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The demand for nondestructive testing has increased, especially in welding testing. In the current study, AA1060 aluminum plates were jointed using the friction stir welding (FSW) process. The fabricated joints were subjected to free vibration impact testing in order to investigate the dynamic properties of the welded joint. Damping capacity and dynamic modulus were used in the new prediction method to detect FSW defects. The data acquired were processed and analyzed using a dynamic pulse analyzer lab shop and ME'Scope's post-processing software, respectively. A finite element analysis using ANSYS software was conducted on different types of designed defects to predict the natural frequency. The results revealed that defective welded joints significantly affect the specific damping capacity. As the damping ratio increased, so did the indication of opportunities to increase the presence of defects. The finite element simulation model was consistent with experimental work. It was therefore revealed that natural frequency was insufficient to predict smaller defects.
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http://dx.doi.org/10.3390/ma11122437 | DOI Listing |
ISA Trans
July 2025
Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun, 130033, China. Electronic address:
Coordinated operation of dual-arm manipulators is essential for enhancing the load capacity and adaptability of robotic systems. However, the precise control of the internal and external forces during the coordinated operation of dual-arm manipulators can pose considerable challenges owing to factors such as force interactions, kinematic constraints, positional inaccuracies, and external disturbances. This study focused on precise force-tracking control for a dual-arm manipulator system in the presence of external disturbances and uncertainties.
View Article and Find Full Text PDFInt J Chron Obstruct Pulmon Dis
August 2025
Biomedical Instrumentation Laboratory - Institute of Biology and Faculty of Engineering, State University of Rio de Janeiro, Rio de Janeiro, Brazil.
Introduction: The contribution of respiratory models to understanding and predicting functional capacity abnormalities in chronic obstructive pulmonary disease (COPD) has not yet been investigated.
Purpose: The aims of this study were: (1) To investigate the associations between the extended Resistance-Inertance-Compliance (eRIC) and the fractional-order (FrOr) models with changes in Glittre-ADL and handgrip tests and; (2) To evaluate the accuracy of these models in predicting abnormal functional capacity in COPD.
Patients And Methods: The study was carried out in a group of 40 adults with COPD and a control group of 40 healthy individuals, both evaluated by respiratory oscillometry, spirometry, Glittre-ADL test and handgrip test.
Fundam Res
July 2025
School of Mechanical Engineering, Zhejiang Sci-Tech University, Hangzhou 310018, China.
The square exoskeleton of seahorses can transit linear motion into torsion to dissipate energy and protect the vertebrate when subjected to external disturbances. Inspired by the self-protection mechanism of the linear-to-torsion transition of the square exoskeleton of seahorses, a novel seahorse-exoskeleton-inspired structure (SES) is designed, which consists of two oblique rods and springs, and a rotational disc. The geometric relationship and dynamic model are established to reveal the corresponding nonlinear stiffness, adjustable high carrying capacity and large working range characteristics.
View Article and Find Full Text PDFResearch (Wash D C)
July 2025
College of Intelligence Science and Technology, National University of Defense Technology, Changsha 410073, China.
As an emerging frontier in biomimetic intelligent microsystems, insect-scale flapping-wing micro aerial vehicles (FWMAVs) demonstrate significant application potential due to their exceptional maneuverability and stealth capabilities. This study proposes a novel mechanical self-stabilization architecture validated through systematic engineering design to address the critical challenge of balancing dynamic instability with payload constraints in stable flight control. By integrating a piezoelectric direct-drive actuator to streamline transmission mechanisms with the optimized V-wing configuration, we developed a V-wing FWMAV prototype weighing 204 mg (wingspan: 68 mm) that demonstrates 41.
View Article and Find Full Text PDFSci Rep
July 2025
Department of Prosthodontics, Gangnam Severance Dental Hospital, Yonsei University College of Dentistry, 211 Eonju-ro, Gangnam-gu, Seoul, 06273, Republic of Korea.
This in vivo animal study aimed to evaluate the diagnostic reliability of a damping capacity assessment by correlating dental implant stability with peri-implant bone loss in a beagle dog model. Thirty-two bone-level implants were immediately placed in four beagle dogs without bone grafting. Implants were divided into platform switching and platform matching groups.
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