Advanced Testing Techniques Research Articles

Inspection of aluminum sheets using a multi-element eddy current sensor: 2d and 3d imaging of surface defects of various sizes and internal defects at various depths

In the industrial sector, ensuring reliability and durability is of paramount importance. Our research aims to advance beyond conventional non-destructive testing methods by focusing on thorough defect detection and imaging. We utilize advanced, sensor-enhanced eddy current testing, featuring multiple elements arranged in a cutting-edge serial array. This innovative configuration addresses the issue of magnetic repulsion between sensor elements, thereby speeding up the testing process and ensuring precise results through both 3D and 2D imaging. This sophisticated approach allows us to more effectively characterize defects of varying sizes and depths in aluminum sheets. By meticulously collecting and analyzing data from the sensors, we can identify the appearance and nature of these defects with greater clarity. Our findings introduce a pioneering method for defect detection, highlighting the efficacy of our advanced testing technique. Our research underscores the potential of multi-element eddy current sensors in revolutionizing the inspection process. The ability to produce detailed 3D and 2D images of surface and internal defects represents a significant leap forward in non-destructive testing. This comprehensive imaging capability not only accelerates the detection process but also enhances the accuracy and reliability of defect characterization. By employing this state-of-the-art technology, we can detect even the smallest and most deeply embedded defects that traditional methods might miss. The precise imaging provided by our approach ensures that defects of various sizes and depths are accurately identified and characterized. This level of detail is crucial for maintaining the structural integrity and performance of aluminum sheets used in industrial applications. Our research demonstrates a groundbreaking approach to defect detection in aluminum sheets, leveraging the advanced capabilities of multi-element eddy current sensors. The innovative use of a serial array of sensors, combined with sophisticated data analysis techniques, allows for rapid, accurate, and detailed imaging of defects. These findings pave the way for improved reliability and durability in industrial applications, setting a new standard for non-destructive testing.

Advancements in integrated robotic sensing: A European perspective

Robotic Non-destructive Testing and Sensing stands at the forefront of technological innovation, offering capabilities in assessing structural integrity, safety, and material quality across diverse industries. This comprehensive review article provides a detailed exploration of the field, focusing on the substantial contributions of European researchers and institutions. The need for non-destructive testing has been a constant in industries that rely on structural integrity, including aerospace, manufacturing, energy, construction, and healthcare. Traditional testing methods, such as radiography, ultrasonic testing, magnetic particle testing, and dye penetrant testing, have been integral for quality control and safety assurance. However, the robotisation of such methods has marked a profound shift, enabling precise, fast, efficient, and repeatable testing while minimising human exposure to hazardous environments. European researchers and institutions have played an instrumental role in driving the evolution of integrated robotic sensing. The historical perspective of the field reveals the pioneering spirit of Europe, as collaborative initiatives led to the development of robotic platforms equipped with advanced sensors and testing techniques. A critical aspect of the European impact on robotic inspection applications lies in developing advanced sensors, innovative robotic platforms, novel robotic path-planning and control approaches and data collection and visualisation tools. These developments continue to influence the global landscape of robotic sensing. European researchers remain at the forefront of current trends and innovations as the field continues to evolve. This review article will delve into these recent advancements, highlighting Europe’s pivotal role in pushing the boundaries of technology and application. The implications and applications of robotic sensing reverberate across multiple sectors worldwide. From inspecting critical aerospace components to ensuring the quality of manufactured goods, these technologies underpin safety and quality standards.

Advancements in integrated robotic sensing: A European perspective.

Robotic Non-destructive Testing and Sensing stands at the forefront of technological innovation, offering capabilities in assessing structural integrity, safety, and material quality across diverse industries. This comprehensive review article provides a detailed exploration of the field, focusing on the substantial contributions of European researchers and institutions. The need for non-destructive testing has been a constant in industries that rely on structural integrity, including aerospace, manufacturing, energy, construction, and healthcare. Traditional testing methods, such as radiography, ultrasonic testing, magnetic particle testing, and dye penetrant testing, have been integral for quality control and safety assurance. However, the robotisation of such methods has marked a profound shift, enabling precise, fast, efficient, and repeatable testing while minimising human exposure to hazardous environments. European researchers and institutions have played an instrumental role in driving the evolution of integrated robotic sensing. The historical perspective of the field reveals the pioneering spirit of Europe, as collaborative initiatives led to the development of robotic platforms equipped with advanced sensors and testing techniques. A critical aspect of the European impact on robotic inspection applications lies in developing advanced sensors, innovative robotic platforms, novel robotic path-planning and control approaches and data collection and visualisation tools. These developments continue to influence the global landscape of robotic sensing. European researchers remain at the forefront of current trends and innovations as the field continues to evolve. This review article will delve into these recent advancements, highlighting Europe's pivotal role in pushing the boundaries of technology and application. The implications and applications of robotic sensing reverberate across multiple sectors worldwide. From inspecting critical aerospace components to ensuring the quality of manufactured goods, these technologies underpin safety and quality standards.

Long Term Evolution of MEA for AEM

Green hydrogen technology, aimed at revolutionizing clean hydrogen production, has recently garnered significant attention. However, the pursuit of cost-effective methods for obtaining clean hydrogen remains a substantial challenge for various industries. Anion exchange membrane water electrolysis (AEMWE) has emerged as a promising solution, leveraging low-cost materials and high efficiency, thus attracting extensive interest from both researchers and industries. Yet, the adoption of AEMWE faces two major hurdles: its relative immaturity as a technology and the limited exploration of its durability and stability. Within the Production, Use, and Storage of Hydrogen (PUSH) Research Center, a collaborative effort involving Chalmers Technical University, Lund University, Umeå University, and Research Institutes of Sweden (RISE), we are dedicated to addressing the scientific and technical barriers currently hindering the seamless integration of hydrogen into sustainable energy systems. Our comprehensive research strategy encompasses every facet of hydrogen, including production, storage, distribution, and utilization, all working synergistically in harmony. One of the ongoing projects in this research center, conducted in cooperation with RISE, around enhancing the durability of components and devices through advanced testing techniques applied to AEMWE. This study present the results of a 2000-hour lifetime test and Accelerated Stress Testing (AST) conducted on a commercial Membrane Electrode Assembly (MEA), showcasing the system's remarkable stability. It must be mentioned that in the next step, these results will be compared with lifetime test and AST from MEAs from other partners within PUSH Research Center.

Development and Functional Validation Method of the Scenario-in-the-Loop Simulation Control Model Using Co-Simulation Techniques

With the facilitated development of highly automated driving functions and automated vehicles, the need for advanced testing techniques also arose. With a near-infinite number of potential traffic scenarios, vehicles have to drive an increased number of test kilometers during development, which would be very difficult to achieve with currently utilized conventional testing methods. State-of-the-Art testing technologies such as Vehicle-in-the-Loop (ViL) or Scenario-in-the-Loop (SciL) can provide a long-term solution; however, validation of these complex systems should also be addressed. ViL and SciL technologies provide real-time control and measurement with multiple participants; however, they require enormous computational capacity and low-latency communication to provide comparable results with real-world testing. 5G (fifth-generation wireless) communication and Edge computing can aid in fulfilling these needs, although appropriate implementation should also be tested. In the current paper, a realized control model based on the SciL architecture was presented that was developed with real-world testing data and validated utilizing co-simulation and digital twin techniques. The model was established in Simcenter Prescan© connected to MATLAB Simulink® and validated using IPG CarMaker®, which was used to feed the simulation with the necessary input data to replace the real-world testing data. The aim of the current paper was to introduce steps of the development process, to present the results of the validation procedure, and to provide an outlook of potential future implementations into the state of the art in proving ground ecosystems.

Challenging diagnoses of tetraploidy/diploidy and trisomy 12: utility of first-tier prenatal testing methods.

Introduction: Chromosome mosaicism and low-grade mosaicism present a challenge for diagnosis in the era of SNP array and NGS. Tetraploidy is a rare numerical chromosomal abnormality characterized by the presence of four copies of each chromosome. The prevalence of tetraploidy/diploidy mosaicism cases is extremely rare in the human population. Accurate estimates of the frequency of this chromosomal anomaly are lacking due to its classification as an extremely rare and difficult-to-detect condition. Methods: In this report, we describe two cases involving challenging diagnoses of tetraploidy/diploidy and trisomy 12. We utilized advanced genetic testing techniques, including SNP array, to examine the chromosomal abnormalities in these cases. We compared the results from SNP array to conventional G band karyotyping to assess the utility of first-tier prenatal testing methods. Results:Our analysis revealed two cases of tetraploidy/diploidy and trisomy 12 with atypical presentations. SNP array analysis provided higher resolution and more precise information about the chromosomal anomalies in these cases compared to conventional G band karyotyping. Additionally, the prevalence of tetraploidy/diploidy mosaicism was confirmed to be extremely rare in the population. Discussion: Low-level mosaicism is difficult to diagnose, and in many cases, it has traditionally been identified through techniques such as G band karyotype or FISH. Microarray has become an invaluable diagnostic tool for detecting chromosomal abnormalities, offering high-resolution insights. However, it may not always be able to detect rare occurrences of tetraploidy or tetraploidy/diploidy mosaicism. As a result, it is recommended to perform a G band karyotype analysis after obtaining a negative microarray result before considering other diagnostic methods with a potentially higher yield of diagnosis. For the detection of low-level mosaicism, combined diagnostic methods should be considered. The diagnosis of mosaicism is a multistep process that can be time-consuming, often requiring the application of more than one diagnostic technique. This approach is crucial for accurate diagnosis and comprehensive patient care. Further research is warranted to better understand the underlying mechanisms of these rare chromosomal anomalies and to develop more effective diagnostic strategies for challenging cases.

Fabrication of carbon dots@2D CuCo-MOF composites as lubricating additives in pentaerythritol ester for enhanced tribological properties at elevated temperatures

In this study, we successfully synthesized CD@CuCo-MOF composites, which are composed of ultrathin two-dimensional (2D) nanosheets of metal-organic framework (MOF) doped with carbon dots (CDs). The synthesis process involved hydrothermal and ultrasonically assisted self-assembly with a proper solvent ratio. The composites were then dispersed into pentaerythritol ester (PETE) with the aid of ultrasonic treatment. We thoroughly evaluated the physicochemical features and tribological properties of the CD@CuCo-MOF composites using advanced testing and characterization techniques including XRD, Raman, FTIR, TG, XPS, FIB-TEM and so on. The results demonstrated that the addition of CD@CuCo-MOF resulted in a 61.1 % reduction in the coefficient of friction (COF) at a concentration of 0.1 wt% when compared to the base oil at room temperature. With the rise in temperature, CD@CuCo-MOF exhibited excellent lubricating properties due to its hybrid inorganic-organic structure and interlayer sliding effect. This led to a reduction of 59.2 % and 42.9 % in the mean COF compared to PETE oil at temperatures of 100 °C and 200 °C. This enhancement in the tribological performance of CD@CuCo-MOF could be attributed to several factors, including its superior dispersion stability, excellent lubricating properties, and involvement in the formation of a tribofilm. The tribofilm formed from a combination of CDs, CuCo-MOF, metal oxides, carbides, and nitrides promoted the rearrangement of the contact surface, thereby minimizing the friction and wear between the rubbing surfaces. These findings hold significant guiding implications for advancing the development of potential-controlled lubrication using MOFs doped with CDs across a wide temperature range.

How Do Impurities in Electrolytes Affect the Electrochemical Performance of Oxides in Lithium-Ion Batteries?

The recovery and treatment of spent LIBs has already been studied extensively. On one hand, the hydrometallurgical recovery of cathode materials has aroused widespread attention because of its low energy consumption and benefit to the environment. On another hand, the purification of the materials reclaimed from spent batteries is a challenging process with high probability that, later, some remaining impurities such as transition metal carbonates and sulfates could be released into the electrolyte. In this way the impurity content will have a serious impact on the final performance of the battery. To this point different electrochemical and analytical measurements were conducted to elucidate the effects of impurities in the electrolyte formulation, specifically Li, Mn, Co, Ni, and Al carbonates, sulfates, and acetates. The base LP30 electrolyte was intentionally contaminated with a maximum concentration of selected impurity to study the effects of the contaminated electrolyte on the electrode. Different combinations and varieties were explored correspondingly. Test setups were based on both, NMC811 in half cells (vs. Li) and symmetrical Li||Li cells, and the influence of contaminations was thus exploited on the Li counter electrode and on the NMC811 in Li||NMC811 configuration. A number of standard and advanced electrochemical test techniques such as CC-CV, electrochemical impedance, rate capability tests, GITT, and CV was applied for a fully understanding of the electrochemical characteristics of standard cathode active materials such as NMC811 when electrolytes with (artificially downgraded) low purity levels are present. The presentation will focus on discussion of results regarding the presence of transition metals Ni, Co, and Mn as impurities in the electrolyte which showed a significant impact on the electrochemical performance of the tested cells. When the concentration of the impurities increases, both the overpotentials at the cathode and the rate of capacity decay during cycling increase as well. The data shown will be very helpful for the researchers to understand the impact of impurities on the performance of oxide-based LIB cathode materials.

Ice Core Methane Analytical Techniques, Chronology and Concentration History Changes: A Review

Ice cores are invaluable in paleoclimate research, offering unique insights into the evolution of the natural environment, human activities, and Earth’s climate system. Methane (CH4) is a crucial greenhouse gas, second only to CO2 in its contribution to global warming, and is one of the primary anthropogenic greenhouse gases. Understanding historical CH4 concentration changes is essential for predicting future trends and informing climate change mitigation strategies. By analyzing gas components trapped in ice core bubbles, we can directly examine the composition of ancient atmospheres. However, there are relatively few comprehensive reviews on ice core CH4 testing techniques, chronology, and concentration history records. In response to this gap, our paper systematically reviews ice core CH4 analytical techniques, chronology, and concentration history changes. Our review indicates that current research on CH4 in non-polar ice cores is insufficient compared to polar ice cores, facing challenges such as high data dispersion, outlier frequency, and the presence of non-atmospheric signals. These limitations hinder our in-depth understanding of CH4 signals in non-polar ice cores, and the reliability of atmospheric CH4 concentration changes they reflect. To address these challenges, we propose exploring and applying advanced testing techniques, such as Continuous Flow Analysis technology, in non-polar ice cores. Additionally, we emphasize the research gap in utilizing CH4 records for age determination in ice core chronology. Future research should focus on this area to advance our understanding of ice core chronology and the history of atmospheric CH4 changes in non-polar regions, ultimately contributing to more effective climate change mitigation efforts.

Study on properties of representative ordinary Portland cement: Heavy metal risk assessment, leaching release kinetics and hydration coupling mechanism

As an important basic material in the construction industry, the potential harm of heavy metal elements contained in Portland cement (PC) to the ecosystem and human health cannot be ignored. In this research, PC from five representative areas of China was chosen to systematically research its heavy metal risk assessment, leaching release kinetics and hydration coupling mechanism using the advanced scientific testing techniques and research methods, so as to provide reasonable suggestions for the efficient, safe and environmentally friendly utilization of PC. The research indicated that the chemicalconstituents of PC are CaO, SiO2, Al2O3, Fe2O3, etc. The primary mineral composition were calcite, quartz, magnesite and mullite. Through the detection and analysis of the contents of Cr, As, Cd and Pb in PC, in accordance with the analysis results of environmental evaluation model, there were no obvious environmental risks of the four heavy metals, but the contents of Cr and Cd in PC need to focus on. At the same time, Cr in PC needs to be key-point controlled as human health risk assessments indicated that they posed a carcinogenic risk to the human body through oral administration. However, as the cumulative effect of As and Pb, their toxicity cannot be ignored in human health evaluation. Therefore, As and Pb need to be re-incorporated into the category of characteristic noxious heavy metals. But the control level was marked as medium; Cr and Cd control level was high.The fitting results of release kinetics showed that most of the heavy metal leaching in PC can be well fitted by Elovich model and second-order kinetic model. This indicated that Elovich model, second-order kinetic model and parabolic model were more worthy of study in the leaching release kinetics of heavy metals. In the meantime, the study showed that the leaching of heavy metals in PC was controlled by a series of effects such as parabolic model. On the basis of the dynamic model of heavy metal content in five kinds of PC with curing duration, the optimum safe age of noxious heavy metals in PC after PC hydration was explored. Through XPS test results, it was discovered that the Cr, As, Cd and Pb in PC present in the formation of Cr3+, Cr6+, As3+, As5+, Cd2+ and Pb4+. These noxious heavy metal ions were harmful to the human body by means of the infiltration and migration of soil and groundwater. Lastly, the hydration coupling mechanism of heavy metals in PC were discussed, and the content of characteristic heavy metals in PC under various usage scenes were limited.

Fabrication of Novel Polymer Composites from Leather Waste Fibers and Recycled Poly(Ethylene-Vinyl-Acetate) for Value-Added Products

This investigation was focused on evaluating the utilization of Leather-waste, i.e., “Leather Shavings”, to develop “Poly(ethylene-vinyl-acetate)” (EVA) based “polymer matrix composites”. Composites with the highest ratio of 1:1 were developed using a rolling-mill, which was then subjected to hot-press molding for value-added applications, notably in the “floor-covering”, “structural”, “footwear”, and “transportation domain”. The specimens were examined for evaluating the “physico-mechanical characteristics” such as, “Compressive and Tensile, strength, Abrasion-resistance, Density, tear-resistance, hardness, adhesion-strength, compression, and resilience, damping, and water absorption” as per standard advanced testing techniques. Raising the leather-fiber fraction in the composites culminated in considerable enhancement in “physico-mechanical characteristics” including “modulus”, and a decline in “tensile-strain” at “fracture-breakage”. The thermo-analytic methods, viz. TGA and DSC studies have evidenced that substantial enhancement of thermo-stability (up to 211.1–213.81 °C) has been observed in the newly developed PMCs. Additionally, the DSC study showed that solid leather fibers lose water at an endothermic transition temperature of around 100 °C, are thermo-stable at around 211 degrees centigrade, and begin to degrade at 332.56-degree centigrade for neat recycled EVA samples and begin to degrade collagen at 318.47-degree centigrade for “leather shavings/recycled EVA polymer composite samples”, respectively. Additionally, the “glass transition temperature” (Tg) of the manufactured composites was determined to be between −16 and 30 °C. Furthermore, SEM and EDAX analysis have been used to investigate the morphological characteristics of the developed composites. Micrograph outcomes have confirmed the excellent “uniformity, compatibility, stability and better-bonding” of leather-fibers within the base matrix. Additionally, the “Attenuated-total-reflection” (ATR-FTIR) was carried out to test the “physicochemical chemical-bonding”, “molecular-structure”, and “functional-groups” of the “base matrix”, and its “composites” further affirm the “recycled EVA matrix” contained additives remain within the polymeric-matrix. An “X-ray diffraction study” was also conducted to identify the “chemical-constituents” or “phases” involved throughout the “crystal-structures” of the base matrix and PMCs. Additionally, AFM analysis has also been utilized to explore the “interfacial adhesion properties” of mechanically tested specimens of fabricated polymeric composite surfaces, their “surface topography mapping”, and “phase-imaging analysis” of polymer composites that have leather-shavings fibers.

Coverage-directed Differential Testing of X.509 Certificate Validation in SSL/TLS Implementations

Secure Sockets Layer (SSL) and Transport Security (TLS) are two secure protocols for creating secure connections over the Internet. X.509 certificate validation is important for security and needs to be performed before an SSL/TLS connection is established. Some advanced testing techniques, such as frankencert , have revealed, through randomly mutating Internet accessible certificates, that there exist unexpected, sometimes critical, validation differences among different SSL/TLS implementations. Despite these efforts, X.509 certificate validation still needs to be thoroughly tested as this work shows. This article tackles this challenge by proposing transcert , a coverage-directed technique to much more effectively test real-world certificate validation code. Our core insight is to (1) leverage easily accessible Internet certificates as seed certificates and (2) use code coverage to direct certificate mutation toward generating a set of diverse certificates. The generated certificates are then used to reveal discrepancies, thus potential flaws, among different certificate validation implementations. We implement transcert and evaluate it against frankencert , NEZHA , and RFCcert (three advanced fuzzing techniques) on five widely used SSL/TLS implementations. The evaluation results clearly show the strengths of transcert : During 10,000 iterations, transcert reveals 71 unique validation differences, 12×, 1.4×, and 7× as many as those revealed by frankencert , NEZHA , and RFCcert , respectively; it also supplements RFCcert in conformance testing of the SSL/TLS implementations against 120 validation rules, 85 of which are exclusively covered by transcert -generated certificates. We identify 17 root causes of validation differences, all of which have been confirmed and 11 have never been reported previously. The transcert -generated X.509 certificates also reveal that the primary goal of certificate chain validation is stated ambiguously in the widely adopted public key infrastructure standard RFC 5280.

Advanced tensile testing as a new tool to quantify properties of food

Mechanical properties of food products are regularly analysed by tensile tests. The aim of this study was to demonstrate the potential of using advanced tensile testing techniques to better understand the mechanical properties of anisotropic food products, such as meat analogues and certain dairy products. The effects of various tensile testing parameters, including tensile gauge length and deformation rate, on the interpretation of mechanical properties of meat analogues was studied. Additionally, digital image correlation, an image analysis technique, was used for true distance recording and analysis of fracturing behaviour of the products. An isotropic product was prepared from solely soy protein isolate, and an anisotropic product was prepared from soy protein isolate and pectin using the shear cell technology. The tensile properties of the products were studied with four different moulds with varying gauge lengths of 17.5, 15, 11.5, and 8.5 mm, and at three deformation rates of 46.2, 23.1, and 11.6 mm/min. A smaller gauge length and slower deformation rate improved visualization and interpretation of the multi-stage descending branch in force – distance curves of anisotropic products. Additionally, tensile parameters, specifically toughness, proved to be more accurate at small gauge length and slow deformation rate, because overestimation due to rapid crack propagation was prevented. True distance data obtained with digital image correlation further improved the interpretation of the fracturing behaviour of the products. Inhomogeneous strain distribution in anisotropic products was shown with digital image correlation, in contrast to the homogeneous strain distribution observed in isotropic products. Furthermore, the Poisson's ratio, obtained through digital image correlation, explained inherent differences in structure and plasticity between isotropic and anisotropic meat analogues. This study shows the importance of careful selection of testing parameters and techniques. Moreover, it advises the use of digital image correlation for better measurement of fracture mechanics and strain distribution.

Decoration of carbon encapsulated nitrogen-rich MoxN with few-layered MoSe2 nanosheets for high-performance sodium-ion storage

Transition metal nitrides have become the focus of research in sodium ion batteries (SIBs) due to their unique metal properties and high theoretical capacity. However, the low actual capacity is still the main bottleneck for their application. Herein, using Mo-aniline frameworks as precursors, the carbon encapsulated nitrogen-rich MoxN is decorated by few-layered MoSe2 nanosheets (MoSe2@MoxN/C-I) after the facile calcinating, selenizing, and nitriding. The carbon encapsulation can effectively strengthen the structural stability of MoxN. The nitrogen-rich MoxN and decoration of few-layered MoSe2 can create rich heterointerfaces and extra active sites for rapid sodium-ion storage, thus promoting reaction kinetics and improving actual capacity. The MoSe2@MoxN/C-I as an anode achieves a large reversible capacity of 522.8 mAh g−1 at 0.1 A g−1, and 254.3 mAh g−1 capacity is obtained after 6000 cycles at 5.0 A g−1, showing signally improved sodium-ion storage properties. The storage mechanisms and kinetic behaviors are described systematically via the advanced testing techniques and density functional theory (DFT) calculations. It is found that the nitrogen-rich MoxN as the substrate is the basis of long cycling stability, and the few-layered MoSe2 are the key to improving actual capacity. This work indicates that the decoration of few-layered selenides has a broad application prospect in high-performance metal-ion batteries.

A Day in the Life of an Oil Laboratory

In this article, the author walks the reader through the challenges of an oil laboratory from receipt of oil samples and storage to analysis and characterization. This first article in the “A day in the life of a __ laboratory” series introduces the entire process from sampling to reporting requirements with references to advanced analytical equipment, testing techniques, and software.

The mechanical behaviour of Bolders Bank till

Advanced sampling and testing techniques are applied to assess the mechanical behaviour of a stiff, silt-and-clay dominate, stony, low plasticity UK till whose genesis and post-depositional history imparted complex profiles of yielding pressures and shear strengths that differ considerably from those of K0 consolidated waterborne sediments. It is shown that the till reaches the limits of its elastic behaviour and undergoes Y1 yielding at very small strains, after which stiffness is nonlinear. Tests reach stable critical state failures at strains exceeding 25%. The Y1 yield surface is kinematic and, once engaged, travels with the effective stress path, as does a second Y2 surface. Stiffnesses vary with mean effective stress raised to fractional exponent ≈0.5. The till displays far more marked sample size dependency and anisotropy in stiffness than in shear strength. It also shows significantly strain-rate dependent behaviour and displays an isotach response. The main features of the till’s shear strength and dilatancy behaviour can be synthesised within a critical state based interpretive framework that brings field and in situ testing outcomes together with laboratory experiments conducted over a wide range of stress levels and overconsolidation ratios, considering both natural and reconstituted specimens.

Cavity expansion analysis of normal indention of rocks with lateral confinement

Indentation of rocks with lateral confinement is strongly related to rock fragmentation in drilling, mechanized tunnelling, and mining. Yet, the interpretation of the results and its transfer to use in practice is complicated by both the limited specimen size and boundary conditions associated with the application of lateral confinement. In this study, a new semi-analytical solution for the problem of a finite-cavity expansion in rock specimens of finite radial extent is present for the analysis of rock indentation with lateral confinement. To account for possible strain hardening/softening effect, an extended linear strain hardening/softening, i.e. constant plastic tangential modulus, Drucker-Prager model with non-associated flow rule is used to describe the stress-strain behavior of rocks. The model predictions, valid up to crack initiation, agree well with experimental observations that peak indentation pressure increases with lateral confinement, indicating that for a correct interpretation of results, the ratio between specimen size and the tip width of a truncated indenter as well as the boundary conditions shall be considered. The results point to the need for further development of the cavity expansion model by incorporating more features to model the realistic rock behavior and for more experimental studies with lateral confinement using advanced testing technique to monitor the failure process.

A deep learning method for damage prognostics of fiber-reinforced composite laminates using acoustic emission

Damage prognostics of fiber-reinforced composites using advanced nondestructive test techniques is of great significance due to their complicated damage mechanisms. This paper employs the acoustic emission (AE) technique to monitor the performance degradation process and to estimate the residual load-bearing abilities of glass fiber/epoxy composite laminates with the damage evolution of various failure modes. Based on the prior knowledge of AE signals, a prognostic model by combining the feature evaluation algorithms and deep learning methods is developed. First, the model conducts the feature evaluation on twenty-four AE features and filters out the degradation-insensitive features from the multiple perspectives of different AE sensors. Second, a convolutional neural network model is built and trained on five informative features for the degradation estimation. The estimation accuracy is validated to be generally high that depends on the degradation stage. Third, the effect of the number of AE signals in an input sequence on the estimation is further investigated. Results show that such a prognostic model provides a feasible path to quantify the degradation process and damage tolerance of composite materials.

In Vivo Blood-Repellent Performance of a Controllable Facile-Generated Superhydrophobic Surface.

Fabrication of a blood-repellent surface is essential for implantable or interventional medical devices to avoid thrombosis which can induce several serious complications. In this research, a novel micropatterned surface was fabricated via a facile and cost-effective method, and then, the in vitro and in vivo blood-repellent performances of the controllable superhydrophobic surface were systematically evaluated. First, a facile and cost-effective strategy was proposed to fabricate a controllable superhydrophobic surface on a medically pure titanium substrate using an ultraviolet laser process, ultrasonic acid treatment, and chemical modification. Second, the superhydrophobicity, durability, stability, and corrosion resistance of the superhydrophobic surface were confirmed with advanced testing techniques, which display a high contact angle, low adhesion to water and blood, and excellent resistant element precipitation. Third, the platelet-rich plasma and whole blood were applied to evaluate the hemocompatibility of the superhydrophobic surface by means of an in vitro experiment, and no blood cell activation or aggregation was observed on the superhydrophobic surface. Finally, hollow tubes with an inner superhydrophobic surface were implanted into the left carotid artery of rabbits for 2 weeks to verify the biocompatibility in vivo. The superhydrophobic surface could effectively eliminate blood cell adhesion and thrombosis. No obvious inflammation or inordinate proliferation was found by histological analysis. This research provides a facile and cost-effective strategy to prepare a blood-repellent surface, which may have promising applications in implanted biomedical devices.

A critical review on wear and corrosion of carbide free bainitic steel

Different research on wear and corrosion of CFB (carbide free bainitic steel) over the past two decades has enabled a better understanding and advanced applications of CFB steel. With the help of advanced testing techniques, and equipment the detailed study of microstructure and nanostructured steels has been possible. The earlier years were focused on comparison of the bainite steel with the steel which is quenched and tempered (QT) for identifying the wear tendencies and comparison between carbon free bainite and martensite for the corrosive behavior of the carbide free bainitic steel. Later the trend shifted towards the nanostructured analysis from microstructure analysis with the improvement in the instruments. Advancements like HT-CAT i.e., high temperature continuous abrasion tester have an important role to play, the mechanism of material removal rate studied. There has also been development in alloying the bainite to reduce the corrosion rate and give more strength. Current trends in the form of study of wear and corrosion of carbide free bainitic steel and future needs are discussed hereby.