Test Methods For Materials Research Articles

Problematic issues in the development of norms for masonry structures

Introduction. In recent years, important connections between the regulatory documents on masonry structures, which were based on a system established many years ago, have been destroyed.Aim. To identify the key issues and to outline approaches to their solution. This primarily concerns the inconsistency of State Standards on brick and mortar testing methods, as well as codes of practice for the design of masonry structures.Results. It is shown that the strength of brick and mortar are conditional values, which depend largely on the methods of their testing, shape and size of specimens, exposure conditions prior to testing. In SP 15.13330.2012 “Masonry and reinforced masonry structures”, which is an updated version of SNiP II-22-81*, the design resistance of masonry brick and mortar grades were assigned according to the results of tests in accordance with the State Standards in force at that time. In order to restore connections with State Standards, revisions concerning the design resistance of masonry structures were introduced in SP 15.13330. This was a compromise solution. An optimal solution would be to complement the State Standard for plastic molding bricks with transition coefficients from the strength of polished bricks to the strength of bricks with a mortar-levelled surface. The types of specimens in the State Standard for masonry testing in the form of walls are borrowed from European norms. Testing walls along with columns without taking the scale factor into account leads to incorrect results.Conclusions. Violation of the connections between State Standards for material testing methods and codes of practice for design occurs largely due to lobbying by material manufacturers, who seek to achieve the greatest benefit for themselves. Sometimes there is an unreasonable desire to interfere in the process of developing codes of practice. On the other hand, the development of high-quality regulatory documents is impossible without the involvement of a broader professional community, taking the interests of all parties into account. However, the balance of interests must not translate into the reduction of reliability of buildings and structures under construction.

Апробация методики сдвиговых испытаний геосинтетического композита «КАПЛАМ»

Purpose: to investigate the effect of different test methods on the shear properties of geomaterials and to determine the test method that provides the most consistent shear strength results. Demonstrate the need to include shear test methods for geosynthetic materials in state standards. Determination of interaction properties of geosynthetic composite “KAPLAM” with soil. Methods: a 300×375 mm shear machine was used to perform shear tests at the soil-geomaterial interface with normal loads ranging from 100 to 500 kPa. These tests were performed according to the American standard ASTM D5321. Results: the relationships obtained from the tests allow the identification of the test methodology that produces the most significant shear strength results and an understanding of the fundamental mechanisms underlying the observed shear strength. The need for further investigation of this methodology on other geosynthetics is identified. Practical relevance: overall, these results have important implications for the design of railway embankment slopes, ISDS lining systems and shear strength testing. The tests provide better modelling of field conditions and a more accurate representation of the shear strength of composite materials.

Penetrative fracture behavior of monolayer graphene oxide: nanoscale experiment and molecular dynamics simulation

Abstract Graphene, a two-dimensional material, is expected to be employed as a next-generation component for structural and functional applications because of its light weight and excellent mechanical properties. For applications requiring lightness and impact resistance, preventing penetrative damage upon particle impact is critical for applications in mechanical protection. However, graphene is known to have high defect sensitivity. Graphene oxide (GO) may be a better candidate, as functional groups (e.g., hydroxy and epoxy groups) bonded to the C–C network in GO result in better deformability, ductility, and durability compared to graphene. For mechanical applications, it is crucial to understand the fracture behavior, especially the penetrative fracture behavior, of GO membranes. This study characterizes the penetration behavior and fracture morphology of GO membranes subjected to particle impact. Nanoscale experiments were conducted using an atomic force microscope and laser-induced particle impact test for GO. These material testing methods employ nanoscale spheres to induce particle penetration, with the former experiment conducted under quasi-static loading and the latter under dynamic loading. Additionally, molecular dynamics simulations were performed to elucidate the fracture mechanisms of GO. Finally, cyclic fatigue experiments and simulations revealed that GO’s ductility provides resistance to catastrophic failure, indicating its durability. These comprehensive investigations provide valuable insights into the fracture properties of GO membranes under impact penetration.

Study of hydrogen embrittlement in steels using modified pressurized disks

The integration of hydrogen into natural gas pipelines presents challenges due to Hydrogen Embrittlement (HE), requiring critical material selection and testing methods. One such test is the Disk Pressure Test (DPT), which consists in pressurizing a clamped disk to failure. However, failure happens often at the clamping zone, making analysis difficult. This study aims to develop new disk geometries to control failure location while maintaining the test setup. Using two steel grades (a vintage X52 pipeline steel and a modern E355 modified steel with potential for pipeline use), new disk geometries were tested under helium and hydrogen at various pressure rise rates. Results show successful displacement of failure away from the clamping zones, demonstrating the effectiveness of the new geometries. Hydrogen embrittlement is demonstrated by comparing failure pressures under helium and hydrogen at various pressure rise rates. Using both material testing and simulation, this study provides insights into hydrogen embrittlement.

Microstructure and properties of underwater in-situ wire-based laser additive manufactured duplex stainless steel

ABSTRACT A novel underwater in-situ wire-based laser additive manufacturing (ULAM) technology is proposed for the in-service repair of underwater components in nuclear power plant. Duplex stainless steel (DSS) obtained in air and underwater environments were analysed using material characterisation and testing methods. The effects of underwater additive environments on the microstructure evolution, mechanical properties and corrosion resistance of the specimens were investigated. The results show that the laser heat input is consumed to balance the heat loss of the water-cooled base material during the underwater laser additive manufacturing process, leading to a reduction in the heat input to the molten pool. Underwater specimen exhibit a two-phase balance, with small ferrite grain boundary angles, resulting in better tensile strength and corrosion resistance. Laser reheat treatment leads to a phase change in microstructure, which can enhance the microhardness and the tensile strength. The ULAM system can meet the requirements of actual engineering for cladding layer.

Automated Identification of Outgassed Chemical Species Using Mass Spectrometry for Scientific Space Missions

Current and planned space exploration and life detection missions such as NASA Jet Propulsion Laboratory’s Mars 2020, Mars Sample Return, and Europa Clipper require record-low contamination levels. In this work, we develop a novel automated outgassing contamination species identification method using mass spectrometry data. Thanks to the existing knowledge of ASTM-E1559 and direct analysis in real-time mass spectrometry material testing methods, we improved species outgassing deconvolution and physical characterization techniques. We developed a brand-new combined approach that leverages both tests’ complementary insights into contaminants’ chemical identities. Namely, we rely on the Dromey–Foyster algorithm and the Seven Golden Rules of mass spectrometry analysis to narrow down the probable identified molecules by a factor of 10 compared to the sole use of ASTM-E1559. Furthermore, thanks to recent advances in machine learning spectral analysis, we developed a composite spectral score that ranks all candidate contaminants based on their similarity to the measurements. Ultimately, we validated an automated species identification algorithm on samples of NuSil CV4-2946, Dacron, and a spacecraft cable component. The techniques established in this work enable accurate estimations of outgassed contaminant species’ chemical structure, leading to a comprehensive understanding of the effects of outgassing on scientific objectives.

Digital Resources Construction and Education Research for the Course of Material Research and Testing Methods

The course of Materials Research and Testing Methods aims to help students master the skills of testing and analyzing the composition, structure, property and performance of materials. To improve the teaching quality of this course and help the students understand well about the content, we introduced the distinctive teaching methods such as applying case teaching, developing virtual simulation software and database of cutting-edge instruments, carrying out instrument training, building platform of instrument popularization and national first-class course, guiding research projects and scientific competitions. Therefore, the course has its own distinctive materials that are collected to build the digital resources. How the teaching quality of this course improved by these methods will also be discussed. Furthermore, the construction of the digital resources can help students realize the new learning mode of learning at any time, flexible learning and long-term learning, broadening the channels and ways for students to study the course.

Synthesis and Catalytic Performance of Mo2C/MoS2 Composite Heterojunction Catalysts.

Hydrogen, as a clean, safe, and efficient energy carrier, is one of the hot energy sources that have attracted much attention. Mo2C, due to the introduction of C atoms, makes the atomic spacing of the Mo lattice decrease and changes the width of the d-band, which makes the electronic properties of Mo2C similar to that of Pt noble metals, exhibiting excellent electrochemical hydrogen precipitation performance. MoS2, due to its special crystal structure and tunable electronic structure, has been widely studied. In this paper, Mo2C nanoparticles were prepared by high-temperature carbonization, and then two-dimensional layered MoS2 were be loaded on Mo2C nanoparticles by the hydrothermal method to synthesize Mo2C/MoS2 composite catalysts. Their electrochemical hydrogen precipitation (HER) performance under acidic conditions was tested. The above catalysts were also characterized by modern material testing methods such as XRD, SEM, TEM, and XPS. The results showed that the composite catalysts exhibited the most excellent electrochemical hydrogen precipitation performance at Mo2C/MoS2-3, with the lowest overpotential at a current density of 10 mA cm-2, Tafel slope, and electrochemical impedance. At the same time, the electrochemically active area was dramatically enhanced, with good stability under prolonged testing. The catalytic activity was significantly improved compared with that of Mo2C and MoS2. The characterization and experimental results indicate that the heterogeneous structure of Mo2C and MoS2 formed a built-in electric field between the two, which accelerated the electron transfer efficiency and provided more active sites. The Mo2C/MoS2 composite catalyst is a low-cost, easy-to-prepare, and high-efficiency electrochemical hydrogen precipitation catalyst, providing a new idea for developing green and clean energy.

Material corrosion characteristics of heat-treated SLM-ed Hastelloy X in electrochemical machining process

Selective laser melting (SLM) technology and electrochemical machining (ECM) offer new methods for producing nickel-based superalloys with complex structures and high surface quality, including Hastelloy X parts. However, SLM-fabricated parts exhibit significant anisotropy, and there are no effective criteria for evaluating material corrosion characteristics in actual ECM due to the detachment of research and application, making the parameter selection challenging in actual ECM. To address this issue, this article proposes a comprehensive evaluation system based on the corrosion characteristics in the actual machining process and investigates the effect of heat treatment temperature on the corrosion characteristics of Hastelloy X in ECM. The results show that at a heat treatment temperature of 1000°C, machining efficiency, accuracy, and localization can all be achieved at a good level with good consistency in different directions at the expense of a certain machining accuracy. The 800℃ heat-treated specimen exhibits strong corrosion resistance, providing a significant advantage in machining localization and accuracy. When the heat treatment temperature exceeds the solid solution temperature (more than 1175℃), the mechanical properties and corrosion characteristics of the specimen are significantly degraded. The results of various material testing methods, including electrochemical testing, EBSD, XRD, and EDS indicate that changes in grain size due to recrystallization and the galvanic effect of precipitates are the primary causes of these changes.

Phase coherence factor-based ultrasonic annular array testing method for coarse-grained materials

Metal materials with coarse-grained structures have the characteristics of coarse grain, acoustic anisotropy, and structural inhomogeneity. When the ultrasonic wave propagates in its interior, the above characteristics will cause strong waveform distortion, acoustic energy attenuation, and structural-acoustic scattering, resulting in a poor signal-to-noise ratio of the ultrasonic echo signal. The annular array ultrasonic transducer has a three-dimensional axisymmetric acoustic field, which is less affected by the grain structure than the linear array ultrasonic transducer. It can realize the focus within the detection range by the total focusing method (TFM) post-processing in the way of the full matrix capture (FMC) and is suitable for ultrasonic non-destructive testing of coarse-grained materials with high acoustic attenuation. In this paper, a TFM C-scan testing method based on the phase coherence factor (PCF) denoising is proposed. The C-scan imaging results of the coarse-grained GH4169 specimen verify the denoising effectiveness of the proposed method. Compared with the TFM of the annular array, the PCF can improve the signal-to-noise ratio of the flat bottom hole defect by up to 14.99 dB.

Modeling and prediction of tribological properties of copper/aluminum-graphite self-lubricating composites using machine learning algorithms

The tribological properties of self-lubricating composites are influenced by many variables and complex mechanisms. Data-driven methods, including machine learning (ML) algorithms, can yield a better comprehensive understanding of complex problems under the influence of multiple parameters, typically for how tribological performances and material properties correlate. Correlation of friction coefficients and wear rates of copper/aluminum-graphite (Cu/Al-graphite) self-lubricating composites with their inherent material properties (composition, lubricant content, particle size, processing process, and interfacial bonding strength) and the variables related to the testing method (normal load, sliding speed, and sliding distance) were analyzed using traditional approaches, followed by modeling and prediction of tribological properties through five different ML algorithms, namely support vector machine (SVM), K-Nearest neighbor (KNN), random forest (RF), eXtreme gradient boosting (XGBoost), and least-squares boosting (LSBoost), based on the tribology experimental data. Results demonstrated that ML models could satisfactorily predict friction coefficient and wear rate from the material properties and testing method variables data. Herein, the LSBoost model based on the integrated learning algorithm presented the best prediction performance for friction coefficients and wear rates, with R2 of 0.9219 and 0.9243, respectively. Feature importance analysis also revealed that the content of graphite and the hardness of the matrix have the greatest influence on the friction coefficients, and the normal load, the content of graphite, and the hardness of the matrix influence the wear rates the most.

Experimental research on mechanical, material, and metallurgical properties of Inconel 600: Application in elevated temperature environment

Experimental research on mechanical, material, and metallurgical properties of Inconel 600: Application in elevated temperature environment

Review of Nondestructive Testing Methods for Aerospace Composite Materials

Composite structures and materials have seen significant advancements in cost-effectiveness, product efficiency, and specific properties, leading to their extensive use in the aerospace industry. Reliable nondestructive testing (NDT) of composites is crucial for reducing maintenance costs and addressing safety concerns. This review provides a comprehensive analysis of various NDT methods, including Ultrasonic Testing, Acoustic Emission, Eddy Current Testing, Shearographic Testing, Infra-Red Thermography, and X-Ray Radiography. Each method’s principles, instruments, and applications for defect detection and damage evaluation in composite materials are thoroughly examined. The paper highlights the strengths and limitations of these NDT techniques, emphasizing their roles in ensuring the structural integrity of aerospace composites. Ultrasonic Testing and Infra-Red Thermography are identified as flexible and cost-effective solutions, widely applied in both academic research and industrial sectors. Despite the challenges in providing a complete diagnostic of structural integrity, each NDT method offers unique advantages. Future research in NDT for composites will focus on integrating advanced data processing techniques, such as machine learning and deep learning, and developing smart inspection systems with high precision and rapid data processing capabilities.

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.

Hardness Test Analysis on ST 37 Steel Plate Material and Aluminum Using the Brinell Test Method

One of the most frequently used methods of material testing is hardness testing. The aim of conducting research on material hardness is to determine the hardness value of the material specimens tested, namely ST 37 steel plate and aluminum plate. The test method is to use the Brinell hardness test where the values ​​obtained during testing are from the force load, indenter diameter and pressure trace diameter and the pressure time that has been determined. By using testing tools such as hardness tester, mechanical caliper, indenter, flat file, stopwatch. And the materials used are ST 37 steel plate, aluminum plate and sandpaper. From the test results obtained we can calculate the Brinell hardness value of the test material. The value from the calculation of test data where the highest hardness value using the Brinell method (BHN) for ST 37 steel plate material is 256.992. Meanwhile, the highest hardness value using the Brinell method (BHN) for aluminum plate material is 55,182.

Study on biaxial bending fatigue performance of Engineered Cementitious Composites (ECC)

Structural components such as bridge deck, highway pavement and thin-walled roof dome often are subjected to the biaxial and even multi-axis stress state due to the external load. Also, the fatigue effect cannot be ignored due to the moving vehicle load in the design of these structures. If engineering cementitious composites (ECC) is used in the above traditional concrete structures, their performance, such as easy cracking and short service life can be greatly improved. However, the biaxial bending fatigue performance of ECC should be analyzed in detail. At present, the biaxial bending test methods of cement-based materials include biaxial bending test (BFT) and centrally loaded round panel test (RPT). This study used both RPT and BFT test methods to analyze the biaxial fatigue performance of ECC and used four-point bending test (4PBT) uniaxial fatigue test as a reference. The stress levels S were set as 0.5, 0.6 and 0.7. The uniaxial and biaxial bending fatigue failure procedures of ECC were analyzed by plotting the three-stage deflection development curve, the fatigue damage and strain relationship curve based on the linear cumulative fatigue damage theory, and the S–N curve. The fatigue life of ECC biaxial bending specimens was greater than that of uniaxial bending specimens. At S = 0.5, the fatigue life: BFT > RPT. At S = 0.6, the fatigue life of BFT and RPT specimens was close. At S = 0.7, the fatigue life: BFT < RPT. With increasing stress level, the fatigue life of BFT specimen decreases more than that of RPT specimen. The lognormal distribution model and Weibull distribution model were used to fit the uniaxial and biaxial bending fatigue life of ECC, respsectively. Using the double logarithmic fatigue equation, fatigue life under the failure probability PF of 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 was derived. The survival rate represents the level of safety reservation, which could provide reference and basis for the design of ECC bridge deck and highway pavement with different safety reservation requirements.

BAZI MEKANIKSEL DERI VE TEKSTIL STANDART METOTLARININ UYGULAMALI OLARAK KARŞILAŞTIRILMASI

Fabrics, leathers and artificial materials show structurally different properties. For example, if a fabric material is woven, it is formed by connecting the threads at a right angle to each other with a certain system; on the other hand, leather is formed by naturally binding complex collagen fibers with specific and different angles depending on their area. Also, artificial materials are produced disparately using PVC and PU. These structural differences directly affect the mechanical properties of materials and therefore Turkish Standards Institute (TSE) offers different test methods for textile and leather materials. There are some differences between these standards according to the shape/size of test samples, jaw length, speed, etc. Since leather is an expensive material and has a limited area, sample sizes of leather standards are smaller than the dimensions specified in the textile standard; however, sample sizes in textile standards can be a problem for some expensive textile materials e.g., silk, silver-added fabrics, vicuna, etc. The aim of this study is to examine the differences between the results obtained from the textile and leather standard methods. In this scope, the tensile strength, elongation and tear load values of the two different tanned garment leathers, artificial material, and two different kinds of woven fabrics were obtained by applying both leather and textile standard methods. While there was a statistical difference between the two methods in tensile strength and elongation values for all materials, no difference was observed in tear load values.

The small punch test: An overview of previous research

The knowledge of material properties is a key factor in designing structures which withstand the challenges of their lifetime. Small Punch (SP) test is a material testing method which has the advantage of lean material usage. In this study, an overview is presented on the SP testing method. The aim of this paper is to help researchers by collecting articles about different research fields of SP testing. With the experiences from previous research a promising theme is proposed for future analysis in connection with SP testing.

Characterization Specifications for FRP Pultruded Materials: From Constituents to Pultruded Profiles

Pultruded FRP composites have emerged as a promising alternative to traditional materials like concrete, steel, and timber, especially in corrosive environmental conditions. However, the unique properties of these composites necessitate careful consideration during their implementation, as they differ significantly from conventional materials. Proper testing and characterization of FRP pultruded materials is key for their efficient and safe implementation. However, the existing specifications are not unified, resulting in ambiguity among stakeholders. This paper aims to bridge this gap by thoroughly reviewing current destructive and non-destructive test methods for FRP pultruded materials, specifications, quality control, and health monitoring of FRP structures. Each subsection is further divided into subtopics, providing a comprehensive overview of the subject. By shedding light on these crucial aspects, this article aims to accelerate the adoption and utilization of these innovative materials in practical applications.

On the development of a high strain-rate tensile testing method for thin low-impedance materials

This work deals with the high strain-rate characterization of paper under uniaxial tension using a Split Hopkinson test bench. An aluminum bar system featuring a highly sensitive hollow transmission bar was used. Paper tests were performed in a strain-rate range between approximately 60 s−1 and 210 s−1. The experimental tests showed that the breaking strength appears to decrease with increasing strain-rate. To verify these results, a digital twin of both the paper specimen and the entire test rig was created in an explicit Finite Element method environment. The numerical model was then used to perform a parameter study with different types of transmission bars. It was shown that the system is quite sensitive to additional masses caused by the specimen fixtures, as well as to drastic reductions in the cross section of the transmission bar. As a result, the transmitted measuring signal can be distorted and may need to be corrected using the digital twin.