Test Methods For Materials Research Articles

Applicability of non-destructive laser ultrasound and non-linear ultrasonic technique for evaluation of thermally aged CF8 duplex stainless steel

Duplex stainless steel is a structural material that is highly used in nuclear power plants, especially in the reactor core components and pipelines. Long-term exposure of duplex stainless steel in a high-temperature working environment will cause thermal aging embrittlement. Material deterioration will affect the long-term reliability of nuclear power plants. In this work, we used two different ultrasonic techniques, namely Laser Ultrasound Technique (LUT) and Non-linear Ultrasonic Technique (NUT) for measuring the material properties. The LUT has unique advantages such of being non-contact, non-destructive, and remotely operable, while NUT has considerable measurement sensitivity to the microstructure changes of materials. Therefore, this research mainly focused on duplex stainless steel after the heat aging treatment. The changes in the material properties of the duplex stainless steel after the heat aging treatment were investigated by ultrasonic testing and traditional material testing methods. The results of this study show that the thermal aging with higher duration, the ferrite phase decomposes into Cr-rich αˊ-phase and Fe-rich α-phase. The hardness of both the austenite iron phase and the ferrite iron phase increase with the increase in heat aging time. The phase velocity of duplex stainless steel increases significantly up to a heat aging of 2400 h, and then the phase velocity decreases significantly. After thermal aging treatment at different times, the non-linear factor did not change significantly due to the hardness changes. The non-linear response caused by the heat aging treatment of duplex stainless steel is minimum.

Experimental analysis of orthotropic strength properties of non-crimp fabric based composites for automotive leaf spring applications

We investigated the feasibility of a transversely isotropic approach to assess the strength properties during the design of a composite leaf spring. A modified Arcan test setup was developed to test the strength properties of the used non-crimp fabric based material in all orthotropic directions. Through comparisons with standardized coupon test methods for fiber-reinforced materials, a notch stress factor for tensile and shear load was derived. Our results indicate that fabric influences the material’s strength, and the assumption of transverse isotropy behavior is invalid. The measured transverse tensile strength was lower by a factor of 2.2 in the out-of-plane direction than in the in-plane direction, possibly leading to a lower resistance of leaf springs against delamination. Process induced differences did not significantly affect the measured strength in the tested directions. These findings will be useful in developing leaf springs with increased fatigue resistance.

Proposal of a pure bending test method for advanced composite materials

This paper proposes a simple and precise pure bending test method for composite materials. With CFRP as the subject, we compare conventional bending test methods and extract issues for each of them. Based on the results, we propose a test method that can solve the complexities of the conventional pure bending test method and can also accurately measure the characteristics of the pure bending property. The proposed test method is simpler than the conventional ones and agrees well with the theoretical values.

Antiviral Testing Method for Non-porous Materials

Antiviral Testing Method for Non-porous Materials

Novel Bending Test Method for Polymer Railway Sleeper Materials.

Alternative sleeper technologies have been developed to address the significant need for the replacement of deteriorating timber railway sleepers. The review of the literature indicates that the railway sleepers might fail while in service, despite passing the evaluation tests of the current composite sleeper standards which indicated that these tests do not represent in situ sleeper on ballast. In this research, a new five-point bending test is developed to evaluate the flexural behaviour of timber replacement sleeper technologies supported by ballast. Due to the simplicity, acceptance level of evaluation accuracy and the lack of in-service behaviour of alternative sleepers, this new testing method is justified with the bending behaviour according to the Beam on Elastic Foundation theory. Three timber replacement sleeper technologies—plastic, synthetic composites and low-profile prestressed concrete sleepers in addition to timber sleepers—were tested under service loading condition to evaluate the suitability of the new test method. To address the differences in the bending of the sleepers due to their different modulus of elasticities, the most appropriate material for the middle support was also determined. Analytical equations of the bending moments with and without middle support settlement were also developed. The results showed that the five-point static bending test could induce the positive and negative bending moments experienced by railway sleepers under a train wheel load. It was also found that with the proposed testing spans, steel-EPDM rubber is the most suitable configuration for low bending modulus sleepers such as plastic, steel-neoprene for medium modulus polymer sleepers and steel-steel for very high modulus sleepers such as concrete. Finally, the proposed bending moment equations can precisely predict the flexural behaviour of alternative sleepers under the five-point bending test.

Applicability of Procedural Variants in Ultrasonic Testing

Abstract Ultrasonic testing (UT) is essentially the transmission of high-frequency (0.25…20 MHz) sound waves (mechanical vibration and energy) into a material, in order to interact with the macro-structural constituents of the material which reflect and/or weaken it. Ultrasonic testing – as one of the most common nondestructive material testing (NDT) methods – thanks to its many variants, is able to operate in a mobilized and highly automated fashion; it can be performed on most material types; high accuracy and reproducibility can be achieved in error detection, and it is generally enough if only one side is accessible; changes in elevation can also be verified with this method besides distance measurement, and it is also suitable for determining certain material characteristics. The present article reviews the application technology characteristic of the procedural variants.

Digital Image Correlation of Tensile Properties for Monel 400/SS 316L Dissimilar Metal Welding Joints.

Dissimilar metal weld joints of Monel 400 and Stainless Steel 316L stainless steel were carried out using Gas Tungsten Arc Welding (GTAW). Conventional annealing and cryogenic treatment were performed on the welded joints. Weld joints of this combination of materials have enormous potential applications in power industry and the available related literature is limited. In the present study, the tensile properties of heat treated (HT), cryotreated (CT), and untreated (UT) specimens were studied. The engineering stress and strain were determined experimentally as per Standard Test Methods for Tension Testing of Metallic Materials (ASTM E8). The strain distribution was evaluated at different zones of weld joint was evaluated using Digital Image Correlation (DIC). Significant difference was noticed between the zones. Weld zone of all samples had less local stress and strain and SS 316L heat affected zone (HAZ) zone had more local stress and strain when compared to other zones. The local strain distribution along distance from weld center line and local stress-strain curves of different zones are also predicted. Scanning Electron Microscopy was used to analyze the fracture behavior of welded samples for HT, CT, and UT specimens.

A method to quantify stiffness across the entire surface of a shoe‘s midsole

Quantifying the midsole material characteristics of athletic footwear is a standard task in footwear research and development. Current material testing protocols primarily focus on the determination of cushioning properties of the heel region or the quantification of the midsole properties as one assembly. However, midsoles possess different spatial material properties that have not been quantified from previous methodologies. Therefore, new material testing methods are required to quantify the local material response of athletic footwear. We developed a cyclical force-controlled material testing protocol for the determination of non-homogeneously distributed material stiffness with a high spatial resolution. In five prototype shoes varying in their stiffness distribution, we found that the material properties can be reliably measured across the midsole. Furthermore, we observed a characteristic non-linear material response regardless of the midsole location. We found that the material stiffness increased with an increase of the applied force and that this effect is further intensified by higher testing cycles. Additionally, the obtained midsole stiffness depends on the geometry of the midsole. We explored different approaches to reduce the measurement time of the testing protocol and found that the number of measurements can be reduced by 70% using 2 D-interpolation procedures. Determining the spatial material properties of midsoles needs to be considered to understand foot-shoe interactions. Furthermore, this measurement protocol can be used for quality control within the footwear and can be adapted for considering the effects of different running styles or speeds on ground force application characteristics.

Resistive loss considerations in the finite element analysis of eddy current attenuation in anisotropic conductive composites

The penetration depth of eddy current is widely recognized as a guide in the nondestructive testing (NDT) methods using eddy current, which is often treated as equivalent to the skin effect depth. This paper takes the resistive loss of eddy current into account, and clearly points out the discrepancy between the two terms, especially in the case of carbon fiber reinforced plastic (CFRP) composites, which are less conductive and show strong anisotropy. Based on the theoretical modeling of skin depth and resistive loss according to Poynting's theorem, this paper adopts finite element numerical simulation to study the attenuation characteristics of current density and magnetic field strength under the conditions of different conductivity, frequency and anisotropy ratio. In addition, a set of experiments are conducted to verify the simulation results semi-quantitatively. The results show that the resistive loss dominates the eddy current attenuation in less conductive and high anisotropic composites, resulting in a frequency independent attenuation law, which is very different from skin effect. Meanwhile, the resistive loss in the orthotropic laminate is greatly reduced due to the existence of the interface between the adjacent layers. This research provides a theoretical basis for the realization of high frequency eddy current testing method for anisotropic CFRP composite materials.

Study on mechanical properties testing of highway concrete pavement construction machinery materials

In order to solve the problems of large error and long time-consuming in the traditional mechanical property test methods, a new mechanical property test method for highway concrete pavement construction machinery materials is proposed. The relationship between the deformation component and the displacement component of the microstructure of the concrete pavement in the equilibrium coordinate system is obtained. The limit value of the critical thickness of the construction material of the highway concrete pavement is obtained by the second derivative function. Based on the analysis principle of AFM force curve, the relationship between mechanical materials and elastic modulus of highway concrete pavement construction is determined, and the performance analysis of highway concrete pavement construction mechanical materials is realised. The test results show that the error of mechanical properties analysis of highway concrete pavement construction machinery materials by the proposed method is only 0.3%, and the test time is short.

Secondary Wave Method for Polymer Composite Defect Diagnostics by the Radio Wave Method

The issues of using the combined radio wave and thermal methods for nondestructive testing of polymer composite materials in laboratory and factory conditions are considered.

Experimental Investigation of the Effect of Heat Flux on the Fire Behavior of Engineered Wood Samples

This paper presents the experimental study results on the effect of heat flux emitted by a standard source on the charring and ignition characteristics of wood construction materials (plywood, chipboard, and oriented strand board) using infrared thermography (IRT) in the narrow spectral ranges of infrared wavelength. The time to ignition (TTI), charring rate and depth were obtained for the samples. In addition, the effect of several fire retardants on the charring rate and depth of the samples and TTI was analyzed. All fire retardants contribute to an increase in TTI, which confirms their main function—fire protection. However, the effect of fire retardants differs noticeably depending on the material. A new experimental technique is suggested, with the infrared imaging of the temperature distribution along the end of a sample under the heat flux effect on its frontal surface. The uniqueness of this approach consists in the registration of the entire process of ignition and combustion of the presented materials, which occurs in real time without contact with high spatial and temporal resolution. Using the infrared camera of the research class, it becomes possible to record the entire process from the occurrence of the temperature exposure region to the deep carbonized crater in the body of the material. The results can serve as additional recommendations in the development of fire hazard testing methods for construction materials and fire retardants.

Application of Mycelium-Bound Composite Materials in Construction Industry: A Short Review

Mycelium-bound composite materials are a new class of sustainable and affordable biocomposites that have been recently introduced into packaging, fashion, and architecture as alternative to traditional synthetic materials. In recent years extensive investigation and research studies have been dedicated to explore methods of production and processing as well as to find potential applications for mycelium-bound composite materials. However, application of this novel biocomposite within the construction industry has been limited to only small-scale prototypes and exhibition installations. The problems with low mechanical properties, high water absorption and lack of standard methods for production and testing of mycelium-bound composite materials remain as main challenges that need to be addressed when used as non-structural or semi-structural elements. This short review aims to display the potential of mycelium-bound composite materials for their use within the construction sector in the form of thermal and acoustic insulation as well as replacement for drywalls and tiles. This review summarizes the main available information with regards to the properties of mycelium-bound composites that have been used in construction sector while suggesting the direction for the future research and development on these biocomposites for their applications within the construction industry.

Using damage evaluation to assess the fatigue behaviour of cement-treated base material from laboratory and full-scale performance tests

Cement-treated base (CTB) has become the most popular cement-modified road-base material. This study theoretically connects understandings of CTB damage behaviour derived from laboratory and full-scale experiments using the continuum damage mechanics approach. Fatigue-life tests using four-point bending testing were performed on laboratory CTB specimens and compared to test data from full-scale fatigue testing conducted by the Australia Road Research Board. Damage evolution curves developed from both test environments were characterised and compared, resulting in three key findings: (1) damage evaluation through the normalisation technique can be reasonably used to overcome the inherently different conditions of the testing environment; (2) a significant distinction was observed in the final phase of the damage evolution curves; (3) damage evolution of field CTB can be reasonably predicted by the damage evolution of laboratory CTB specimens. Future research should investigate the effects of parent material gradation, testing method, and unforeseen factors to the damage characteristics of CTB.

Develop Creative Brick Kiln Cultural Products by Powder Metallurgy Process Technique

Brick is one of the most common traditional building materials in the world. Located at the foot of the Bagua Mountain in Changhua, Taiwan, Qiaotou community residents make good use of mountain clay to develop the brick kiln industry, and once created a glorious history. With the increase in building materials regulations, the chimneys of brick kilns no longer smoke, and the industry has gradually declined. This study hopes that the traditional brick kiln industry will be improved through technological technique and input a new generation of innovative thinking. The general brick kiln cultural products will be re-granted to new life from the decline and showing the creative thinking in the local culture. The materials test method was used to study the processing technology of brick powder. It is expected to improve the precision of brick products and reduce the production cost through the application of the powder metallurgy process technique. And applied to the brick creative culture product design to create unique merchandise.

WITHDRAWN: Self-healing composites: A review on material characterization and testing methods

This article has been withdrawn at the request of the author(s) and/or editor. The Publisher apologizes for any inconvenience this may cause.The full Elsevier Policy on Article Withdrawal can be found at https://www.elsevier.com/about/our-business/policies/article-withdrawal.

Study on the safety grade identification and reinforcement effect of factory structure building

The quality of construction projects is related to the safety of people's lives and property, and also has a greater impact on the stability of the entire society; factory structure is one of the most common productive buildings, and some factory buildings have been partially lost its using function due to a long service history; in order to ensure the safety, applicability and durability of these factory buildings and continue to utilize or strengthen these factory structures, it is necessary to perform safety testing and identification for factory buildings at the first time. Structural safety assessment is the process of inspecting, measuring, analyzing and evaluating the structural effects, structural resistance and their interrelationships and finally obtaining structural safety grade of buildings that have been built or in service for many years. On the basis of summarizing and analyzing previous research works, this article expounded the research background, current status and future challenges of building safety grade identification, elaborated material testing methods, specifications, frameworks and processes of security grade identification for factory structure buildings, analyzed the concrete strength and steel corrosion detection, structural seismic identification and bearing capacity calculation of factory building, and proposed corresponding reinforcement measures and discussed its reinforcement effect. The final identification results of an engineering case are in good agreement with its actual construction conditions and on-site inspections and basically satisfactory the results of the factory building structure. The study results of this paper provide a reference for the further researches on the safety grade identification and reinforcement effect of the factory structure building.

Comparison of CT and metallographic method for evaluation of microporosities of dye cast aluminum parts

Nowdays, the different material characterisation and testing methods are constantly evolving. With modern techniques, we have the ability to take a look inside the product without sample cutting, with modern CT systems. The modern techniques with their development become closer and closer to industrial applications. However, the testing protocols are sometimes 1 or 2 steps behind. This is mostly due to the cost or the complexness of the new testing methods. In this study we would like to take a quick look on the current standard industrial testing of porosities and microcracks and compare them with computer tomograph assisted testing.

Effect of specimen gauge reduction on uniaxial tension properties of reinforcing steel

The Standard Test Methods for Tension Testing of Metallic Materials (ASTM E8) mandates a specimen gauge reduction for obtaining the tensile properties of reinforcing steel bars. The standard outlines the specimen preparation requirements and methods to ensure that test results well represent the material properties. On the other hand, some codes differ regarding the approach to specimen preparation. They do not apply gauging, for both deformed and plain steel bars. Thus, the effect of specimen gauge reduction on the tensile properties of reinforcing steel bars was evaluated, and the interconnection of properties to the layer hardness was analysed. The experiment governed a range of deformed hot-rolled bar sizes, tested in tension using precision instruments. The Rockwell hardness test was implemented layerwise on the specimen’s cross section, and the hardness number (HRC) was measured as a function of the layer distance to the centre. A finite element model was constructed to study the stress concentrations induced by a constant indentation, simulating the HRCs, and to numerically construct the stress–strain relationship of ungauged steel bars based on the core properties and the section HRC relationship. Scanning electron microscopy readings were performed to visually and chemically justify the results. It was shown that the specimen gauge reduction significantly influenced the resulting stress–strain behaviour of the material, and the yield and ultimate strengths were reduced. It was also demonstrated that the hardness response is proportional to the distance to the specimen’s axes. The corresponding yield and ultimate strengths thus increased accordingly, from the inner to the outer layers of the bar. Testing a gauged specimen will therefore result in lower strength than that of an ungauged steel bar.

Experimental Mechanics Procedures for Applied Stress Analysis on U-bend Stainless Steel 304 by using Strain Gauges Technique

The industrial failed pressure vessel leakage was operating in various parameters such as temperature, pressure, grain size, applied stresses, residual stresses, stress discontinuities in pressure vessel nozzle and many more directly or indirectly factors which lead to stress corrosion cracking (SCC) case study. Laboratory experimental steps are shown in this research to roughly determine the applied stresses, although it is very difficult to find out the exact way to calculate the actual true stress and true strain applied on a bending austenitic stainless steel (SS) 304 during the pressure vessels fabrication process. The effect of strain rate method was used to calculate the external applied stress on SS 304 plate as per E8 standard test methods for tension testing of metallic materials. The stress-strain behavior of SS 304 plate on bending test as per the recommended practice for hot-rolled and cold-finished steel bars in accordance with Table A1.2 ASTM A 370-15 standard test methods and definitions for mechanical testing of steel products was investigated in the laboratory. The investigation was carried to evaluate the external applied stresses on 13 mm thickness of U-bend SS 304 plate. Strain gauges were used on U-bend samples to determine the external stress induced on bending SS 304 plate. The findings from this study suggest that, we should minimize the mechanical tensile stress concentrations due to both elongation and compression during the fabrication, welding and installation process which occurs at sharp edges and notches. Stress safety factor boundary imposed by the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel code,Section VIII, Division 1, Part UG-23 maximum allowable stress value, and also the design and fabrication criteria should be followed by the engineers especially for the oil and gas industrial pressure vessels fabrications.