Accepted Manuscripts

Piotr Kohut, Krzysztof Holak, Rafal Obuchowicz, Martyna Ekiert, Andrzej Mlyniec, Lukasz Ambrozinski, Krzysztof A. Tomaszewski and Tadeusz Uhl
ASME J Nondestructive Evaluation   doi: 10.1115/1.4042397
In this study, we develop a modeling and experimental framework for multiscale identification of the biomechanical properties of the human Achilles tendon. For this purpose, we extend our coarse-grained model of collagen fibrous materials with a chemomechanical model of collagen type I decomposition. High-temperature degradation of molecular chains of collagen in a water environment was simulated using a reactive molecular dynamics method. The results from molecular dynamics simulations allowed us to define the Arrhenius equation for collagen degradation kinetics and calculate the energy of activation together with the frequency factor. Kinetic coefficients obtained from a Molecular Dynamics (MD) simulations were further used to provide better calibration of the a Coarse Grained (CG) model of collagen denaturation. For the experimental part of our framework, we performed a uniaxial tensile test of the human AT with additional use of Digital Image Correlation for ex-vivo strain tracking. Using a different path of strain tracking, we were able to include the inhomogeneity of deformation and, therefore, regional variations in tissue stiffness. Our results, both in modeling and the experimental part of the study, are in line with already existing reports and thus provide an improved approach for multiscale biomechanical and chemomechanical studies of the human Achilles Tendon.
TOPICS: Nondestructive evaluation, Mechanical properties, Modeling, Tendons, Biomechanics, Molecular dynamics, Deformation, Simulation, Biological tissues, Chain, Engineering simulation, Calibration, Molecular dynamics methods, Stiffness, Water, High temperature, Molecular dynamics simulation
Alex Paul, Peter Collins and Michael Temple
ASME J Nondestructive Evaluation   doi: 10.1115/1.4042261
A wireless non-destructive fault detection test for loose or damaged connectors is demonstrated. An architecture known as the Conditioned Multiclassification of Stimulated Emissions is pre-trained on simulated and empirical radar outputs, and transfer learning is applied to classify connected and disconnected coaxial interconnections. The two main data conditioning methods of this architecture, a statistical signal analysis tool and a convolutional filter bank, are evaluated in order to determine the cost-value proposition of each component. Novel contributions of this technique include the use of two simulation-aided convolutional filter banks to generate a multi-network ensemble and transfer learning from artificial neural networks trained on two primitive datasets revolving around the electromagnetic phenomena of reflection and filtering. A total of 560 different neural network topologies across four different signal conditioning configurations are considered, with all results compared against the current standard for measurement of cable and connection faults, time-domain reflectometry. Metrics used for comparison are time (training and evaluation), detection (connector engagement at state change detection), and clustering (projection space performance, used as a measure of transfer learning potential). It is determined that the full Conditioned Multiclassification of Stimulated Emissions architecture performs best, with nearly any neural network topology of this configuration displaying an early detection improvement of 113% and requiring 30% less time to execute an individual classification versus the current standard, all while meeting the most stringent definitions of nondestructive evaluation.
TOPICS: Nondestructive evaluation, Stimulated emission, Artificial neural networks, Filters, Signals, Topology, Electromagnetic phenomena, Flaw detection, Radar, Filtration, Reflection, Cables, Simulation
Megan/ E. McGovern, Teresa Rinker and Ryan / C. Sekol
ASME J Nondestructive Evaluation   doi: 10.1115/1.4042260
Ultrasonic metal welding is used in the automotive industry for a wide variety of joining applications including batteries and automotive wire harnessing. During electric vehicle battery pack assembly, the battery cell tab and busbar are ultrasonically welded. Quality inspection of these welds is important to ensure durable packs. A method for inspection of ultrasonic welds is proposed using pulsed infrared thermography in conjunction with electrical resistance measurements to assess the structural and electrical weld integrity. The heat source distribution was calculated to obtain thermal images with high temporal and spatial resolution. All defective welds were readily identifiable using three post-process analyses: pixel counting, gradient image, and knurl pattern assessment. A positive relationship between pixel count and mechanical strength was observed. The results demonstrate the potential of pulsed thermography for inline inspection to assess weld integrity.
TOPICS: Thermography, Ultrasonic welding, Nondestructive evaluation, Inspection, Welded joints, Automotive industry, Batteries, Electric vehicle batteries, Resolution (Optics), Welding, Manufacturing, Electrical resistance, Wire, Strength (Materials), Heat, Metals, Joining
Zhiyuan Ma, L. Lin, Shijie Jin and M.K. Lei
ASME J Nondestructive Evaluation   doi: 10.1115/1.4042177
Aim at characterizing interfacial roughness of thin coatings with unknown sound velocity and thickness, we derive a full time-domain ultrasonic reflection coefficient phase spectrum (URCPS) as a function of interfacial roughness based on the phase screen approximation theory. The constructed URCPS is used to determine the velocity, thickness, and interfacial roughness of specimens through the cross-correlation algorithm. The effect of detection frequency on the roughness measurement is investigated through the finite element method. A series of simulations were implemented on Ni-coating specimens with a thickness of 400 µm and interfacial roughness of 1.9~39.8 µm. Simulation results indicated that the measurement errors of interfacial roughness were less than 10% when the roughness satisfies the relationship of Rq=1.6%?~10.0%?. The measured velocity and thicknesses were in good agreement with those imported in simulation models with less than 9.3% error. Ultrasonic experiments were carried out on two Ni-coating specimens through a flat transducer with an optimized frequency of 15 MHz. Compared with the velocities measured by time-of-flight method, the relative errors of inversed velocities were all less than 10%. The inversed thicknesses were in good agreement with those observed by optical microscopy with less than 10.9% and 7.6% error. The averaged interfacial roughness determined by the ultrasonic inversion method were 16.9 µm and 30.7 µm, respectively. The relative errors were 5.1% and 2.0% between ultrasonic and confocal laser scanning microscope method, respectively.
TOPICS: Coatings, Nondestructive evaluation, Interface roughness, Inverse problems, Errors, Surface roughness, Lasers, Speed of sound, Simulation, Reflectance, Finite element methods, Algorithms, Engineering simulation, Transducers, Approximation, Optical microscopy, Simulation models, Simulation results, Flight, Microscopes

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