Meccanica最新文献

{"title":"Dynamic mechanical behavior of ice with different cotton contents","authors":"Kai Guo,&nbsp;Yusen Zhang,&nbsp;Enling Tang,&nbsp;Zhiqiang Liang,&nbsp;Mengzhou Chang,&nbsp;Yafei Han,&nbsp;Chuang Chen,&nbsp;Liping He","doi":"10.1007/s11012-024-01915-x","DOIUrl":"10.1007/s11012-024-01915-x","url":null,"abstract":"<div><p>In order to study the dynamic compressive mechanical properties of hail, artificial ice specimens were prepared by adding cotton wool into deionized-distilled water. Dynamic compression experiments of ice specimens under different strain rates were carried out by using the Split Hopkinson Pressure Bar (SHPB). Furthermore, based on finite element software LS-DYNA, numerical simulations were conducted to evaluate applicability of mechanical parameters of ice under impact load. The results show that the specimens have a secondary loading phenomenon under the action of stress wave, and this phenomenon is more obvious with the increase of cotton content; under a given content of cotton and low strain rate, the compressive strength of ice is increased with the increasing of the strain rate; under high strain rate, the compressive strength of ice with 0% and 0.3% cotton is maintained as a constant, but a discrete result is observed for ice with 0.5% cotton; when the velocity of impact bar is in the range of 1.35–11.83 m/s, the compressive strengths of the specimens with cotton content of 0%, 0.3% and 0.5% are 3.3 MPa, 4 MPa and 8.1 MPa, respectively. Beyond that, morphology analysis shows that the edge of the specimen is damaged during impact process and the flying velocity of fragments increases with external force.</p></div>","PeriodicalId":695,"journal":{"name":"Meccanica","volume":"59 11","pages":"2081 - 2095"},"PeriodicalIF":1.9,"publicationDate":"2024-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142875232","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Preface to the Special Issue of Meccanica “Sixty years of thermodynamics of continuous media (1963–2023)”","authors":"Vito Antonio Cimmelli,&nbsp;David Jou,&nbsp;Antonio Sellitto","doi":"10.1007/s11012-024-01900-4","DOIUrl":"10.1007/s11012-024-01900-4","url":null,"abstract":"","PeriodicalId":695,"journal":{"name":"Meccanica","volume":"59 10","pages":"1639 - 1641"},"PeriodicalIF":1.9,"publicationDate":"2024-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142811289","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Design and simulation of a desk-size parallel kinematic machine for simulation of seismic events","authors":"Sergio Pacioni,&nbsp;Luca Carbonari,&nbsp;Milena Martarelli,&nbsp;Massimo Callegari","doi":"10.1007/s11012-024-01911-1","DOIUrl":"10.1007/s11012-024-01911-1","url":null,"abstract":"<div><p>This paper presents the design process and the virtual testing of a lab equipment for earthquake simulations. The machine object of study is a redundantly actuated platform with parallel kinematics topology. As known, this kind of architecture owns extremely interesting features which make PKMs (Parallel Kinematics Machines) particularly feasible for recreating seismic events, in terms of displacements, accelerations and, consequently, inertial solicitations. Nonetheless, the use of a parallel over-actuated structure makes the design process challenging under many points of view: the mechanics, the sensorisation, and even the control of the shaking device must be tackled carefully from the design stage to come out with effective solutions. The paper provides details around the choices performed and shows the results of a dynamic simulations campaign to demonstrate the performance offered by the simulator in an actual use case.</p></div>","PeriodicalId":695,"journal":{"name":"Meccanica","volume":"59 12","pages":"2313 - 2323"},"PeriodicalIF":1.9,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142906021","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nonlinear control and parametric uncertainties of flexible-joint robots","authors":"Jeferson J. Lima,&nbsp;Mauricio A. Ribeiro,&nbsp;Max M. D. Santos,&nbsp;Frederic C. Janzen,&nbsp;Jose M. Balthazar,&nbsp;Angelo M. Tusset","doi":"10.1007/s11012-024-01891-2","DOIUrl":"10.1007/s11012-024-01891-2","url":null,"abstract":"<div><p>This study examines the relationship between the nonlinear behavior of the flexible joints of a fourth-degree-of-freedom robot and the controllability and parametric uncertainties of the system. The initial section of the paper presents the dynamic modeling of the robot and the proposed control strategies. This is followed by a parametric sensitivity analysis, which defines the optimal control strategy to be applied. Finally, the configuration of the experimental robot with flexible joints is presented. The SDRE and LQR strategies are related in the study, both in discrete mode and intended for use in the control unit. The final phase of the study involved the presentation of the results obtained when the robot was controlled using flexible joints. The findings demonstrated a positive outcome for the SDRE control strategy.</p></div>","PeriodicalId":695,"journal":{"name":"Meccanica","volume":"59 12","pages":"2325 - 2347"},"PeriodicalIF":1.9,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142906024","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nonlinear magneto-mechanical combined vibration characteristics of magnetic gear two-speed transmission","authors":"Junliang Du,&nbsp;Dawei Liu,&nbsp;Tingzhi Ren,&nbsp;Yixuan Tian","doi":"10.1007/s11012-024-01909-9","DOIUrl":"10.1007/s11012-024-01909-9","url":null,"abstract":"<div><p>The replacement of mechanical planetary gears with magnetic gears (MGs) is an emerging transmission solution for electric vehicles that reduce shock and vibration. This article proposes magnetic two-speed transmission and examines the influence of the noncontact torque of MGs, the meshing stiffness of mechanical gears, and the system load on the vibration of magneto-mechanical combined transmission systems. First, the noncontact torque of an MG is analysed on the basis of the magnetic field modulation principle. A set of dynamic equations was subsequently constructed on the basis of the centralized parameter method. Thereafter, with the principle of harmonic balance, a rapid method for constructing a nonlinear vibration harmonic balance solution for a magneto-mechanical combined vibration system in matrix form is obtained. Finally, simulations and prototype tests were conducted. The results show that noncontact torque consists of stable torque and ripple torque. They also interact with mechanical gears to affect system vibration. he vibration amplitude of the inner rotor is sensitive to the pulsating torque, whereas the vibration of the ferromagnetic pole-pieces is sensitive to the meshing stiffness. The stable torque and load dynamic balance affect the natural frequency of the system. The system demonstrates “load‒stiffness adaptive” characteristics compared with those of pure mechanical gearing. The proposed Harmonic Balance Method can quickly calculate this characteristic, and it offers a theoretical basis for dynamic analysis and vibration reduction in magnetic two-speed transmissions.</p></div>","PeriodicalId":695,"journal":{"name":"Meccanica","volume":"59 12","pages":"2295 - 2312"},"PeriodicalIF":1.9,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142906020","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of turbulence boundary conditions on Spalart-Allmaras RANS simulations for active flow control applications","authors":"Navid Monshi Tousi,&nbsp;Josep M. Bergadà,&nbsp;Fernando Mellibovsky","doi":"10.1007/s11012-024-01904-0","DOIUrl":"10.1007/s11012-024-01904-0","url":null,"abstract":"<div><p>We assess the suitability of Reynolds-Averaged Navier–Stokes (RANS) simulation using the Spalart-Allmaras (SA) turbulence model as a closure in analysing the performance of fluidic Active Flow Control (AFC) applications. In particular, we focus on the optimal set of actuation parameters found by Tousi et al. (Appl Math Model, 2021) and Tousi et al. (Aerospace Sci Technol 127:107679, 2022) for a SD7003 airfoil at a Reynolds number <span>(Re=6times 10^4)</span> and post-stall angle of attack <span>(alpha =14^circ)</span> fitted with a Synthetic Jet Actuator (SJA). The Large Eddy Simulation (LES) presented in that work is taken as the reference to identify the best choice of boundary conditions for the turbulence field <span>(tilde{nu })</span> at both domain inlet and jet orifice in two-dimensional SA-RANS computations. Although SA-RANS is far less accurate than LES, our findings show that it can still predict macroscopic aggregates such as lift and drag coefficients quite satisfactorily and at a much lower computational cost, provided that turbulence levels of the actuator jet are set to a realistic value. An adequate value of <span>(tilde{nu })</span> is instrumental in capturing the correct flow behaviour of the reattached boundary layers for close-to-optimal actuated cases. This validates the use of RANS-SA as a reliable and cost-effective simulation method for the preliminary optimisation of SJA parameters in AFC applications, provided that thorough sensitivity analysis on turbulence-related boundary conditions is performed. Given the strong sensitivity of flow detachment on the laminar or turbulent nature of boundary layers, our results suggest that such analyses are particularly indispensable for vastly separated flow scenarios in general, notably for bluff bodies at moderate transcritical Reynolds numbers.</p></div>","PeriodicalId":695,"journal":{"name":"Meccanica","volume":"59 12","pages":"2283 - 2294"},"PeriodicalIF":1.9,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11012-024-01904-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142906017","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of SFD on rubbing-induced vibration characteristics in dual-rotor-blade-casing system","authors":"Songtao Zhao,&nbsp;Ming Liu,&nbsp;Hui Ma,&nbsp;Hong Guan,&nbsp;Shan Chang,&nbsp;Xinxing Ma,&nbsp;Bangchun Wen","doi":"10.1007/s11012-024-01903-1","DOIUrl":"10.1007/s11012-024-01903-1","url":null,"abstract":"<div><p>In a dual-rotor (DR)-blade-casing system, the squeeze film damper (SFD) plays a crucial role in vibration suppression to reduce the vibration level. This paper investigates the impact of SFD on the vibration responses, specifically considering blade-casing rubbing. The Timoshenko beam element is employed to simulate the casing and rotor, while the blade and disk are established using the lumped-mass element. A dynamic model of the DR-blade-casing system with SFD is then developed, incorporating the effects of rubbing. The influence of parameters such as unbalance and blade-casing clearance on the dynamic response is analyzed for systems with and without SFD. The results indicate that SFD effectively reduces the amplitude of the characteristic frequency corresponding to 4-blade rubbing. Additionally, the rubbing fault also induces the combined frequencies between rotating frequencies, integer frequencies, and fractional frequencies. These findings offer valuable insights for fault diagnosis and aero-engine system design.</p></div>","PeriodicalId":695,"journal":{"name":"Meccanica","volume":"59 12","pages":"2265 - 2281"},"PeriodicalIF":1.9,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142905984","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Stability analysis of axially loaded sandwich beams with a five-layered composite core made of viscoelastic and functionally graded material layers","authors":"Satyajit Panda,&nbsp;Nitin Kumar","doi":"10.1007/s11012-024-01889-w","DOIUrl":"10.1007/s11012-024-01889-w","url":null,"abstract":"<div><p>In this paper, a five-layered viscoelastic composite laminate is proposed for the constrained layer damping (CLD) treatment of axially loaded beam structures. The CLD arrangement is taken in the conventional form of a sandwich beams. But, the main focus is to investigate the change in the static and dynamic stability characteristics of the axially loaded sandwich beam while the conventional pure viscoelastic core layer is replaced by the present five-layered composite laminate. First, the design of the five-layered composite laminate using three viscoelastic and two meatal-ceramic functionally graded (FG) material layers is presented. Next, an incremental nonlinear finite element model of the axially loaded sandwich beam is formulated based on the fractional Zener constitutive relation and harmonic balance method (HBM). The HBM is implemented with an arbitrary number of harmonic terms. The corresponding complexity in the formulation of the nonlinear system matrices/vectors is handled using a special factorization of the nonlinear strain–displacement matrix and an analytical time-integration strategy. The numerical results mainly illustrate the influence of the geometrical and graded material properties of the FG layers on the critical buckling load and damping in the axially loaded sandwich beam. These results reveal that the five-layered composite core provides not only an augmented damping for attenuation of vibration through the parametric resonance but also a significantly improved static stability of the axially loaded sandwich beam in comparison to the conventional pure viscoelastic core. Therefore, the present five-layer composite laminate may be a potential material for an improved CLD treatment of axially loaded beam structures.</p></div>","PeriodicalId":695,"journal":{"name":"Meccanica","volume":"59 12","pages":"2227 - 2263"},"PeriodicalIF":1.9,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142905997","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Design of a 6-supports exactly constrained supporting system for superconducting magnets and its application to rotating gantries for cancer therapy","authors":"Luca Piacentini,&nbsp;Luca Dassa,&nbsp;Diego Perini,&nbsp;Andris Ratkus,&nbsp;Toms Torims,&nbsp;Stefano Uberti","doi":"10.1007/s11012-024-01896-x","DOIUrl":"10.1007/s11012-024-01896-x","url":null,"abstract":"&lt;div&gt;&lt;p&gt;In particle therapy for cancer treatment, the radiation dose to tissues around the tumour can be reduced by employing a rotating gantry—a mechanical structure allowing the delivery of the particle beam to the patient from various angles. Gantries for ion therapy can benefit from the integration of superconducting magnets to minimize the size and weight of the machine. One significant challenge associated with the supporting system of superconducting elements is related to the management of their accuracy during both alignment and operational phases. Concurrently, heat flow from room temperature to cryogenic temperatures through the supporting system must be restricted as the ratio of power needed to operate the cooling system is around 1000 times the power extracted at cryogenic temperature. The design of the supports must consider the variability of the load during operation, i.e. guarantee accuracy of the cold-mass pose (position and rotation) under its own weight during a &lt;span&gt;({360,mathrm{ ^{circ }}})&lt;/span&gt; gantry rotation. A literature review had been done highlighting the possible application of a novel exact-constrained solution for the support of superconducting magnets. Within the framework of the European project HITRIplus (heavy Ion Therapy Research Integration), this study proposes the design and optimization of a support system based on a &lt;span&gt;(6)&lt;/span&gt; degrees of freedom parallel mechanism (exactly constrained kinematics). A mathematical model is proposed, referred as “error model”, to estimate the accuracy of the pose of the cold-mass due to major unrecoverable errors. The error model estimates the contribution of main error sources: the elasticity of the supports, the elasticity of the vacuum vessel enclosure and the influence of backlash in the joints. An optimization genetic algorithm has been developed and employed to find the optimal configuration of supports that simultaneously increases the accuracy and minimizes heat-loads to the cold-mass. The error model has been validated by finite element analysis, showing its validity for the optimization process. The optimised solution has been compared to solutions that were proposed initially based on common sense, intuition and had been manually refined: the optimized solution shows considerable improvements in the overall accuracy of the system and a substantial reduction of the heat-loads. The optimized solution also implements a pre-load system to eliminate backlash in the joints: this considerably improves the accuracy of the system. The error model presented allows computationally cheaper optimizations and variations of the designed architecture (i.e. variation in cross sections, change in material, change in geometry, implementation of pre-load etc...) with respect to a classic approach based only on finite element analysis. Furthermore, thanks to the kinematics characteristic of the proposed architecture, the 6-legs design clears the way for a more reliable imple","PeriodicalId":695,"journal":{"name":"Meccanica","volume":"59 12","pages":"2203 - 2226"},"PeriodicalIF":1.9,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11012-024-01896-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142905975","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Static and dynamic aspects of the principle of virtual work","authors":"Elżbieta Jarzębowska,&nbsp;Wiesław Grzesikiewicz,&nbsp;Michał Makowski,&nbsp;Artur Zbiciak,&nbsp;Katarzyna Rutczyńska-Wdowiak","doi":"10.1007/s11012-024-01897-w","DOIUrl":"10.1007/s11012-024-01897-w","url":null,"abstract":"<div><p>The paper presents a detailed analysis of the principle of virtual work in its statics and dynamics aspects. Special attention is paid to not exact formulation and interpretation of mechanical system motion equations based upon this principle, what is presented quite often in text books. The general form of the principle of virtual work and variational formulations of the problems in statics are presented and analyzed. Additionally, the dynamic implications of the principle of virtual work and dynamics problem formulation of a system subjected to scleronomic constraints are detailed. The basis for the formulation is the dynamic implication of the principle of virtual work that specifies the relation between the constraint reactions and the body accelerations. This relation takes the form of the variation inequality. As the result, the Gauss principle which determines the body acceleration vector is presented. Furthermore, a description of impact formulation, based upon the Carnot model, caused by the constraints is provided. The theoretical development is illustrated with examples of applications of the principle of virtual work.</p></div>","PeriodicalId":695,"journal":{"name":"Meccanica","volume":"59 12","pages":"2187 - 2202"},"PeriodicalIF":1.9,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11012-024-01897-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142906053","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}