Multi-Objective Optimization Design of a Novel Integral Squeeze Film Bearing Damper

In order to better control the vibration of the rotor system so as to improve the stability and safety of the rotor, a novel vibration control solution is needed. In this paper, the multi-objective optimization problem is used for designing a novel integral squeeze film bearing damper (ISFBD). The method attempts to reduce the stiffness and stress convergence of ISFBD, which can greatly decrease the transmitted force of the rotor system and better use the damping effect to dissipate the vibration energy. The finite element model of ISFBD is established to analyze the stiffness and stress, and the correctness of the calculation is verified by setting up a stiffness test platform. The sensitivity of different structural parameters of stiffness and stress is analyzed by ANOVA. Meanwhile, the non-dominated sorting genetic algorithm (NSGA-II) and grey correlation analysis (GRA) algorithms are coupled for multi-objective optimization of stiffness and stress. The results indicate that optimized ISFBD can distribute 26.6% of the rotor system’s energy and reduce 59.3% of the transmitted force at the bearing location. It is also proved that the optimization strategy is effective, which can provide a useful method for ISFBD design in practical applications.

Modified IWO algorithm for topological optimum synthesis of the displacement amplifying compliant mechanism

The conventional mechanisms transmitted force and displacement through rigid members (high stiffness) and traditional joints (with high softness), where recently, researchers have come up with new systems called compliant mechanisms that transfer power and mobility through the deformation of their flexible members. One of the most frequently used approaches for designing compliant mechanisms is topology optimization. Extracting the optimal design of a displacement amplifying compliant mechanism using the modified Invasive Weed Optimization (MIWO) method is the current study's main novelty. The studied mechanism is a compliant micro-mechanism that can be used as a micrometric displacement amplifier. The goal of this synthesis is to maximize the output-to-input displacement ratio. In this research, a new random step is added to the Invasive Weed Optimization (IWO) method; the new seeds can be spread farther from their parents, which can be improved the algorithm's abilities. The results show that the use of the modified IWO algorithm for this problem has led to a significant improvement over the results from similar articles.

Multibody-Based Piano Action: Validation of a Haptic Key

A piano key prototype actuated by a custom-made linear actuator is proposed to enhance the touch of digital pianos by reproducing the force feedback of an acoustic piano action. This paper presents the design and the validation of the haptic device. The approach exploits a multibody model to compute the action dynamics and the corresponding force on the key in real time. More specifically, a grand piano model that includes the five action bodies, its geometry and the specific force laws, is computed in the haptic device. A presizing step along with Finite Element Method (FEM) analysis produced an especially made actuator satisfying the design requirements, in particular the highly dynamic nature of the force to be transmitted. Force peaks, up to 50 (N) in less than 20 (ms), are reachable with low power consumption. Compared to previous solutions: (i) the key physical characteristics are preserved; (ii) the feedback is based on a real-time multibody model that is easily configurable and interchangeable; (iii) an experimental validation of the actuator within the prototype is developed and demonstrates its feasibility. The results confirm that the voice coil can produce suitable haptic feedback. In particular, rendering a grand piano action within the device shows promising haptic force profiles.

The Dynamic Response of the Vibrating Compactor Roller, Depending on the Viscoelastic Properties of the Soil

The present paper addresses the problem of the dynamic response of a vibrating equipment for soil compaction. In essence, dynamic response vibrations are analysed by applying an inertial-type perturbing force. This is generated by rotating an eccentric mass with variable angular velocity, in order to reach the regime necessary to ensure the degree of compaction. The original character of the research is that during the compaction process, the soil layers with certain compositions of clay, sand, water and stabilizing substances change their rigidity and/or amortization. In this case, two situations were analysed, both experimentally and with numerical modelling, with special results and practical engineering conclusions, favourable to the evaluation of the interaction between vibrator roller–compacted ground. We mention that the families of amplitude–pulse and transmitted force–pulse response curves are presented, from which the dynamic effect in the compaction process results after each passage on the same layer of soil, until the necessary compaction state is reached.

Tethering Piezo channels to the actin cytoskeleton for mechanogating via the E-cadherin-β-catenin mechanotransduction complex

The mechanically activated Piezo channel plays a versatile role in conferring mechanosensitivity to various cell types. However, how it incorporates its intrinsic mechanosensitivity and cellular components to effectively sense long-range mechanical perturbation across a cell remains elusive. Here we show that Piezo1 is biochemically and functionally tethered to the actin cytoskeleton via the E-cadherin-β-catenin mechanotransduction complex, whose perturbation significantly impairs Piezo1-mediated responses. Mechanistically, the adhesive extracellular domain of E-cadherin interacts with the cap domain of Piezo1 that controls the transmembrane gate, while its cytosolic tail might interact with the cytosolic domains of Piezo1 that are in close proximity to its intracellular gates, allowing a direct focus of adhesion-cytoskeleton-transmitted force for gating. Specific disruption of the intermolecular interactions prevents cytoskeleton-dependent gating of Piezo1. Thus, we propose a force-from-filament model to complement the previously suggested force-from-lipids model for mechanogating of Piezo channels, enabling them to serve as versatile and tunable mechanotransducers.HighlightsRevealed biochemical and functional interactions between Piezo1 and the E-cadherin-β-catenin-F-actin mechanotransduction complex.Identified critical mechanogating domains of Piezo1 as E-cadherin binding domains.Specific disruption of the intermolecular interactions between Piezo1 and E-cadherin prevents cytoskeleton-dependent gating of Piezo1.Proposed a tether model for mechanogating of Piezo channels.

Femur Bone Stress Analysis in CFD Modules with Parallel Processing

This research focuses on the aspect of femur bone modeling that will change structure in response to mechanical stresses that can be induced to bone formation. 3D femur bone models are constructed by configuring material and geometric conditions and respecting patients' specific features, providing realistic and performant structural analysis. Using CFD concept, a three-dimensional model of the femur system was established, calculated the level of stress, the distribution of the femur and the magnitude of the transmitted force. This study describes a 3D construction process as well as the generation of the mesh based on a parallel processing of eight processors. Our main contribution revolves around the use of CFD modules to simulate stress measurement in the bone and study their impact in the case of external force exerted with successive values 10N, 50N and 100N

Design, Fabrication, and Testing of a Novel 3-DOF Energy Harvester With Single Piezoelectric Stack

This paper presents the design, fabrication, and testing of a novel single stack-based piezoelectric energy harvester (PEH) for harvesting energy from three-degree-of-freedom (3-DOF) force excitation. One uniqueness lies in that the 3-DOF energy harvesting is implemented by using one piezoelectric stack. To scavenge energy from the 3-DOF input force, the proposed PEH is constructed with several force transmission mechanisms and slider mechanisms. The direction of the input force is first changed by the force transmission mechanisms, and the redundant force components are eliminated by the slider mechanisms. The transmitted force is then amplified by a two-stage force amplifier mechanism to improve the electric power output. The key parameters were found by establishing an analytical model of the proposed PEH. The best output performance of the PEH is achieved by selecting and optimally designing the key parameters. A prototype harvester was fabricated, and several experimental studies were conducted to verify the device performance. Results show the effectiveness of the developed 3-DOF PEH under the input force applied in x-axis, y-axis or z-axis. Furthermore, the issues that affect the practical application are discussed.