Modeling of Magnetoelectric Microresonator Using Numerical Method and Simulated Annealing Algorithm

A comprehensive understanding of the linear/nonlinear dynamic behavior of wireless microresonators is essential for micro-electromechanical systems (MEMS) design optimization. This study investigates the dynamic behaviour of a magnetoelectric (ME) microresonator, using a finite element method (FEM) and machine learning algorithm. First, the linear/nonlinear behaviour of a fabricated thin-film ME microactuator is assessed in both the time domain and frequency spectrum. Next, a data driven system identification (DDSI) procedure and simulated annealing (SA) method are implemented to reconstruct differential equations from measured datasets. The Duffing equation is employed to replicate the dynamic behavior of the ME microactuator. The Duffing coefficients such as mass, stiffness, damping, force amplitude, and excitation frequency are considered as input parameters. Meanwhile, the microactuator displacement is taken as the output parameter, which is measured experimentally via a laser Doppler vibrometer (LDV) device. To determine the optimal range and step size for input parameters, the sensitivity analysis is conducted using Latin hypercube sampling (LHS). The peak index matching (PIM) and correlation coefficient (CC) are considered assessment criteria for the objective function. The vibration measurements reveal that as excitation levels increase, hysteresis variations become more noticeable, which may result in a higher prediction error in the Duffing array model. The verification test indicates that the first bending mode reconstructs reasonably with a prediction accuracy of about 92 percent. This proof-of-concept study demonstrates that the simulated annealing approach is a promising tool for modeling the dynamic behavior of MEMS systems, making it a strong candidate for real-world applications

WAAM-Fabricated Laminated Metal Composites

Laminated metal composites are a promising design since the hybrid design enables superior and tailorable material properties compared with bulk material. The article introduces for the first time, laminated metal composites consisting of multiple bilayers of alternating layers of ductile and high-strength steel processed by wire arc additive manufacturing (WAAM). The layup of the laminated metal composites is built up by alternating deposits made of ductile steel and high-strength steel type wires. Governing parameters in the fabrication process affecting the material properties, such as dilution, are discussed. Enhanced material properties of the laminated metal composites fabricated by WAAM are investigated under static tensile, impact and tension-tension high-cycle-fatigue loading and compared to the relating homogenous weld metal. Potential reasons for the retardation of crack propagation in laminated metal composites fabricated by WAAM compared to findings in roll-bonded laminated metal composites are discussed. WAAM is conducted by a collaborative robot providing a high level of flexibility in respect to geometry and scalability. Tailorability of material properties through WAAM-fabricated laminated metal composites adds an important layer of flexibility which has not been explored yet

Material mechanisms of Cu/Ni nanolaminate coatings resulting in lifetime extensions of welded joints

Metal nanolaminate coatings are introduced as a new approach in post-weld treatment methods. A Cu/Ni nanolaminate coating is electrodeposited from a single Cu/Ni citrate bath onto a butt-welded tension-tension fatigue specimen. The nanolaminate coating consists of a Ni base layer and 160 alternating Cu and Ni layers. The specimen is tested in tension-tension fatigue with a stress range close to the yield strength of the specimen. This first study reveals surprisingly high lifetime extensions of welded joints. The tested specimens are examined using FIB/SEM and TEM. Local roughness measurements are carried out with AFM. This leads to observations on crack behavior of nanostructured Cu/Ni multilayers. The Cu layers show initial multi-crack formation, while the cracks arrest at the Cu/Ni interfaces. The Ni layers bridge those cracks and each Ni layer tears individually. Hypotheses are formed on the fatigue behaviour of Cu/Ni multilayers