Meccanica最新文献_第8页

A new theory of the dynamical collapse of no-tension structures under sequences of pulses of horizontal acceleration 无张力结构在水平加速度脉冲序列作用下的动力崩塌新理论

IF 2.1 3区工程技术

Meccanica Pub Date : 2025-03-25 DOI: 10.1007/s11012-025-01954-y

Simona Coccia, Mario Como

{"title":"A new theory of the dynamical collapse of no-tension structures under sequences of pulses of horizontal acceleration","authors":"Simona Coccia, Mario Como","doi":"10.1007/s11012-025-01954-y","DOIUrl":"10.1007/s11012-025-01954-y","url":null,"abstract":"<div><p>The paper presents the main lines of a new theory of the seismic dynamics of masonry structures in the context of the masonry Heyman model. The seismic action is represented by a sequence of horizontal acceleration pulses of rectangular shape, alternating in sign, of given intensity and wavelength. The central point of the proposed new theory is the definition of the way in which the dynamical collapse takes place, occurring during the motion of the no-tension structure, excited by the seismic shaking. Two new aspects play a fundamental role in this definition. The first is the configuration of zero strength, in which the potential energy of the weights reaches its maximum and where the structure has completely lost its strength. The second is the occurrence of the gradual accumulation of deformation of the structure that takes place under the pulse sequence, in spite of the alternating pulse action. Collapse thus takes place under the simultaneous achievement of the configuration of zero strength and the arrival of the acceleration pulse that pushes the structure to go beyond this configuration<i>.</i> By increasing the pulse number of the sequence, collapse takes place under smaller values of horizontal acceleration intensity. Finally, an asymptotic sequence of pulses allows an equation to be formulated for the behaviour factor (the ratio of collapse horizontal acceleration intensity to the static acceleration) for safe seismic design.</p></div>","PeriodicalId":695,"journal":{"name":"Meccanica","volume":"60 7","pages":"2033 - 2046"},"PeriodicalIF":2.1,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11012-025-01954-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144888086","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}

引用次数: 0

A slip-transpiration-vortex model for riblets past the viscous regime 越过粘性区域的小波纹的滑动-蒸腾-涡旋模型

IF 2.1 3区工程技术

Meccanica Pub Date : 2025-03-24 DOI: 10.1007/s11012-025-01962-y

Alessandro Bottaro, Giulia Innocenti, Essam Nabil Ahmed

引用次数: 0

Frequency response characteristics of the stereocilia tip-link tension in different regions of the cochlea 耳蜗不同区域立体纤毛尖端张力的频率响应特征

IF 1.9 3区工程技术

Meccanica Pub Date : 2025-03-22 DOI: 10.1007/s11012-024-01930-y

Jiakun Wang, Junyi Liang, Bin Liu, Wenjuan Yao

{"title":"Frequency response characteristics of the stereocilia tip-link tension in different regions of the cochlea","authors":"Jiakun Wang, Junyi Liang, Bin Liu, Wenjuan Yao","doi":"10.1007/s11012-024-01930-y","DOIUrl":"10.1007/s11012-024-01930-y","url":null,"abstract":"<div><p>Research on the mechanism of sound perception in the cochlea has always been an important challenge for scientists of humans. Therefore, the frequency response of stereocilia in the cochlear different regions and the changes in tip link tension was researched, which may deepen the understanding of the physiological role of stereocilia in relation to their biomechanical behaviours and the frequency encoding mechanism in the auditory system. In this paper, the stereocilia motion is described as a forced vibration structure, and the effect of the lymphatic fluid in the cochlea on the stereocilia is considered, and a stereocilia motion model is established. The tension distribution of the tip link at different frequencies was solved. The correctness of the model was proved by comparing the response frequencies of the tip links at different positions with the Greenwood frequency. An increase in the elastic modulus of stereocilia leads to a non-linear decrease in the tension of the tip link, while an increase in the elastic modulus of the tip link leads to an increase in the tension of the tip link. Reducing the proportion of low and medium stereocilia to high stereocilia helps to improve low frequency resolution. In addition, the height gradient of stereocilia has a significant impact on their frequency response characteristics, and there are significant differences in the resolution and response range of stereocilia in different rows of outer hair cells. There are significant differences in the frequency resolution capability and response range of stereocilia of outer hair cells in different rows.</p></div>","PeriodicalId":695,"journal":{"name":"Meccanica","volume":"60 4","pages":"911 - 925"},"PeriodicalIF":1.9,"publicationDate":"2025-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143896727","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}

引用次数: 0

Variations in wake structures and fluid forces around a square cylinder with four small control square rods at low Reynolds number 低雷诺数下带有四根小控制方杆的方形圆柱体周围尾流结构和流体力的变化

IF 1.9 3区工程技术

Meccanica Pub Date : 2025-03-22 DOI: 10.1007/s11012-025-01968-6

Salwa Fezai, Fakher Oueslati, Safa Mnefgui

{"title":"Variations in wake structures and fluid forces around a square cylinder with four small control square rods at low Reynolds number","authors":"Salwa Fezai, Fakher Oueslati, Safa Mnefgui","doi":"10.1007/s11012-025-01968-6","DOIUrl":"10.1007/s11012-025-01968-6","url":null,"abstract":"<div><p>Numerical prediction of fluid flow past a square cylinder with 4 control square rods placed in a channel is carried out using an in-house code based on finite volume method (FVM) and a full multi-grid technique (FMG). The flow features are extracted in terms of streamlines, iso-vortices, and drag (CD) and lift (CL) coefficients evolutions for steady and unsteady regimes. Numerical results demonstrated significant effect due to the addition of control rods by delaying the onset of flow instability, increasing the critical Reynolds number (Re<sub>c</sub>) from 50 to 80. For instance, at Re = 10, the flow around the square cylinder with control rods exhibits two large recirculation lobes, while higher Reynolds numbers lead to six elongated lobes. On another hand, at unsteady regime for the square cylinder without control rods, the critical Reynolds number for vortex shedding is predicted to be approximately 48.064. The flow remains steady up to Re ≈ 87 with control rods, transitioning to unsteady flow at Re ≈ 93, indicating a substantial delay compared to the cylinder without rods. It is also seen that oscillatory flow with rods is aperiodic, whereas it is periodic without rods. Moreover, the impact of control square rods on time averaged drag and lift coefficients is analyzed and discussed. It is found that Strouhal number (St) variation shows an enhancement up to Re ≈ 140 without rods, followed by a decline, while control rods lead to a drop in St despite increased frequencies. Additionally, drag coefficient is reduced by up to 58.31% with control rods, and lift coefficient peaks at Re = 1 without rods, declining with higher Re.</p></div>","PeriodicalId":695,"journal":{"name":"Meccanica","volume":"60 4","pages":"927 - 951"},"PeriodicalIF":1.9,"publicationDate":"2025-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143896728","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}

引用次数: 0

Composite control design for double-pendulum overhead cranes 双摆桥式起重机复合控制设计

IF 1.9 3区工程技术

Meccanica Pub Date : 2025-03-20 DOI: 10.1007/s11012-025-01961-z

Weiqiang Tang, Rui Ma, Hongmei Jiang, Haiyan Gao

{"title":"Composite control design for double-pendulum overhead cranes","authors":"Weiqiang Tang, Rui Ma, Hongmei Jiang, Haiyan Gao","doi":"10.1007/s11012-025-01961-z","DOIUrl":"10.1007/s11012-025-01961-z","url":null,"abstract":"<div><p>Eliminating or reducing swing and enhancing the robustness of closed-loop systems have always been hot issues in crane control research. To this end, a novel composite control strategy combining adaptive input shaper and double closed-loop PD feedback is proposed for double-pendulum overhead cranes. Firstly, based on the dynamic model of the double-pendulum system, an extremely insensitive input shaper acting on the acceleration signal is designed. The shaped signal can realize the direct adjustment of multiple stages of the trolley movement. Secondly, this input shaper is combined with double closed-loop PD control used for the displacement and the hook swing angle to form a novel composite control structure. This structure makes the closed-loop system robust against uncertainties. In order to further improve the adaptability of the control structure to complex working conditions, an adaptive input shaper optimization algorithm is proposed. The algorithm is based on a novel performance function that reflects the residual swing. The pulse amplitude and action time of the shaper can be adjusted online through iterative calculation of acceleration and hook swing angle. Finally, the results show that the proposed control strategy can reduce the swing angle and ensure the robustness of the system. In addition, compared with other control strategies of the same type, it performs better in swing suppression.</p></div>","PeriodicalId":695,"journal":{"name":"Meccanica","volume":"60 4","pages":"891 - 909"},"PeriodicalIF":1.9,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143896726","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}

引用次数: 0

A nonlinear iterative approach to predict large deflections of a novel spring-loaded ornithopter wing 一种预测新型弹簧翼大挠度的非线性迭代方法

IF 1.9 3区工程技术

Meccanica Pub Date : 2025-03-16 DOI: 10.1007/s11012-025-01944-0

Joydeep Bhowmik, Sriram Palika, Debopam Das

引用次数: 0

Manufacturing and characterization of compliant Cardan joints obtained by a new combined fabrication process 一种新型复合制造工艺制备柔顺万向关节及其特性

IF 2.1 3区工程技术

Meccanica Pub Date : 2025-03-15 DOI: 10.1007/s11012-025-01956-w

Marco Fava, Vincenzo Parenti-Castelli, Michele Conconi, Nicola Sancisi

引用次数: 0

Control-oriented modelling and analysis of transient rolling contact behaviour of tires 面向控制的轮胎瞬态滚动接触特性建模与分析

IF 1.9 3区工程技术

Meccanica Pub Date : 2025-03-12 DOI: 10.1007/s11012-025-01960-0

Yingjie Zhu, Jianwei Lu, Ping Jiang

引用次数: 0

Free vibration analysis of functionally graded carbon nanotube-reinforced beams with variable cross-section using the differential transform method 变截面功能梯度碳纳米管增强梁的自由振动分析

IF 2.1 3区工程技术

Meccanica Pub Date : 2025-03-11 DOI: 10.1007/s11012-025-01952-0

Vyacheslav N. Burlayenko, Tomasz Sadowski, Liviu Marsavina

{"title":"Free vibration analysis of functionally graded carbon nanotube-reinforced beams with variable cross-section using the differential transform method","authors":"Vyacheslav N. Burlayenko, Tomasz Sadowski, Liviu Marsavina","doi":"10.1007/s11012-025-01952-0","DOIUrl":"10.1007/s11012-025-01952-0","url":null,"abstract":"<div><p>The paper studies the free vibration of carbon nanotube-reinforced composite (CNTRC) beams with variable cross-sections. The carbon nanotubes embedded in a polymeric matrix are assumed to be functionally graded (FG) across the beam’s thickness, with their material properties determined using the rule of mixtures. Various CNT distribution patterns and cross-sectional variation profiles are considered. The study employs Timoshenko beam theory, deriving the governing equations via Hamilton’s principle. These differential equations with variable coefficients are solved using the differential transform method (DTM), which is formulated as a unified eigenvalue problem applicable to various boundary conditions. The computed results are validated against available literature to ensure accuracy and reliability. Subsequently, a comprehensive parametric study examines the influence of geometrical and material parameters on the vibration behavior of FG-CNTRC beams. The findings reveal that natural frequencies are significantly affected by taper parameters, CNT content, and nanotube distribution patterns. Finally, the study identifies the CNT distributions that offer the most favorable vibration characteristics.</p></div>","PeriodicalId":695,"journal":{"name":"Meccanica","volume":"60 8","pages":"2361 - 2388"},"PeriodicalIF":2.1,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145230370","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}

引用次数: 0

Multipolar wind distributions 多极风分布

IF 2.1 3区工程技术

Meccanica Pub Date : 2025-03-07 DOI: 10.1007/s11012-024-01908-w

Andrea Pedrini, Epifanio G. Virga, Andrea Marziali, Anna Malagó

引用次数: 0