bluuebunny/crossref_metadata_2025_split huggingface dataset:
Progress of EASICS Validation Experiments and Code Comparison of R5, RCC-MRX and ASME III Division V
Authors: James Peter , Coon David , Austin Colin , Underwood Nicholas , Meek Caroline , Chevalier Marc , Dean David 
Published: October 2021

Abstract
The “Establishing AMR Structural Integrity Codes and Standards for UK GDA” (EASICS) project was established in 2019 to help support the acceptance of Advanced Modular Reactors, or AMRs, which are typically based on high temperature Generation IV reactors. The EASICS project is aiming to provide guidance on the requirements for codes and standards for the design of AMRs for use in the UK, to ensure that state-of-the art knowledge will be brought to bear on developing the required design and assessment methodologies. The EASICS project started in July 2019 and is looking to complete by December 2021.
To support this aim, the work presented in this paper provides an overview of two interacting aspects of the programme. The first is to perform validation tests for high temperature creep-fatigue assessments of a plant relevant component. The second aspect is to use these results, to provide a comparison of internationally recognised approaches for the assessment of high temperature (creep regime) components. This approach will be repeated for two other case scenarios deemed to be plant relevant components. This paper builds upon the initial overview paper presented at the 2020 conference providing an update on progress.
One of the cases presented herein, described as the Thin Walled Welded Pipe Test uses specialist testing of a plant relevant component under high temperature loading conditions is underway with some initial results available. The validation testing includes both fatigue tests and creep-fatigue tests on 316H welded thin section tubes. The tubes have been subjected to strain-controlled tension/compression (R-ratio of −1), with some including a displacement controlled dwell. The tests are being conducted at 525°C. An update to the progress of these tests is included herein.
To help enhance interaction with the code bodies, and to understand the impact of differences in the approaches, comparative assessments have been performed when adopting R5, ASME Section III Div 5 and RCC-MRx. One comparison will be based around the tests detailed above (tube test). A further assessment comparison will consider the Evasion mock-up tests provided by CEA (sodium based thermal shock tests). The third assessment case is loosely based around a plant relevant assessment within one of the UK Advanced Gas Reactors (AGRs). This paper provides an overview of the results from all these cases using R5, ASME Section III Div 5 and RCC-MRx.
The subsequent discussions covers results, differences and potential impact to the codes which will all help to inform a guidance document to support assessing AMRs within a UK regulatory framework.
High Temperature Hydrogen Attack (HTHA) Models for the Petrochemical Industry
Authors: Swindeman Michael , Pavlina Erik J. , Perdomo Jorge 
Published: October 2021

Abstract
Establishing safe operating limits for equipment operating in hydrogen service remains a concern for the petrochemical industry. A methodology to prioritize equipment, inform future inspections, and guide inspection discovery path forward decisions has been in development for the past several years. The approach is multi-tiered and considers the process conditions that lead to risk of damage, the potential extent of damage, and the effect of applied and residual stresses on the rate of damage growth. The key metric for Fe-C steels and Fe-C-0.5Mo steels is the damage index, which is calculated from a damage rate equation that has been calibrated to select laboratory test data and reported HTHA incidents documented in API 941. The damage rate and significance of damage is handled by considering damage as both diffuse (continuum assessment) and localized (crack/flaw assessment). This approach was originally intended as a means for prioritizing inspection. However, once margins are established to account for uncertainties in operating conditions and material variation, so-called time-dependent Nelson curves can be generated for use in design. This paper provides an overview of the HTHA damage modeling technique and results of recent experimental work, including component-level testing used for validation of the model.
Simplified HTHA Evaluation Using Larson Miller Parameter Concepts
Authors: Krishnamurthy Sujay , Hantz Benjamin F. 
Published: October 2021

Abstract
Researchers have been developing mechanistic approaches describing High Temperature Hydrogen Attack (HTHA) damage for quite some time. Although there are a variety of approaches, all of them make use of describing HTHA as a time and temperature dependent phenomena that is sensitive to methane pressure. HTHA research shows the damage process is a phenomenon that is very similar to creep damage which has an exponential relationship to the applied stress and temperature. Based on these observations, the authors propose an HTHA damage assessment procedure that uses the familiar Larson Miller Parameter (LMP) approach and employs the well-known Linear Life Fraction Rule for evaluating operating condition variations in hydrogen partial pressure and temperature.
Thermal Analysis of a 9977 Package During a KAC Fire Accident
Authors: Tamburello David , Kesterson Matthew , Escobar Andrew 
Published: October 2021

Abstract
The 9977 is a US Department of Energy (DOE) shipping package used to store and transport plutonium bearing materials. The shipping package utilizes a single 6-inch diameter containment vessel with the radioactive material within SAVY-4000 containers, 3013 food-pack containers, or other sealed storage containers separated by spacers. The 6-inch containment vessel is surrounded by load distribution fixtures and a foam insulation overpack to protect against fire and impact events. A storage facility fire, which is longer and hotter than the regulatory transportation fire, is evaluated to ensure radioactive material containment is maintained. A sensitivity analysis of foam insulation reduction is considered with foam eliminated either along the inside wall of the drum body (Inner Foam) or eliminated from the outer walls of the inner chamber where the 6-inch containment vessel is located (Outer Foam). These options were considered to conservatively simulate the potential foam reduction possibilities due to aging during storage. Note that the foam insulation thermal properties were limited to their beginning of life or “as built” property values. A minimum foam thickness needed to maintain containment during the hypothetical facility fire is determined for both the Inner and Outer Foam configurations as well as for both the SAVY-4000 and 3013 food-pack container configurations.
Torsional Fatigue Test Applicable to Helical Spring Material Used in Candu Fuel Channel Spacers
Authors: Gagnon Andre , Kashyap Tejasvi , Metzger Don 
Published: October 2021

Abstract
In a particular nuclear application, separation between structural components is maintained by a helical spring such that the separating load bears across the diameter of the spring coils. Relative motion between the structural components due to changing load and temperature is accommodated by rolling of the spring. This rolling motion while under radial load results in cyclic loading of the spring material. Fatigue analysis of the cyclic loading must take into consideration the material degradation due to the unique operating environment, so testing of ex-service material is required. Standard fatigue test specimens are not possible due to the small dimensions of the spring component. Cyclic stress may be applied to the material via a reciprocating rolling motion as per the operating conditions but this approach has practical limitations with respect to cycle frequency and uncertainty in stress response. A fatigue test system has been developed in which cyclic stress is achieved by applying torsional load with respect to the axis of the helical spring. This load translates into a pure bending state of stress in the cross-section of the coils. The relationship between applied load and stress is achieved analytically through curved beam analysis. Some practical considerations in the test setup are discussed along with supporting analysis, and results obtained with specimens taken from pre-service components are presented. The outcome of the tests is compared to applicable data and it is concluded that the test method is effective in producing valid fatigue data.
Machine Learning Modeling of Dynamic Strength of Resistance Spot Welds in High Strength Steels
Authors: Zhu Jesse B. , Zhu Xian-Kui , Zhang Wei 
Published: October 2021

Abstract
Electric resistance spot welding technology has been extensively applied to join sheet metal parts in the automobile industry to decrease vehicle weight and increase its integrity. Due to the dynamic nature of motor vehicles, it is necessary to measure the dynamic strength of spot welds. Both the traditional regression approach and the state-of-the-art machine learning method are utilized in this paper to quantify the dynamic strength of spot welds based on a large database for different steels, where the dynamic strength is nominally defined as a peak load normalized by specimen thickness and weld nugget size at a specific loading rate.
Experimental results showed that the dynamic strength of spot welds is a function of the loading rate, specimen thickness, spot weld nugget size, specimen type and steel grade. To formulate the dynamic strength, the traditional regression needs to simplify the strength as a function of loading rate only, and then determine it using the best curve-fitting approach. In contrast, the machine learning method, based on an artificial neural network with built-in learning functions and algorithms, can determine a multi-variable function of dynamic strength to describe the effect of the loading rate, specimen thickness, and spot weld nugget size. To demonstrate the capability of the machine learning technology, a simple and a more complex neural network architecture are adopted to predict the dynamic strength of spot welds. The final machine learning results, advantages and disadvantages are evaluated in comparison with the regression approach.
Experimental Investigation of Jet Cross-Flow Induced Vibration of a Rod Bundle
Authors: Gad-el-Hak Ibrahim , Mureithi Njuki , Karazis Kostas , Williams Gary 
Published: October 2021

Abstract
Flow-induced vibration (FIV) is a constant concern in nuclear power plants. Demand for better thermal performance challenges the mechanical and flow characteristics of fuel designs. In the hypothetical case of a loss of coolant (LOCA) event in a reactor, the hydrodynamic pressure would increase significantly across the baffle plates. PWRs include safety features such as Loss-of-Coolant-Accident (LOCA) holes and slots in the core periphery baffles surrounding the fuel assemblies to release the pressure build up during a LOCA event. Accordingly, these fuel assemblies are subjected to combined axial and jet cross-flow at certain axial locations along their spans due to their proximity to the LOCA holes.
The jet flow could induce vibrations for fuel assemblies located near LOCA holes, which might lead to grid-to-rod fretting and thus potential fuel failure. Research on circular jet induced vibrations of rod bundles is limited. Thus, it is required to investigate the dynamical behavior of rod bundle subjected to jet flow to define the critical velocity at which the fuel rods may undergo instability.
This article presents an experimental study of jet flow induced vibrations for a 6 × 6 closely packed normal square rod bundle with a pitch-to-diameter ratio of 1.32 simulating the actual PWR fuel rod dimensions. A specialized test apparatus was designed to investigate the stability effect of jet centerline offset from array centerline (jet eccentricity). From the test results the instability threshold of the rod bundle subjected to jet cross-flow is determined. The results show that the rod array vibration is affected by the jet eccentricity. Two excitation mechanisms are identified. The first is an apparent lock-in type mechanism that maybe related to shear layer or jet oscillation. The second, more important excitation, is an apparent fluidelastic instability induced by the jet flow.
A Smart Wing Based on Vacuum-Packed Particles
Authors: Brigido-González J. D. , Burrow S. G. , Woods B. K. S. , Bartkowski P. 
Published: October 2021

Abstract
The FishBAC is a morphing aerostructure that is currently both stiffer than desired in terms of actuation energy and softer than desired for aeroelastic effects. The research aims to remove those compromises by introducing a novel material that can actively change its stiffness. The novel approach is to fill aircraft wings with particles, which can be squeezed together under vacuum pressure to make a stiff aircraft wing. When the vacuum is turned off, the grains unlock, and the wing becomes soft enough to be deformed into a new shape. This allows the wing to immediately adapt its shape to changing operating conditions — reducing noise, drag and, therefore, fuel burned.
The following research includes a new detailed mechanical modelling for morphing structures that are able to switch stiffness using vacuum-packed particles. The model is based on Euler-Bernoulli and Mohr-Coulomb analysis to capture the stiffness response of the particles at different vacuum levels. This model is computationally fast and is able to predict the variation of the stiffness accurately. The experimental and the model results agree with a relative error of less than 5%.
Excitation of Ultrasonic Natural Vibrations by Multi-Excitation Using Decentralized Control for Failure Monitoring
Authors: Tanaka Takashi , Tamura Takato , Oura Yasunori 
Published: October 2021

Abstract
The failure, e.g. fatigue crack, weld crack, and bolt loosening, of infra-structure is one of the causes of serious accidents. To prevent these accidents, structural health monitoring systems have been proposed. Among them, the evaluation methods by measurement of natural vibrations are useful for various structures because of ease in introducing a monitoring system. Currently, the natural vibrations at low-frequency range are usually used because of the difficulty of exciting natural vibrations at high-frequency range. In this paper, the excitation method of natural vibrations by multi excitation using decentralized control is developed. Firstly, the difficulty of excitation of ultrasonic natural vibrations is confirmed. Secondly, the basic performance of the multi-excitation using decentralized control is investigated by the experiment using a simple beam structure. The excitation of an ultrasonic natural vibration in the case of multi-excitation using decentralized control with the self-excitation automatically is examined. From the phase differences between each measurement signal, it is clarified that mutual synchronization is realized. Thus, it is confirmed by the measurement of vibration mode shape that an ultrasonic natural vibration is excited. Finally, it is tried to excite another natural vibration by forced entrainment.
Flexoelectric Polarization of Piezoelectric PVDF-Films Above the Curie Temperature
Authors: Seyfert Lars , ben Ammar Hassen , Schwesinger Norbert 
Published: October 2021

Abstract
A new field of research is the flexoelectric effect of solids. This quit new electromechanical energy conversion mechanism has not yet been sufficiently investigated till now.
Flexoelectricity defines the change of electrical polarization induced by changing of strain gradients in dielectric materials. In contradiction to the piezoelectric effect, all dielectric materials show a flexoelectric behavior. Flexoelectric conversion is not limited to defined temperature ranges. The effect is still present above the Curie temperature of piezoelectric materials. This interesting behavior could lead to new applications in different branches. This paper describes investigations on flexoelectricity at temperatures above the Curie temperature in piezoelectric polyvinylidene difluoride (PVDF) polymer films.
Changes of the mechanical strain gradient in the polymer film lead to a change of polarization. Furthermore, this leads to a charge separation on aluminum electrodes deposited on both sides of the polymer film. Finally, the charge transport to the electrodes in an external circuit can be measured. To analyze the flexoelectric polarization alone and in combination with other effects measurements were carried out at room temperature and above the Curie temperature. At temperatures of 130°C, i.e. far above the Curie temperature an unexpected strong polarization was found. It ranges between 50% and 80 % of the polarization values at room temperature.
Realization of Uniform Bending Strain in Piezoelectric Energy Harvesters by Gamma-Shaped Structures
Authors: Jeong Sinwoo , Lee Soobum , Yoo Hong Hee 
Published: October 2021

Abstract
Cantilever is one of the most popular structures employed for vibration-based piezoelectric energy (PE) harvesters due to its simplicity in mathematical modeling and manufacturing. However, the cantilever-shaped PE harvester (CPEH) has a nonuniform bending strain which is inefficient for piezoelectric energy harvesting. In this study, a new structure, named Γ-shaped PE harvester (ΓPEH), is proposed to achieve a uniform bending strain of the PE harvester by connecting another beam at the end of the harvester beam in 90 degree. A comparison study based on analytical solutions is made to show how the ΓPEH can outperform the CPEH and tapered PE harvester (TPEH). For a more detailed and fair comparison, the numerical models for the PE harvesters are developed using the generalized classical Ritz method, and the shape optimization is conducted under the same material volume, mass, and stress constraints. The comparison results show that the ΓPEH has higher power output than the CPEH and TPEH.
Localization of Multiple Contact-Type Failures Using Structural Intensity of Low-Frequency Vibration Caused by Frequency Down-Conversion
Authors: Tanaka Takashi , Asano Junnosuke , Oura Yasunori 
Published: October 2021

Abstract
The contact-type failure, e.g. fatigue crack in early stage, delamination of composite material and adhesive failure, leads to the serious accidents. When the object with the contact-type failure vibrates due to ultrasonic vibrations of different frequencies, the interaction of the contact interfaces of failure occurs. As the result of this interaction, the low-frequency vibration, of which frequency is the difference frequency of ultrasonic vibrations, generates (Frequency down-conversion). The detection, evaluation and localization by measurement of structural intensity of low-frequency vibration caused by frequency down-conversion has been proposed. In this paper, the performance of the proposed method in the case of multiple contact-type failures is investigated. Firstly, the detection method of contact-type failure based on frequency down-conversion of elastic vibrations is introduced. Overview of frequency down-conversion and the example of detection of contact-type failure is shown. Secondly, the proposed method for single failure is explained. By the measurement result of structural intensity of the low-frequency vibration caused by frequency down-conversion, it is confirmed that the contact-type failure can localize as the excitation point of low-frequency vibration. Finally, the influence of other failures on the localization accuracy is investigated. From these results, it is clarified that the contact-type failure, of which the excitation force of low-frequency vibration is the largest, only localizes.
Reliability Study on Spring Interconnections for Piezo-Jet Printed Electronics Under Environmental Stress
Authors: Erben Andreas , Matvieieva Nataliia , Frauendorf Moritz , Bucht André , Drossel Welf-Guntram 
Published: October 2021

Abstract
In the current paper the reliability of spring interconnections for the use in automotive applications was investigated. A commercially available connector was used for contacting a piezo-jet printed silver pad on polycarbonate. The structures were tested using vibration tests at three different temperatures (−25°C, 25°C and 85°C) and measured using four-point probe measurement system and white light spectrometry. The obtained results showed the reliability of the printed structure and the contact, despite of the contact resistance change. The reasons of this change and experimental results are discussed in the paper. The investigations described in the paper provide an initial approach to the development of spring interconnections for printed electronics.
Design of Pennate Topology Fluidic Artificial Muscle Bundles Under Spatial Constraints
Authors: Duan Emily , Bryant Matthew 
Published: October 2021

Abstract
In this paper, we investigate the design of pennate topology fluidic artificial muscle bundles under spatial and operating constraints. Soft fluidic actuators are of great interest to roboticists and engineers due to their potential for inherent compliance and safe human-robot interaction. McKibben fluidic artificial muscles (FAMs) are soft fluidic actuators that are especially attractive due to their high force-to-weight ratio, inherent flexibility, relatively inexpensive construction, and muscle-like force-contraction behavior. Observations of natural muscles of equivalent cross-sectional area have indicated that muscles with a pennate fiber configuration can achieve higher output forces as compared to the parallel configuration due to larger physiological cross-sectional area (PCSA). However, this is not universally true because the contraction and rotation behavior of individual actuator units (fibers) are both key factors contributing to situations where bipennate muscle configurations are advantageous as compared to parallel muscle configurations. This paper analytically explores a design case for pennate topology artificial muscle bundles that maximize fiber radius. The findings can provide insights on optimizing artificial muscle topologies under spatial constraints. Furthermore, the study can be extended to evaluate muscle topology implications on work capacity and efficiency for tracking a desired dynamic motion.
Design and Structural Integration of a Semi-Active Tuned Mass Damper for Improved Vibration Control on Airframe Structures
Authors: Chatziathanasiou Grigorios M. , Dimitriou Dimitris K. , Chrysochoidis Nikolaos A. , Saravanos Dimitris A. 
Published: October 2021

Abstract
Aircraft vibrations induced by low-frequency unsteady aerodynamic loads affect the comfort of passengers and reduce the airframe fatigue life. In order to attain high and broadband vibration attenuation levels, a Semi-Active Tuned Mass Damper (SATMD) is developed, that exhibits robust vibration control capabilities and requires minimal structural interference. The SATMD consists of a piezoelectric device, connected to an external Resistive-Inductive electrical circuit, and a small auxiliary mass. Simulations and testing of this damper have shown high sensitivity of its performance to: (1) the location of its structural integration and (2) its electromechanical characteristics. The current paper investigates the tailoring of these design parameters on a lab-scale airframe model, aiming at simultaneous control of 3 modes. The numerical results reveal a favorable strategy to tailor the electromechanical properties. The proposed SATMD leads to more than 10dB simultaneous reduction to all targeted modes, highlighting the robustness of the proposed damping device and the importance of the tailoring process.