the material; with respect to the combined optimization of the variables, the model showed an overall contribution of 99.73% and global desirability of 0.7537. These results highlight the effectiveness of the modified factorial model in the analysis of hybrid materials.

Statement of Retraction: Image processing algorithm for mechanical properties testing of high temperature materials based on time‐frequency analysis

Statement of Retraction: Image processing algorithm for mechanical properties testing of high temperature materials based on time‐frequency analysis

Validation of a double-semicircular notched configuration for mechanical testing of orthodontic thermoplastic aligner materials

The potential of using specimens with a double-semicircular-notched configuration for performing tensile tests of orthodontic thermoplastic aligner materials was explored. Unnotched and double-semicircular-notched specimens were loaded in tension using a universal testing machine to determine their tensile strength, while finite element analysis (FEA) and digital image correlation (DIC) were used to estimate stress and strain, respectively. The shape did affect the tensile strength, demonstrating the importance of unifying the form of the specimen. During the elastic phase under tension, double-semicircular-notched specimens showed similar behavior to unnotched specimens. However, great variance was observed in the strain patterns of the unnotched specimens, which exhibited greater chance of end-failure, while the strain patterns of the double-semicircular-notched specimens showed uniformity. Considerable agreement between the theoretical (FEA) and practical models (DIC) further confirmed the validity of the double-semicircular-notched models.

Tribological and mechanical testing of artificial bio-bearing materials followed by design and analysis of patient-specific artificial hip joint

Tribological and mechanical testing of artificial bio-bearing materials followed by design and analysis of patient-specific artificial hip joint

Approaching Standardization: Mechanical Material Testing of Macroscopic Two-Photon Polymerized Specimens.

Two-photon polymerization (2PP) is becoming increasingly established as additive manufacturing technology for microfabrication due to its high-resolution and the feasibility of generating complex parts. Until now, the high resolution of 2PP is also its bottleneck, as it limited throughput and therefore restricted the application to the production of microparts. Thus, mechanical properties of 2PP materials can only be characterized using nonstandardized specialized microtesting methods. Due to recent advances in 2PP technology, it is now possible to produce parts in the size of several millimeters to even centimeters, finally permitting the fabrication of macrosized testing specimens. Besides suitable hardware systems, 2PP materials exhibiting favorable mechanical properties that allow printing of up-scaled parts are strongly demanded. In this work, the up-scalability of three different photopolymers is investigated using a high-throughput 2PP system and low numerical aperture optics. Testing specimens in the cm-range are produced and tested with common or even standardized material testing methods available in conventionally equipped polymer testing labs. Examples of the characterization of mechanical, thermo-mechanical, and fracture properties of 2PP processed materials are shown. Additionally, aspects such as postprocessing and aging are investigated. This lays a foundation for future expansion of the 2PP technology to broader industrial application.

TESTING OF ZIRCONIA FPD FRAMEWORKS FOR FIXED PROSTHESES: MODEL DESIGN AND EVALUATION OF FRACTURE LOAD.

In our previous test model, the abutment teeth and the model base were printed with resin and bonded with a polyether material. Some abutment teeth were fractured during the mechanical load test. Therefore, the aim was to develop and evaluate a new model under mechanical loading until fracture with zirconia FPD frameworks. At a fracture load of up to 1,636 N, neither the artificial abutment teeth nor the base model fractured. Furthermore, the artificial abutment teeth did not detach from the base model. Therefore, the model should be suitable for mechanical testing of most ceramic-based framework materials for three-unit FPDs.

Возрождение объектов исторического наследия на Северном Кавказе в условиях урбанизации

Introduction. The Caucasus attracts tourists with its historical heritage, but many monuments are under threat of destruction due to lack of funding. To preserve the heritage and develop the region, a strategy is needed to create a tourism cluster that will contribute to economic growth and the creation of new jobs. Many countries have used their historical monuments to develop tourism and the economy. In Europe and Asia, projects to reconstruct ancient cities and temples have led to an increase in the flow of tourists. The Caucasus has a unique heritage and can become a successful example. Restoring monuments not only preserves history, but also invests in the future of the region, its economy and cultural diversity. Materials and methods. The authors of this study analyzed a number of legislative initiatives, and also analyzed scientific and literary sources in the field of tourism and monument conservation. In addition to this, they conducted practical research using modern methods of physical and mechanical testing of materials and structures. These studies included quality control methods, as well as the use of modern mathematical tools for summarizing and processing experimental and statistical data. In addition to conducting their own research, the authors also took into account the results of previous scientific research and the experience of successful practices in the field of tourism and restoration of monuments. During the analysis of legislative initiatives, they took into account recent changes in legislation relating to the protection of cultural heritage and stimulation of tourism activities. The combined analysis approach included both theoretical and practical aspects, which contributed to a deeper understanding of issues related to tourism and restoration of monuments. This multifaceted approach also provided more accurate and objective results, supported by evidence and analysis. Results. The work provides an overview of the current state of monuments in the Caucasus region and examines their general characteristics. The essence of tourism as a key factor influencing the development of historically significant territories is analyzed. In this context, current trends in the field of tourism that have an impact on the preservation and restoration of the cultural heritage of the region are also considered. The role of tourism in the development of historical monuments of the Caucasus is undoubtedly high. The tourism potential of this region is based on its rich cultural heritage, which includes architectural masterpieces, ancient monuments and numerous archaeological finds. Discussion. Modern research shows that tourism contributes not only to the preservation, but also to the active restoration of objects of historical significance. Scientific and technical solutions play a key role in the process of restoration and maintenance of cultural monuments of the Caucasus. The use of advanced technologies also includes the use of remote monitoring methods, which allow us to constantly monitor the condition of monuments and quickly respond to any changes. This contributes to more effective and sustainable management of the cultural heritage of the Caucasus, preserving it for future generations. In general, the integration of tourism, scientific and technical solutions into the management and restoration of cultural monuments of the Caucasus region is an important aspect of modern practice, contributing to the preservation of the rich historical heritage of this unique region. Conclusion. Fundamental methods and methodologies were developed for organizing and carrying out work on the preservation and restoration of monuments of historical and cultural heritage. In this context, a scale for assessing damage and destruction has been developed, which makes it possible to more accurately determine the extent of damage and select appropriate methods of restoration measures. Based on current trends in the field of restoration and repair of cultural objects, the study included additional data obtained from the latest research and practical developments in this field. New approaches to repair and restoration requirements have been proposed taking into account modern standards and technologies. Resume. As a result of the research, effective repair and restoration compounds were identified, intended for use in various conditions and taking into account the specifics of specific historical and cultural monuments. These compounds meet the high requirements for preserving the authenticity of objects while ensuring the long-term stability of the restored structures. Suggestions for practical applications and future research directions. The research results can be useful in the repair, restoration and restoration of cultural heritage sites (towers, castles, historical monuments) both in the North Caucasus and beyond.

Fatigue failure prediction through Factor of Safety and Stress concentration in a malfunctioned AISI 4140 Automotive Crankshaft

Abstract The performance and safety of any vehicle relies on proper design of crankshaft. Crankshaft failure occurs mainly due to the combination of imbalance and minor deflections when the materials is subjected to combined bending and twisting. Failure analysis is crucial to identify the causes and modes of failure, in order to improve the service life of automotive crankshafts and prevent accidents. This research analyses the root cause of failure by testing a failed crankshaft of a twin cylinder diesel engine used in mini commercial vehicle runs around 80000 km. The important research gap identified as that there is no fool-proof techniques and validation procedures are followed in the service stations during its life cycle period. This investigation of a failed crankshaft provides detailed composition of material, its micro structure and mechanical properties. Further, rotary analysis, experimental modal analysis and mechanical testing of materials are helpful in characterizing proper materials to be selected and analyzing the root cause of failure. The experimental setup helps to test a crankshaft and its specimen as per ASTM testing procedures and the results are correlated with numerical analysis using ANSYS software. The objective of this investigation is to provide insights through failure analysis to the designers and manufacturers, thereby improve the reliability and safety of automotive crankshafts, ensure safe operation of the vehicle, and eventually minimize financial losses.

Mechanical testing and comparison of porcine tissue, silicones and 3D-printed materials for cardiovascular phantoms.

Background: Cardiovascular phantoms for patient education, pre-operative planning, surgical training, haemodynamic simulation, and device testing may help improve patient care. However, currently used materials may have different mechanical properties compared to biological tissue. Methods/Aim: The aim of this study was to investigate the mechanical properties of 3D-printing and silicone materials in comparison to biological cardiovascular tissues. Uniaxial cyclic tension testing was performed using dumbbell samples from porcine tissue (aorta, pulmonary artery, right and left ventricle). Flexible testing materials included 15 silicone (mixtures) and three 3D-printing materials. The modulus of elasticity was calculated for different deformation ranges. Results: The modulus of elasticity (0%-60%) for the aorta ranged from 0.16 to 0.18N/mm2, for the pulmonary artery from 0.07 to 0.09N/mm2, and for the right ventricle as well as the left ventricle short-axis from 0.1 to 0.16N/mm2. For silicones the range of modulus of elasticity was 0.02-1.16N/mm2, and for the 3D-printed materials from 0.85 to 1.02N/mm2. The stress-strain curves of all tissues showed a non-linear behaviour in the cyclic tensile testing, with a distinct toe region, followed by exponential strain hardening behaviour towards the peak elongation. The vessel samples showed a more linear behaviour comparted to myocardial samples. The silicones and 3D printing materials exhibited near-linearity at higher strain ranges, with a decrease in stiffness following the initial deformation. All samples showed a deviation between the loading and unloading curves (hysteresis), and a reduction in peak force over the first few cycles (adaptation effect) at constant deformation. Conclusion: The modulus of elasticity of silicone mixtures is more in agreement to porcine cardiovascular tissues than 3D-printed materials. All synthetic materials showed an almost linear behaviour in the mechanical testing compared to the non-linear behaviour of the biological tissues, probably due to fibre recruitment mechanism in the latter.

Technologies and materials for repair, restoration and restoration of historical and cultural monuments

Objective. The task has been set to develop materials and technologies for repair, restoration and restoration of cultural heritage objects (CHOs) - historical and cultural monuments of CHOs that meet the requirements.Method. The work uses modern methods of physical and mechanical testing of materials and structures, including destructive and non-destructive quality control methods, as well as a modern mathematical apparatus for generalizing and processing experimental and statistical data.Result. Due to the fact that the South of Russia is rich in cultural heritage, and a significant number of historical and cultural monuments have been destroyed as a result of natural and man-made impacts, special attention is paid to the scientific substantiation and development of technological and technical solutions aimed at improving the efficiency of their repair, restoration and restoration.Conclusion. The work has developed methodological and methodological foundations for organizing work, a scale for assessing damage and destruction of historical and cultural monuments, and repair and restoration compositions based on air and hydraulic lime binders that meet the repair and restoration requirements.

Composites Based on Biodegradable Polymers and Layered Structures

The paper presents the results of mechanical and electrical tests of composite materials based on biodegradable polymers (polyvinyl alcohol, polyacrylamide, starch) and synthetic layered double hydroxides (Ni–Al, Zn–Al) obtained by two-stage (chemical) and one-stage (plasma chemical) methods. The one-stage method for producing composites involves the formation of filler structures during the burning of low-temperature plasma in the bulk of an aqueous polymer solution. Electrode materials were used as precursors. Regardless of the production method, 2D hexagonal structures are formed and embedded in the polymer matrix. This is evidenced by IR spectroscopy data showing shifts in the main characteristic bands and the appearance of new ones. It has been established that layered fillers can be both plasticizers and reinforcing agents. The influence of the viscosity of the polymer matrix on the mechanical characteristics of the composites has been revealed. The introduction of fillers changes the surface roughness, leading to an increase in hydrophobicity of the composites. It has been established that the current–voltage curves of the composites are nonlinear, so that such composites can be considered as flexible analogues of nonlinear electronic components.

Determination of the shaping behavior of thermoplastic composite materials required for simulation of thermoforming

The shaping of composite consolidated plates into products is a complex process. To obtain a defect-free product, we have to bear in mind that thermoplastics reinforced with a fabric practically do not stretch, and their shaping behavior is determined by the mechanisms of shear deformations within a layer or between layers, by the processes of sliding a composite over the surface of tooling and by the flexural rigidity of the consolidated plates. Due to the complex behavior of the material during deformation, the optimization of the thermoforming process by trial and error is rather expensive in implementation and can be successfully replaced by a preliminary simulation. The available software packages intended for modeling the thermoforming process which provide construction of a correct model of the material consistent with the reality, require the introduction of input parameters for the drape of the consolidated plate, its flexural stiffness, the coefficient of friction between layers and with tooling. However, until now there are no standards for their measurement, which significantly hinders the process of modeling the thermoforming of products from consolidated plates based on thermoplastic binders. We present experimental data on the determination of some physical and mechanical properties of carbon fiber reinforced plastics based on polypropylene PP01030, including tensile-displacement tests of the sample, tests with a moving frame that provide evaluating the shear behavior of thermoplastic composite materials, as well as tests for determining the interlayer friction and friction of a composite with tooling. The tests were carried out at the melting temperature of the matrix using specialized tooling, made taking into account the experience of foreign research groups in physical and mechanical testing of thermoplastic composite materials. A method for determining the flexural rigidity of thermoplastic carbon fiber reinforced plastics is proposed. The presented tooling does not require the application of a complex force, and needs only standard tensile test clamps of the testing machine. The data obtained from the physicomechanical tests can be used in virtual modeling of the thermoforming process of consolidated composite plates.

Design of experiments for the calibration of history-dependent models via deep reinforcement learning and an enhanced Kalman filter

Experimental data are often costly to obtain, which makes it difficult to calibrate complex models. For many models an experimental design that produces the best calibration given a limited experimental budget is not obvious. This paper introduces a deep reinforcement learning (RL) algorithm for design of experiments that maximizes the information gain measured by Kullback–Leibler divergence obtained via the Kalman filter (KF). This combination enables experimental design for rapid online experiments where manual trial-and-error is not feasible in the high-dimensional parametric design space. We formulate possible configurations of experiments as a decision tree and a Markov decision process, where a finite choice of actions is available at each incremental step. Once an action is taken, a variety of measurements are used to update the state of the experiment. This new data leads to a Bayesian update of the parameters by the KF, which is used to enhance the state representation. In contrast to the Nash–Sutcliffe efficiency index, which requires additional sampling to test hypotheses for forward predictions, the KF can lower the cost of experiments by directly estimating the values of new data acquired through additional actions. In this work our applications focus on mechanical testing of materials. Numerical experiments with complex, history-dependent models are used to verify the implementation and benchmark the performance of the RL-designed experiments.

Determination of cohesion and friction angle of a MgO-C refractory at room and elevated temperatures

The use of constitutive models in thermomechanical finite element modelling of refractory linings requires knowing the temperature-dependent material parameters. The mechanical testing of carbon-containing refractory materials at elevated temperatures necessitates the protection of samples from oxidation. Therefore, the test concept of the modified shear test (MST) was further developed and a setup was designed to protect the carbon-containing materials from oxidation. A carbon-containing magnesia refractory (MgO–C), which is usually applied in secondary metallurgy for steel ladle refractory linings, was selected as the material of interest. The setup allows the determination of cohesion and friction angle of MgO–C refractories under reducing conditions at temperatures up to 1500 °C. The procedure allows a material parameters determination from uniaxial loading. While coked and as-delivered samples showed different behaviours, a significantly higher cohesion was noted in the as-delivered material. The results showed that the cohesion is highly temperature-dependent, whereas the friction angle remains nearly unaffected.

Compact System for Monitoring Acoustic Emission Parameters in Mechanical Testing of Materials

Compact System for Monitoring Acoustic Emission Parameters in Mechanical Testing of Materials