Mechanical Coupling Effects Research Articles

Prediction of Shearing and Ploughing Constants in Milling of Inconel 718

The present study proposes an integrated prediction model for both shearing and ploughing constants for the peripheral milling of Inconel 718 by using a preidentified mean normal friction coefficient. An equation is presented for the identification of normal mean friction angle of oblique cutting in milling. A simplified oblique cutting model is adopted for obtaining the shear strain and shearing constants for a tool of given helix angle, radial rake angle, and honed edge radius. The shearing and ploughing constants predicted from analytical model using the Merchant’s shear angle formula and the shear flow stress from the selected Johnson–Cook material law are shown to be consistent with the experimental results. The experimentally identified normal friction angles and shearing and edge ploughing constants for the Inconel 718 milling process are demonstrated to have approximately constant values irrespective of the average chip thickness. Moreover, the predicted forces obtained in milling aged Inconel 718 alloy are in good agreement with the experimental force measurements reported in the literature. Without considering the thermal–mechanical coupling effect in the material law, the presented model is demonstrated to work well for milling of both annealed and aged Inconel 718.

Analysis of TSV-Induced Mechanical Stress and Electrical Noise Coupling in Sub 5-nm Node Nanosheet FETs for Heterogeneous 3D-ICs

Through-silicon via (TSV)-induced mechanical stress and electrical noise coupling effects on sub 5-nm node nanosheet field-effect transistors (NSFETs) were investigated comprehensively compared to fin-shaped FETs (FinFETs) using TCAD for heterogeneous 3D-ICs. TSV-induced channel length directional stress ( $S_{ZZ}$ ) predominantly causes variations of on-state current ( $\Delta I_{on}$ ). NSFETs exhibit the greater $\Delta I_{on}$ than FinFETs because electron velocities and densities in channels vary with respect to $S_{ZZ}$ in the same directions for NSFETs but do the opposite for FinFETs. Nevertheless, TSV-induced mechanical stress is negligible when TSV is farther than keep-out zone. Meanwhile, TSV signals can be coupled to operating devices through substrate and induce capacitive and back-bias noise coupling currents ( $I_{cap}$ , $I_{b-b}$ ). NSFETs exhibit the greater $\vert I_{cap}\vert /I_{on}$ than FinFETs because its wider source/drain (S/D) epitaxies form larger depletion capacitances between drain and punch-through stopper (PTS). On the other hand, the $\vert I_{b-b}\vert /I_{on}$ is smaller for NSFETs because its parasitic bottom transistor alleviates back-bias-induced potential barrier lowering. Furthermore, wide diameter of Cu of TSV increases $\vert I_{b-b}\vert /I_{on}$ only, but short rise time of TSV signals increases both $\vert I_{cap}\vert /I_{on}$ and $\vert I_{b-b}\vert /I_{on}$ . Unfortunately, conventional devices cannot satisfy criterion for analog applications ( $\vert I_{cap}$ , $I_{b-b}\vert /I_{on} %); therefore, a new strategy inserting bottom oxide (BOX) beneath the S/D with undoped PTS is suggested. The $\vert I_{cap}\vert /I_{on}$ for NSFETs decreases by undoped PTS, but not for FinFETs due to a remnant depletion capacitance between fin and PTS. The $\vert I_{b-b}\vert /I_{on}$ for NSFETs decreases remarkably due to completely blocked $I_{b-b}$ path, but FinFETs still have $I_{b-b}$ path under the fin. Therefore, NSFETs with BOX and undoped PTS are the most suitable for sub 5-nm node heterogeneous 3D-IC, especially in analog applications.

Magnetoelastic coupling effect of Fe10Co90 films grown on different flexible substrates**Project supported by the National Natural Science Foundation of China (Grant Nos. 11674336 and 11874150).

The magneto–mechanical coupling effect and magnetic anisotropy of Fe10Co90 (FeCo) films deposited on silicon wafer (Si), flexible polyethylene terephthalate (PET), freestanding polydimethylsiloxane (PDMS), and pre-stretched 20% PDMS substrates were studied in detail. The loop squareness ratio Mr/Ms and the coercive Hc of the FeCo film grown on a PET substrate can be obviously tuned by applying a small tensile-bending strain, and those of the FeCo film grown on a freestanding PDMS substrate can only be slightly changed when applying a relatively large tensile bending strain. For the FeCo film prepared on a 20% pre-stretched PDMS, a wrinkled morphology is obtained after removing the pre-strain. The wrinkled FeCo film can keep the magnetic properties unchanged when applying a relatively large tensile bending strain perpendicular to the wrinkles. This reveals that PDMS is an ideal substrate for magnetic films to realize flexible immutability. Our results may help for developing flexible magnetic devices.

A printable P(VDF-TrFE)-PZT Composite with Very High Piezoelectric Coefficient

In this paper a significant advance in the piezoelectric properties of poly(vinylidenefluoride-trifluoroethylene)-lead zirconate titanate (P(VDF-TrFE)-PZT) composite ink has been achieved by coating the ceramic particles prior to formulation with a polymeric surfactant containing carboxylic acid anhydride functional groups and the piezoelectric response of a unimorph cantilever is further enhanced by introducing a reinforced substrate. The measured effective transverse piezoelectric coefficient (d31eff) was -56 pm/V, which is 3.3 times higher than that of the same composite without surfactant and is the highest reported for a printable polymer-ceramic composite. In addition, the printability of the ink and dispersion of the ceramic particles was enhanced. The samples were fabricated by stencil printing of a single piezoelectric layer on a flexible PET substrate followed by curing at only 120°C, thus enabling utilization on a wide range of substrates. The results also show the improved particle dispersion and layer quality in 0-3 composite inks with surfactant added and the effect of sample structure and mechanical coupling between the hard ceramic particles and the soft matrix. The developed composite ink is suitable, for example, in sensors in printed wearable and portable electronics.

Study on the damage statistical strength criterion of backfill with crack under thermo-mechanical coupling

ABSTRACT Aiming at backfill with crack under the thermo-mechanical (TM) coupling, the concepts of crack macro-damage, loading meso-damage, thermal meso-damage, and total damage of backfill were proposed. Based on the statistical damage theory, considering the coupling effects of temperature, load and initial crack, a damage evolution model of backfill with crack under TM coupling effects was established. Based on this, the strength criterion of backfill with crack considering the effects of thermal and mechanical coupling was constructed by multivariate function full differential method. The research shows that: (1) The theoretical curves of damage evolution model and strength criterion of backfill with crack under TM coupling are in good agreement with the test curves, which verifies the rationality of the model. (2) The initial thermal damage decreases first and then increases with increasing temperature, reaches a minimum value at 40°C, and generally shows a “V” -shaped distribution law. The coupling effect of temperature and crack aggravates the total damage of the backfill. (3) The strength criterion can reflect the relationship between the stress and strain of each limit state and the parameters of backfill with crack under different temperature conditions and can provide a certain reference for the evaluation of the stability of backfill with geological defects such as joints and crack in deep high temperature mines.

Study on Viscous Fluid Flow in Disordered-Deformable Porous Media Using Hydro-mechanically Coupled Pore-Network Modeling

We investigate viscous fluid flows and concurrent fluid-driven deformations in porous media. The hydro-mechanically (H-M) coupled pore-network model (PNM) is developed, which combines the two-dimensional square-lattice PNM and block-spring model. The single-/two-phase flows into saturated deformable porous media are simulated through iterative two-way coupling method in H-M coupled PNM. A comparison between simulations and laboratory observations on flow patterns, solid deformation behaviors, and pressure responses ensures the validity of our H-M coupled PNM in both single-/two-phase flows. Parametric studies using the validated model examine the effects of mechanical coupling, stiffness of solid particles, the viscosity of invading fluids, injection flow rate, and degree of disorder during immiscible viscous fluid injection. The viscous fluid-driven deformation increases the pore throat size and hence reduces the injection pressure. In particular, the viscosity of invading fluid significantly alters the patterns of fluid propagation and solid deformation, along with a transition from the viscous fingering to the stable displacement with increasing viscosity. Moreover, the structural disorder in porous networks magnifies the irregular flow pattern, the pressure fluctuation associated with Haines jumps, and the poromechanical deformation. The particle-level force analysis delineates two distinct regimes: fluid invasion with no deformation and drag-driven deformation, which depends on the balance between the seepage drag force and the skeletal force. The presented results contribute to a better understanding of the H-M coupled fluid flows during the injection of viscous fluids into disordered-deformable porous media.

Bionic optimization design for a CNC turntable based on thermal–mechanical coupling effect

During the machining process, the thermal–mechanical coupling effect of CNC turntable is produced by the action of variable loads and various heat sources. In order to improve the static and dynamic characteristics under thermal–mechanical coupling effect, a novel bionic optimization design method for CNC turntable was proposed. The finite element modal analysis on a CNC turntable was carried out to obtain the weak link of its dynamic characteristics, and the thermal–mechanical coupling analysis on the CNC turntable was conduct to reveal the influence of the thermal–mechanical coupling effect on the dynamic characteristics of the CNC turntable. In view of the good mechanical properties of Victoria amazonica, bionic design for the CNC turntable was carried out based on the strong similarity of structure and function. The optimization objectives and design variables of bionic CNC turntable were selected according to the thermal–mechanical coupling and modal analysis results, and the influence law of the design variables on the optimization objectives was studied by sensitivity analysis method. The optimal solution to bionic CNC turntable was obtained through response surface optimization, which made the maximum deformation was reduced by 2.37%, the mass was reduced by 15.60%, and the first six order natural frequencies were increased. The feasibility of the proposed bionic optimization design method for CNC turntable was verified through comparing the first six order natural frequencies of modal experimental results with optimization results. Therefore, the bionic optimization method provides a new idea for structural design of CNC machine tools’ parts to improve the static and dynamic characteristics.

Modified equivalent single layer theory for dynamic analysis of rotating composite shafts

This paper presents a dynamic study of the rotating composite shaft vibratory behavior and the effects of different mechanical coupling. In fact, Modified ESLT is generalized from ESLT to consider not only the effects of fiber orientation, stacking sequences and shear-normal coupling but also the influences of different mechanical coupling on rotating composite shafts. The close agreement in the achieved results proves the efficiency of the developed finite element based on Modified ESLT. Furthermore, obtained results revealed that different mechanical coupling, fiber orientations and stacking sequences have an important influence on the rotating composite shaft dynamic behavior.

Dynamics of beating cardiac tissue under slow periodic drives.

Effects of mechanical coupling on cardiac dynamics are studied by monitoring the beating dynamics of a cardiac tissue which is being pulled periodically at a pace slower than its intrinsic beating rate. The tissue is taken from the heart of a bullfrog that includes pacemaker cells. The cardiac tissue beats spontaneously with an almost constant interbeat interval (IBI) when there is no external forcing. On the other hand, the IBI is observed to vary significantly under an external periodic drive. Interestingly, when the period of the external drive is about two times the intrinsic IBI of the tissue without pulling, the IBI as a function of time exhibits a wave packet structure. Our experimental results can be understood theoretically by a phase-coupled model under external driving. In particular, the theoretical prediction of the wave-packet period as a function of the normalized driving period agrees excellently with the observations. Furthermore, the cardiac mechanical coupling constant can be extracted from the experimental data from our model and is found to be insensitive to the external driving period. Implications of our results on cardiac physiology are also discussed.

Hydrodynamic analysis of a novel modular floating structure system with central tension-leg platforms

ABSTRACT The present work proposed a novel modular structural system with central tension-leg platforms and outermost wave energy converters (marked as MTLPW). The hydrodynamic interaction effect and the mechanical coupling effect between the WECs and the TLP have been taken into consideration, and the effects of key design parameters of the WEC on the hydrodynamic characteristics of the MTLPW system have been clarified. The results indicate that the outermost WEC can significantly reduce the surge response of the central TLP and produce considerable wave energy. In addition, the effects of different connection types, pretension levels and additional heave plates on the hydrodynamic performance of the MTLPW system have been further investigated, and the results indicate that both the outermost WEC module and the additional heave plate can be promising and available for improving the hydrodynamic performance of the initial MTLPW system.

An Efficient Cell-Based Smoothed Finite Element Method for Free Vibrations of Magneto-Electro-Elastic Beams

Magneto-electro-elastic (MEE) materials are widely used in intelligent structure systems owing to their electronic, mechanical and magnetic coupling effects. To overcome the over-stiffness of the finite element method (FEM) stiffness matrix and simulate the free vibration of MEE structures more accurately, we introduced the gradient smoothing technique into MEE multi-physical-field FE model and thereby deduced the cell-based smoothed finite element method (CS-FEM) equations of MEE materials. The MEE beams and layered beam affected by the coupling effect of multiple physical fields under different boundary conditions were computed by CS-FEM, after comparing results with those of FEM and reference solutions, the accuracy and efficiency of CS-FEM were validated.

Tunable triple‐shape memory composite fabricated by selective crosslinking of polycaprolactone/poly(butylene adipate‐co‐terephthalate)/bentonite

ABSTRACTIn this work, we fabricated a triple‐shape memory polymeric composite (TSMPc) by electron beam irradiation of ε‐polycaprolactone (ε‐PCL)/poly(butylene adipate‐co‐terephthalate) (PBAT)/bentonite(50/50/4) (wt %). The 95 ± 5 kGy was confirmed to be the saturated irradiation dose by both high‐temperature storage modulus and the equilibrated relaxation modulus at nonlinear elastic region. Further results demonstrated that sample exposed to 41.4 kGy exhibited excellent triple‐shape memory effect (TSME) though there existed slight plastic flow in PBAT. The two fixity ratios and total recovery ratio can be as high as 99.9, 98.3, and 94.7%. Besides, the strength of irradiated PBAT was improved because of the synergistic mechanical coupling effect from PCL and bentonite. In the meantime, this synergistic effect also improved the integral TSME and the stability of all shapes. Eventually, we made a comparison among the controllable factors, the crosslinking density and amount of deformation ΔεB → C were believed to have more influences on the stability of temporary shapes and the recovery behavior during the shape memory cycle “A → B → C → Br → Ar.” © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48577.

Effects of device structure on thermo-optic switch and design optimization

The study on reliability of multi-layer structure of thermo-optic switch under thermal mechanical coupling effect is the basic research subject in modern micro-optoelectronics. Power consumption and response time are the most important performance indexes. Based on the generalized thermoelasticity theory, thermo-optic switch models of various structures are built to simulate the temperature and stress field for structure optimization. The numerical results show that an appropriate cross-section shape can reduce the switch power consumption without prejudice to the response speed, the refractive index of the core layer varies with the temperature, and the inter-layer thermal mismatching stress of the double-ridge structure is the maximum. The above findings will introduce new ideas for research and development and design of new optic switches.

Nonlinear normal modes and primary resonance for permanent magnet synchronous motors with a nonlinear restoring force and an unbalanced magnetic pull

The unbalanced magnetic pull (UMP) in permanent magnet synchronous motors (PMSMs) leads to the generation of vibrations and noise because of mechanical and magnetic coupling effects. This paper investigates the nonlinear oscillations of a PMSM based on a Jeffcott rotor-bearing system, and the effects of the UMP, nonlinear restoring forces due to the Hertz contact force and bearing clearance, rotor weight and rotor mass eccentricity are considered. A second-order approximate solution in the primary resonance case is obtained by applying the multiple-scale perturbation method. The Routh–Hurwitz criterion is utilized to investigate the stability of the obtained solution. The linear natural frequencies of the horizontal and vertical modes show little difference based on the constructed model. The localized oscillations and nonlocalized oscillations of the rotor-bearing system are analyzed through its frequency response curves by introducing different values of system parameters. The response curves exhibit hard spring characteristics with unstable regions and jump phenomena. Detailed numerical research including Poincare map and bifurcation diagram reveals the effect of excitation amplitude on the system. Additionally, this work provides some theoretical and practical guidance for the design of PMSMs with strong dynamic behaviors.

On the Cross Coupling Effects in Structural Response of Switched Reluctance Motor Drives

Vibration and acoustic noise in switched reluctance motor (SRM) drives have been investigated and addressed frequently. However, the focus of most the paper is on vibration of the stator frame due to radial electromagnetic forces acting on the stator teeth. In this paper, a comprehensive vibration analysis for a SRM assembly using finite element (FE) method is conducted, which considers the stator and rotor vibrations due to radial electromagnetic force as well as the effect of mechanical coupling on the vibration between the stator and rotor. First, an experimental modal test was performed to extract modal parameters and to observe the coupling effect. The parameters were then used to adjust and validate the FE model that was used to obtain transfer functions for vibration characterization. Using the frequency domain representation of the radial magnetic force vector and the calculated transfer functions, radial and tangential vibration components have been predicted.

Thermal–Mechanical Coupling Analysis and Experimental Study on CNC Machine Tool Feed Mechanism

As the CNC machine tool feed mechanism is affected by joint action of heat and load during the working process, thermal–mechanical coupling analysis and experimental research on CNC machine tool feed mechanism are conducted. On the basis of exploring the thermal–mechanical coupling effect of CNC machine tool feed mechanism, a thermal–mechanical coupling dynamic analysis method is proposed through combining multi-step finite element simulation with temperature field experiment. According to the proposed method, the transient and steady-state simulation analysis on CNC machine tool feed mechanism are conducted and conclusions obtained are as follows, before the whole feed mechanism reaches thermal balance state, the thermal–mechanical coupling effect makes the deformation of the feed mechanism increase with the temperature rising. The correctness of the proposed thermal–mechanical coupling dynamic analysis method was verified by the contrastive analysis of the experiments. Therefore, in the process of CNC machine tool feed mechanism’s analysis and design, the influence of thermal–mechanical coupling effect on dynamic performance should be considered.

(Invited) Multiscale Stress-Transport-Kinetics Continuum Models for Lithium-Metal Batteries-Relevance of Richard Alkire’s Electrodeposition Legacy for Next-Generation Batteries

Multiscale is a term commonly used/abused in the literature. First, we will quantify the meaning of ‘multiscale’ models. Richard Alkire’s selected contributions in the field of electrodeposition – Multiscale models (continuum + KMC) and finite element methods for shape changes will be reviewed. The relevance of the same for the current hot-topic in the field of lithium-metal batteries – modeling, simulating and controlling the dendrite formation in lithium-metal batteries will be discussed. There is significant interest in using pressure as an external control to achieve proper cyclability and desirable deposition characteristics in high energy-density lithium metal anodes. We aim to provide useful predictions of cell-level variables by using a multiscale approach in which local electrochemical effects of pressure and mechanical coupling in the anode are coupled with macro homogeneous models of porous cathodes to study the effect of pressure on voltage response. Progress made in multiscale models coupling stress, transport and kinetic models at different length scales and our perspectives will be presented. Our interest lies in efficient (ideally real-time) simulation of the coupled models. Acknowledgements The authors would like to thank for the financial support of this work by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the DOE through the Advanced Battery Material Research (BMR) Program (Battery500 consortium) and the Clean Energy Institute (CEI) at the University of Washington and the Washington Research Foundation (WRF) for their partial monetary support during this work.

Analysis of a Vibrating Motor Considering Electrical, Magnetic, and Mechanical Coupling Effect

A vibrating motor is a multi-physics product in which there is coupling between electrical, magnetic, and mechanical domains. To obtain a more accurate analysis, nonlinear parameters, such as inductance, speedance, and force factor, are considered as functions of current and displacement based on the finite element method. By solving a voltage equation using a numerical iteration method, current and displacement at each frequency of the vibrating motor can be calculated. The validity of the analysis method was demonstrated by comparing the results of the experiment with those of the simulation and they were found to be similar.

Hydrodynamic analysis of a modular multi-purpose floating structure system with different outermost connector types

The present work investigates the effect of different outermost connector types on the hydrodynamic responses of a modular multi-purpose floating structure (MMFS) system. The MMFS system is preliminarily designed for a mild sea zone, which is composed of a number of standardized floating modules. In this study, the MMFS system has been simplified as a seven-module connected system. Considering the structural deformation of the MMFS system mainly occurs in the connectors among adjacent modules, each module is viewed as a rigid body. Both the hydrodynamic interaction effect and mechanical coupling effect among modules have been taken into consideration in the time-domain analysis. Different outermost connector designs have been proposed and investigated for the MMFS system. The results indicate that the hydrodynamic responses of the MMFS system are sensitive to the effects of the connector types, the wave phase, and the wavelength. The hinge-type design of the outermost connector can significantly reduce the extreme responses of both the bending moment and the shear force of the connectors. The additional PTO damper design for the outermost hinge-type connector can effectively reduce the motion of the outermost module, and also produce considerable wave energy.

Rowing together: Interpersonal coordination dynamics with and without mechanical coupling

Although most research on interpersonal coordination focuses on perceptual forms of interaction, many interpersonal actions also involve interactions of mechanical nature. We examined the effect of mechanical coupling in a rowing task from a coupled oscillator perspective: 16 pairs of rowers rowed on ergometers that were physically connected through slides (mechanical coupling condition) or on separate ergometers (no mechanical coupling condition). They rowed in two patterns (in- and antiphase) and at two movement frequencies (20 and 30 strokes per minute). Seven out of sixteen pairs showed one or more coordinative breakdowns, which only occurred in the antiphase condition. The occurrence of these breakdowns was not affected by mechanical coupling, nor by movement frequency. For the other nine pairs, variability of steady state coordination was substantially lower in the mechanical coupling condition. Together, these results show that the increase in coupling strength through mechanical coupling stabilizes coordination, even more so for antiphase coordination.