Qualification Tests Research Articles

Study of the relationships between microstructure and local mechanical properties in the ductile-to-brittle transition of a bainitic steel containing local segregations

Although considered a 1st-class option to meet the drastic requirements of Reactor Pressure Vessels (RPV) environments, Mn-Mo-Ni bainitic alloys also have segregated microstructures that can lead to heterogeneous mechanical properties. The latter should explain the scatter and the brittle fracture sometimes observed along the ductile-to-brittle transition during qualification tests. The present study focuses on a highly segregated SA 508 Gr.3 (aka 20MND5) steel and investigates the evolutions of local mechanical properties with temperature. Microstructure analysis revealed positive and negative segregations mainly composed of lower and upper bainite, respectively. An experimental device was developed and combined with a systematic procedure to enable local microhardness measurements from room temperature to − 40 °C. Analysis of hardness maps revealed two critical parameters assumed to be involved in the macroscopic brittle fracture as the temperature decreases. The first one is a significant increase in the hardness of both phases, particularly a continuous increase in the lower bainite’s hardness, suggesting that this phase could preferentially lead to brittle fracture. A wide range of hardness values in selected positive segregation reinforced the idea of the possible existence of very local weak points that could explain the dispersion of the results of the macroscopic Charpy test. The second parameter is an extension in the brittle surfaces, leading to a greater probability of testing a brittle area due to an extension surface area of the weak points.

Development and Airworthiness Certification of the Ti6Al4V Inlet Casing Inner Forging

The inlet casing inner has manufactured using Ti-6Al-4V alloy through a closed die-forging route. It undergoes cyclic loads in addition to operating in extreme conditions in high-temperature environments. The demanding mission requirement of these engines necessitates the inlet casing inner to be flawless throughout its life cycle while retaining its structural integrity. It makes the qualification for airworthiness of the casing, a daunting task. In addition, the qualification tests also help to evaluate the design and manufacturing processes (closed die forging) of the inlet casing inner. The tests also provide data for further improvement of the inlet casing inner in terms of strength and fatigue life. It helps to ensure that the inlet casing inner will be able to perform as expected throughout its operational life. All the batch and consolidated test results comply with the relevant ASTM, MIL standards, and test schedule requirements.

Magnetic Screen Effects on Torque Ripple and Efficiency of Dual Air-Gap Surface Permanent Magnet Synchronous Motor

Electric motors with a double air-gap structure offer increased power or torque density compared to their single air-gap counterparts, achievable through double-stator or double-rotor configurations. In a previous study, the authors proposed a double-stator permanent magnet synchronous motor (PMSM) with a magnetic screen placed in the middle of the rotor to isolate the outer and inner motors. However, the analysis of the magnetic screen was not provided in that study, as the design was arbitrarily chosen. This research focuses on the effects of the magnetic screen size and selects the appropriate dimensions for optimal motor performance. Finite element analysis (FEA) is employed to assess the electromagnetic characteristics of the screen. Subsequently, the motor is manufactured and tested. The results show that the chosen magnetic screen size contributes to significant efficiency improvements. In particular, the motor achieved an efficiency of 95.2% during the qualification test, surpassing the efficiency obtained in the previous study.

Impact of neutron irradiation on SiC power MOSFETs after stress tests qualification

The failure of power devices produced by atmospheric neutrons, even at sea level, is a critical issue to assess the reliability of these devices in automotive applications. Usually, accelerated neutron tests are performed to estimate the failure in time (FIT) values of the power devices under different operating conditions, by using virgin device samples. In this work, neutron tests were performed on commercial SiC power MOSFETs which pass HTGB and HTRB qualification tests, commonly used in automotive qualification procedures to verify the gate-oxide and junction and termination integrity. The impact of these reliability qualification tests on the neutron FIT values was investigated.

A comparative analysis of the regulations, codes and standards for on-board high-pressure hydrogen storage cylinders

Hydrogen storage cylinder is an important component in high-pressure gaseous hydrogen (HPGH2) storage system, and plays a key role in hydrogen-powered transportation including land vehicles, ships and aircrafts. Over the past decade, the number of hydrogen fuel cell vehicles (HFCVs) has rapidly increased worldwide. In order to promote the application of hydrogen storage cylinder, guide its design, manufacture, inspection and testing, a series of regulations, codes and standards have been issued. The Chinese national standard, GB/T 42612, for type IV hydrogen storage cylinders has also been issued. This paper first gives a brief overview to these regulations, codes and standards. Furthermore, the specifications including scope, category, filling cycles, service life, materials, design, manufacture, qualification tests and periodic inspections are analyzed and compared. Issues about evaluation method for hydrogen compatibility of non-metallic materials, welded joints of plastic liner, joint between boss and liner are also discussed. Notably, the performance requirements in GB/T 42612 are generally in accordance with the international ones, but the requirements of materials, design and manufacture are more detailed.

A case study into a battery company and their 18650 batteries

When a company's lithium-ion batteries have been found to cause numerous fires, not only the battery quality, but also the company's design, manufacturing, and testing qualifications come into question. Through a case study, this work demonstrates how a widely accessible lithium-ion battery, available in online outlets has defects, lacks sufficient protection mechanisms, and is generally at risk of being unsafe using various non-destructive methods. Company information was collected from the National Enterprise Credit Information Publicity System in China, the United States Patent and Trademark Office, and site visits. Through the investigation, it was found that the company is only a shell company with no design or manufacturing abilities. Based on the analysis, recommendations for the selection of batteries are provided, including supply chain analysis, testing, and teardown characterization.

Preliminary architecture of the DTT remote handling test and training facility

The realization of a specific REMote HAndling Test and Training Facility (REMHAT) is necessary for the development and optimization of the Remote Handling (RH) system, to demonstrate the fulfilment of all its design requirements, for testing and validation of the RH maintenance procedures, for the qualification and acceptance testing of RH equipment and tooling. Furthermore, it provides training and certification to the RH maintenance operators, by making available to operators the knowledge, instructions and experiencing of the Virtual Simulator platform, the control room devices, the robots and tooling to be used for RH tasks. In this work, the preliminary architecture of the DTT REMHAT facility is described, with a focus on the added value of the adoption of Virtual Reality (VR) technologies enabling real-time alignment of virtual robots’ configuration with the real ones (Digital Twin). A first approach to the facility design is proposed, starting from the technical requirements: Environmental, Design, Physical, Functional, Operational, Human Factors and Product assurance and safety. The proposed logical architecture consists of four Sub-Systems (S/S): building and auxiliaries, mock-ups, robots and Control Room. In the present work, a particular attention is paid on the last one. The idea is to create a digital twin of the RH equipment mock-ups to be coupled with software of real-time structural simulation, in order to have at disposition and show in VR environment real-time additional information about the real environment, like robots’ deflections and/or vibrations, clearances and possible collisions detection. These data could be crucial for the operator’s decision-making process about a sudden intervention on the RH system, further to their employment for future studies and optimization. Therefore, for each subsystem of the facility, the components identification and a description of the software and hardware aspects are provided. In conclusion, an overview of the critical issues of such complex system is presented, in order to prepare the ground for future research works.

Design Validation and Reliability Assurance of Electronic Systems Using the Next Generation RGT Models

Arrhenius Accelerated Growth Model (AAGT) is the next generation accelerated testing models used for design validation and reliability assurance of electronics systems. These models are used in design and manufacturing phases towards reliability enhancement of the system respectively. AAGT Models uses Highly Accelerated Stresses for screening of the components towards uncovering Compared to traditional qualification test methods, design flaws, latent defects, component selection problems, and manufacturing flaws can be detected fast. The procedure includes thermal dwells and quick temperature changes while subjecting the test unit to increasing degrees of stress. Dynamic stresses (Pseudo-Random Vibration covering all 6DOF systems) and a combination of thermal and dynamic PSD stresses towards quickly precipitating inherent/hidden defects quickly. These Accelerated models used to qualify modern active array radar modules like Transmit Receive Modules (TRMs) which will be in large numbers and It will be difficult and time-consuming to filter these modules individually using the traditional way. To increase the quality and dependability of electronic devices, much accelerated life tests have been extensively adopted. However, extremely accelerated life tests may only be used as a qualitative approach to assess a product's dependability; they cannot be used to quantify a product's reliability, such as MTBF/MTTF. Consequently, in order to efficiently assess the level of product reliability while improving product reliability in a timely manner. HALT/HASS uses Arrhenius Accelerated Growth Model that is an effective technique used for screening of the module with in short period. This paper discuss in detail with a case study on active array modules deliberating about the test methodology, challenges faced during Using Arrhenius accelerated test models, rapid testing and assessment of these Four channel TRMs used for airborne Fire Control Radar for combat operations.

Design of High Specific Power Solid Oxide Fuel Cells

The development of solid oxide fuel cells (SOFCs) has progressed from the early Electrolyte Supported Cell (ESC) to state-of-the-art Anode Supported Cell (ASC), which allows the implementation of thinner electrolyte layer (less than 10 micron) and reduction in the operating temperature (below 800°C). The various components of SOFC are constantly being optimized by many research groups to further improve the overall stack performance, including specific power, power density, thermal shock resistance, rapid start-up, and thermal cycling exposure.Precision Combustion, Inc. (PCI) has been working on an advanced electrochemical-based energy storage and power generator design for meeting aggressive specific-power and specific-energy targets required for mobile and transportation applications, such as all-electric propulsion of ground and air vehicles. The key drivers are an exceptionally power-dense solid oxide fuel cell design operating with energy-dense liquid fuels and a hybridized system architecture that maximizes component efficiencies for ultra-high system efficiency. This effort builds on PCI’s experience in developing groundbreaking SOFC generators for mobile and space applications.PCI has developed and demonstrated a novel design of fuel cells with high specific power, that also allows for direct internal reforming of methane and hydrocarbon fuels within a SOFC stack. The system consists of interconnected internal reforming Microlith® metal mesh catalysts strategically embedded within the solid oxide stack. The fuel cell configuration was optimized to reduce CTE mismatch and to improve area specific resistance. The resulting enhanced heat transfer design of the combined components offers the potential for higher overall system efficiency and system simplification as well as enables further compactness and weight reduction of the fuel cell while improving the conditions for long system life. The approach also offers the potential to operate with a wide range of input fuels (i.e., high hydrocarbons as well as various levels of CO2 and water in the fuel inlet) without forming carbon. Carbon formation within the stack system has been known to be detrimental to the performance and durability. Our approach allows for the operation of a modular, advanced SOFC stack for generating power directly from hydrocarbon fuels. Computational design, process simulation, and qualification testing were performed to validate the concept.In this presentation, the results from a breadboard SOFC stack system operation will be highlighted, including the power density, efficiency, and durability. An improvement in the performance as a result of the design advancement, which could improve the stack lifetime, will also be described. The carbon avoidance in the stack while operating with hydrocarbon fuels and with a low water requirement was confirmed. Sensitivity study of the concept to temperature, flow rate, and anode fuel composition was performed and will be highlighted. Finally, preliminary results from the fuel cell design optimization activities will be summarized.

Influence of different rainfall patterns and soil water content on hydrological processes in small watersheds

Introduction: Due to climate and underlying surface changes, flash floods occur frequently in northwest China, and the extreme rainstorm weather and flash floods along the eastern foot of Helan Mountain are increasing.Method: By constructing a hydrological model to simulate ten historical mountain flood events in the Suyukou watershed of the eastern foot of Helan Mountain, this study explores the constitutive relationship between rainfall and flood, evaluates accuracy, and analyzes errors. Six characteristic rain patterns were designed based on three parameters representing the position of rainfall peaks and the trend characteristics of rainfall, using 63 actual rainfall processes with a duration of 6 h selected from the rainfall stations of Suyukou watershed. Early warning indicators under different conditions were carried out based on the set of rain patterns.Results: The research results indicate that eight out of the ten simulated floods have passed the qualification test and the simulation results are good. The HEC-HMS hydrological model is suitable for simulating mountain floods in small watersheds and can provide good support for the simulation and early warning of mountain flood disasters.Discussion: Designing a rain pattern set based on actual data has put forward higher requirements for mountain flood warning and forecasting, making the warning more in line with the local actual situation and greatly improving the effectiveness of warning and forecasting.

Based Learning Media Model Website for Making Mood Boards Fashion at Vocational Education Institute

The research was conducted to design a learning media model that can be used online. The method in this study uses a 4D development model, a stage that is carried out only to the development stage. The application used to design learning media is Dreamweaver and then the qualification test is carried out by media experts and material experts and the trial test is done on 35 trainees in training institutions and courses. The resulting learning media model has qualifications in terms of usability, functionality, and visual communications aspects by media experts in highly qualified categories, and the qualification results by material experts in relation to learning design, material content, language, and communications things are obtained in the category Highly qualified, and evaluations by students of the results based on usability aspects in most of these applications are acceptable to students with highly satisfactory answers on components P1 to P10 with highly qualifying categories.

Qualification of a Wankel Rotary Engine for UAV Application - Airworthiness Challenges

An indigenous Wankel Rotary Engine of 40 kW class has been developed for Unmanned Aerial Vehicle (UAV) application. It should be capable of flying flawlessly for long duration at designated altitude and carrying the payload intended for the mission. The engine has to withstand high shock loads during launching from a mobile launcher and has to climb to the designated altitude within a specified time. To meet these requirements the engine needs to deliver required power while operating at its maximum speed during take-off and climb. Therefore qualification of a Wankel rotary engine for this type of application is a great challenge and needs thorough study of its component durability and engine performance and reliability. This paper presents the various qualification tests stipulated on the components, systems and on engine to establish its performance, integrity and reliability. The paper also highlights the basis of clearing the engine for its first flight. Engine made its maiden flight successfully on an UAV platform exhibiting satisfactory performance.

Development of an Active Wingtip for Aeroelastic Control

This paper presents the design of an innovative wingtip device actively actuated to control the aeroelastic loads, with a focus on the gust load alleviation. It summarizes the work carried out in the Clean Sky 2 AIRGREEN2 project, where the device was developed from scratch and reached a relevant technology readiness level with the full-scale prototype manufacturing and testing, compulsory to obtain the permit to fly. This paper describes the overall design of the devices, covering the structure, the aero-servo-elasticity characteristics of the whole aircraft, the actuation system design, the scaled wind tunnel testing, and the full-scale structural qualification tests. The paper proves how the development of a new item involves several disciplines simultaneously, remarking on the importance of an integrated approach to the new generation aircraft design.

Interaction Study of Energetic Protons and Electrons with the Vacuum Ultra Violet Source used in the Complex Irradiation Facility

Context: One important factor to be considered for space missions is the radiation environment. It is composed of energetic particles, such as protons, electrons and ions, and electromagnetic radiation, photons ranging from Vacuum Ultra Violet (VUV) to Far Infrared (FIR). Each of these radiation sources have an unique energy spectrum that further depends on the location inside the solar system, e. g. Earth orbits or interplanetary space.For material qualification and material engineering, individual irradiation is considered and their effects are superimposed. However, effects occurring when two and more radiation types simultaneously are present have barely been investigated yet. Further complexity is added, when additional interactions take place due to laboratory hardware. Aims: This publication reports on the efforts made to analyse and measure the interaction of a VUV and corpuscular radiation sources. The aim is to quantify the deviations due to interactions and conclude consequences for the simultaneous operation of these radiation sources. Methods: In order to quantify the effects, the Complex Irradiation Facility (CIF), located at the DLR Bremen has been used. It connects proton and electron accelerators together with VUV and UV light sources to an ultra high vacuum chamber. The corpuscular and VUV radiation sources have been operated simultaneously. The reaction of the operation parameters, such as current measured with Faraday Cups (FC) has been tracked and post-processed. Results: It has been discovered, that protons considerably interact with the gas mixture used to operate the VUV source. This interaction decreases for higher beam intensities of the corpuscular irradiation. It was found, that this is likely due to protons ionizing gas atoms which are then measured by the FC as current. For electrons, this phenomena was not observed due to their smaller stopping power. The discovery restricts the acceleration factor of the CIF for proton together with VUV irradiation, but does not necessarily limit the range of application of the CIF depending on the requirements of the material and/or qualification test. Energy range of electrons stays unrestricted.

Design and Development of Conical/Contour Nozzle For Slow Burning Solid Booster Operating In Sub-orbital Mission

In order to optimize the performance of the solid booster operating in sub-orbital altitude the contour of the nozzle needs to be tailored. The conventional convergent/divergent nozzle design is either over or under expanding for the altitude of operation. Therefore, minimizing the flow separation and losses is extremely difficult and cumbersome. In this regard, the divergent portion of nozzle plays vital role to attain the maximum performance with suitable design modification. A novel and promising concept of conical and contour nozzle divergent for slow burning propellant motors operating in sub-orbital altitude is designed and being realized for qualification test. Conical and contour nozzle divergent is a viable solution to avoid flow separation during the lower pressure and lower altitude region of the mission. The design arrived as per the mission requirement, has a conical divergent up to 737 mm from throat plane and third order polynomial profile up to exit, which will give a turn back angle of 5°.The injection point of Secondary Injection Thrust Vector Control System (SITVC) of nozzle is chosen at 45% of total distance from throat plane to exit plane. The present study brings out the theretical estimations of a conical/contour nozzle perfromance with a slowest burning solid booster operating at lower altitude, < 35 km. Theoretical Computational Fluid Dynamics (CFD) simulation study is carried out to assess the effect of nozzle profile on the flow transition. The basic design methodology adopted to avoid flow separation and the governing formulations are presented in this paper.

Indigenous Development of Titanium Compressor Blade For Turbofan Engine

The Indigenous development of titanium compressor blade was taken up for turbofan engine for aeronautical applications. This titanium compressor blade is classified as flight safety critical part due to its rotating nature in dynamic load conditions. This blade is made from precision forging in titanium material with strength class of 880-1130 MPa. The material produced in accordance with this specification is melted by the triple VAR process or the cold hearth plus VAR process. The material specification calls for compliance on requirements on a forging lot/heat-treat lot/ingot for metallurgical defects like High Interstitial Defects (HID) "Type I" alpha defects, High-Density Inclusions (HDI), High-alpha defects ("Type II" alpha defect), Beta flecks, Clean shrinkage porosity and Strain-induced porosity. The forging required for compressor blade was developed as per approved test schedule, machined for finished dimensions and assembled and type tested in turbofan engine for its qualification. The titanium compressor blade was cleared for production after successfully completing stipulated qualification requirements. This paper covers the approach toward indigenous development of aero-engine titanium compressor blade forging, machining, assembly and its qualification testing in details

Performance Qualification Testing Improves Processing of Lumened Surgical Instruments in Ultrasonic Cleaners.

The use of performance qualification (PQ) tests for ultrasonic cleaners leads to improvements in the quality of processing lumened surgical instruments. Evidence and national standards assert the need for health care facilities to implement a quality management system related to device reprocessing and testing the adequacy of mechanical cleaning processes. Testing includes showing that ultrasonic cleaners have properly functioning cavitation, soil removal, and lumen perfusion capabilities. This article summarizes survey responses from an audit of sterile processing personnel regarding ultrasonic cleaning units in health care facilities. The article also provides guidance to facilities regarding assessing installation, operational, and PQ related to ultrasonic cleaning equipment. Implementing PQ testing of ultrasonic cleaners in sterile processing units leads to a decreased risk of soiled instrumentation in the OR, which can reduce the risk of patient infection and adverse events.

Nursing education in the age of artificial intelligence powered Chatbots (AI-Chatbots): Are we ready yet?

This article discusses the challenges and implications of artificial intelligence powered chatbot (AI-Chatbots) in nursing education. Chat Generative Pre-trained Transformer (ChatGPT) is an AI-Chatbot that can engage in detailed dialog and pass qualification tests in various fields. It can be applied for drafting course materials and administrative paperwork. Students can use it for personalized self-paced learning. AI-Chatbot technology can be applied in problem-based learning for hands-on practice experiences. There are concerns about over-reliance on the technology, including issues with plagiarism and limiting critical thinking skills. Educators must provide clear guidelines on appropriate use and emphasize the importance of critical thinking and proper citation. Educators must proactively adjust their curricula and pedagogy. AI-Chatbot technology could transform the nursing profession by aiding and streamlining administrative tasks, allowing nurses to focus on patient care. The use of AI-Chatbots to socially assist patients and for therapeutic purposes in mental health shows promise in improving well-being of patients, and potentially easing shortage and burnout for healthcare workers. AI-Chatbots can help nursing students and researchers to overcome technical barriers in nursing informatics, increasing accessibility for individuals without technical background. AI-Chatbot technology has potential in easing tasks for nurses, improving patient care, and enhancing nursing education.

Grain interactions under thermo-mechanical loads investigated with coupled crystal plasticity simulations and high-energy X-ray diffraction microscopy

Nickel (Ni)-based superalloys are used for safety-critical components in the aerospace industry because of their high strength at elevated temperatures. These materials are subjected to complex thermal and mechanical cycling due to service conditions, which leads to thermo-mechanical fatigue (TMF) failure. The failure mechanisms associated with TMF are dependent on microstructural characteristics and loading parameters, such as temperature, strain range, and strain-temperature phasing, requiring a large set of experimental test matrices to study TMF failure. One means to reduce the necessity of extensive and exhaustive testing for material qualification is with model-based approaches. In this work, to study the complexities of micromechanical TMF damage, a temperature-dependent, dislocation density-based crystal plasticity model for a Ni-based superalloy is generated with uncertainty quantification. The capabilities of the model's temperature dependency are examined via direct instantiation and comparison to a high-energy X-ray diffraction microscopy (HEDM) experiment under coupled thermal and mechanical loads. Unique loading states throughout the experiment are investigated with both crystal plasticity predictions and HEDM results to study early indicators of TMF damage mechanisms at the grain scale. Via a crystal plasticity-based failure metric that can predict likely sites for crack initiation, regions of extreme values indicate the spatial location of microstructural damage, while showing correlation with high strain gradients. The results also indicate that the extreme value of thermo-mechanical damage accumulation is influenced by the surrounding grains characteristics including slip system activity, lattice curvature, and neighboring grain compatibility interactions, quantified via a grain interaction strength-to-stiffness ratio orthogonal to the grain boundary.

Validation of a Qualification Procedure Applied to the Verification of Partial Discharge Analysers Used for HVDC or HVAC Networks

The insulation condition of HVDC grids consisting of cable systems, GIS, and converters should be monitored by partial discharge (PD) analysers using artificial intelligence (AI) tools for efficient insulation diagnosis. Although there are many experiences of PD monitoring solutions developed for the supervision of the insulation condition of HVAC grids using PD analysers, there are no standardised requirements for their qualification available yet. The international technical specification TS IEC 62478 provides general rules for PD measurements using electromagnetic methods but does not define performance requirements for qualification tests. HVDC and HVAC PD analysers must be tested by unambiguous test procedures. This paper compiles experiences of using PD analysers with HFCT sensors in HVAC grids (cable systems, GIS, and AIS) to define a qualification procedure for HVAC systems. This procedure is applicable to HVDC grids (cable systems, GIS, AIS, and converters) because the particularities related to the insulation behaviour under HVDC voltage are also considered. Representative PD sources are discussed in HVAC and HVDC positive and negative polarity. The PD pulse trend of representative insulation defects in HVDC cable systems is quite different from that of HVAC grids. Special attention should be paid to the acquisition of PD signals in HVDC grids since few pulses appear in solid insulations, mainly during voltage changes (polarity reversals or surges), but rarely in continuous operation with constant direct voltage. A synthetic PD simulator has been developed to reproduce trains of PD pulses or noise signals, similar to those that can appear in the power network. A set of three functionality tests has been developed for qualification of the diagnostic capabilities of PD analysers working up to 30 MHz addressed to HVDC or HVAC grids: (1) PD recognition test, (2) PD clustering test, and (3) PD location test. This qualification procedure has been validated by means of a round-robin test performed by five research institutes (RISE, FFII, TUDelft, TAU, and UPM) using commercial and in-development AI PD recognition and clustering tools to demonstrate its robustness and applicability. Applying this qualification procedure, two PD methods for electrical detection and prevention of insulation defects have been approved, one for HVAC and the other for HVDC grids.