Comptes Rendus Mecanique最新文献

The Meyer’s estimate of solutions to Zaremba problem for second-order elliptic equations in divergent form 二阶发散型椭圆方程Zaremba问题解的Meyer估计

IF 0.8 4区工程技术

Comptes Rendus Mecanique Pub Date : 2021-06-07 DOI: 10.5802/CRMECA.87

Yu. A. Alkhutov, G. Chechkin

引用次数: 4

2D model simulating the hydro-rheological behavior of leather during convective drying 模拟皮革在对流干燥过程中流体流变特性的二维模型

IF 0.8 4区工程技术

Comptes Rendus Mecanique Pub Date : 2021-06-07 DOI: 10.5802/CRMECA.86

Naima Benmakhlouf, S. Azzouz, L. Hassini, A. Cafsi

{"title":"2D model simulating the hydro-rheological behavior of leather during convective drying","authors":"Naima Benmakhlouf, S. Azzouz, L. Hassini, A. Cafsi","doi":"10.5802/CRMECA.86","DOIUrl":"https://doi.org/10.5802/CRMECA.86","url":null,"abstract":"An experimental and numerical study of a two-dimensional spatio-temporal variation of the temperature, moisture content, and mechanical stress during the convective drying process of unsaturated and deformable products (leather) were conducted. The bovine leather sample response under convective drying is described by a mathematical model. The leather sample was modeled by an elastic medium, and the mass, heat, and momentum transfer principles are applied. The numerical results agreed well with the corresponding experimental data. The variation of the internal temperature and moisture content was simulated for different drying conditions. A reduction by 15 °C was noted in the optimum temperature for best product quality when the drying air relative humidity was 20%. The cost to achieve a better quality product was found to be minimized due to the decrease in the optimum temperature. The presented simulation results of the elastic material could be applied to the leather, which will reduce the needed time of exposure for predetermined final water content. The damage of the sample is more likely to occur at the beginning of the drying in the time interval of 300–400 s. According to these simulations, the sample’s face, which is exposed to the drying air, has the highest stress; therefore, the sample’s face is at a high risk of cracking. It is also observed that the risk of damage to the sample corresponding to the maximum level of the stress is higher for the highest drying temperature of 60 °C. The peak of the three thicknesses of leather can be achieved for normal stresses in the interval of 60,000 to 140,000 MPa at around 10,000 s.","PeriodicalId":50997,"journal":{"name":"Comptes Rendus Mecanique","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2021-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82033049","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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

Modal energetic analysis and dynamic response of worm gear drives with a new developed dynamic model 基于新建立的蜗轮传动动力学模型的模态能量分析与动态响应

IF 0.8 4区工程技术

Comptes Rendus Mecanique Pub Date : 2021-05-03 DOI: 10.5802/CRMECA.80

Ala Eddin Chakroun, A. Hammami, A. De-Juan, F. Chaari, Alfonso Fernández, F. Viadero, M. Haddar

引用次数: 5

Impact of the fracture contact area on macro-dispersion in single rough fractures 裂缝接触面积对单个粗裂缝宏观弥散的影响

IF 0.8 4区工程技术

Comptes Rendus Mecanique Pub Date : 2021-04-27 DOI: 10.5802/CRMECA.82

A. Beaudoin, M. Farhat

{"title":"Impact of the fracture contact area on macro-dispersion in single rough fractures","authors":"A. Beaudoin, M. Farhat","doi":"10.5802/CRMECA.82","DOIUrl":"https://doi.org/10.5802/CRMECA.82","url":null,"abstract":"In the scientific literature, the study of the impact of the fracture contact area on macro-dispersion in single rough fractures is still an open question. In this work, we study numerically the combined effects of the fracture roughness and the fracture contact area on the non-Fickian transport in single rough fractures. In particular, we quantify the contribution of the fracture contact area on macro-dispersion. These objectives are achieved by estimating the macro-dispersion coefficient from Monte Carlo parallel numerical simulations in pure advection and advection–diffusion cases. When the fractional void SO is equal to 1 (i.e., for σlnb < 0.25), the Monte Carlo simulations show that macro-dispersion results of two contributions, dispersion caused by the heterogeneity of fracture apertures that induces a channelization of flow paths and molecular diffusion, as shown by the analytical solution proposed by Gelhar in 1993. When the fraction void SO is different from 1 (i.e., forσlnb > 0.25), a third mechanism plays in macro-dispersion. The presence of contacts or obstacles causes a disruption of flow paths. This mechanism is identical to that induced by the fracture roughness with a lower amplitude. Its amplitude is the function of the fractional void SO .","PeriodicalId":50997,"journal":{"name":"Comptes Rendus Mecanique","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2021-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78726435","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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: 1

Indicator kriging for damage position prediction by the use of electromechanical impedance-based structural health monitoring 基于机电阻抗的结构健康监测损伤位置预测指标克里格法

IF 0.8 4区工程技术

Comptes Rendus Mecanique Pub Date : 2021-04-27 DOI: 10.5802/CRMECA.81

Daniel Resende Gonçalves, Jose dos Reis Vieira de Moura, Paulo Pereira, Marcos Vinícius Agapito Mendes, Henrique Senna Diniz-Pinto

{"title":"Indicator kriging for damage position prediction by the use of electromechanical impedance-based structural health monitoring","authors":"Daniel Resende Gonçalves, Jose dos Reis Vieira de Moura, Paulo Pereira, Marcos Vinícius Agapito Mendes, Henrique Senna Diniz-Pinto","doi":"10.5802/CRMECA.81","DOIUrl":"https://doi.org/10.5802/CRMECA.81","url":null,"abstract":"Some nondestructive techniques of the Structural Health Monitoring (SHM) have improved their analysis in the past decades. Among them, the electromechanical impedance-based SHM technique (EMISHM) has been tested in several fields and associated to different statistical methodologies. Considering the nature of the spatial variation of the damage metric data along structures, herein is proposed the use of the indicator kriging method for predicting the existence of a known damage located in the center of an aluminum plate. Maps showing the probability of the damage metric to fall in several value ranges were capable of outlining the areas affected by the damage and predict its location. Comparisons between scenarios with different spacing between PZT patches showed a reduction in the reliability of the model with the increasing of such spacing. Also, for the structure under study, it demonstrates that it is not possible to obtain results by the methodology for distance between sensors/actuators greater than 16.67 cm. However, the results show that this approach can be a viable alternative for using damage metrics to map regions affected by damage and its location.","PeriodicalId":50997,"journal":{"name":"Comptes Rendus Mecanique","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2021-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82001062","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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: 1

CFD analysis of operating condition effects on optimum nozzle exit position of a supersonic ejector using the refrigerant R134a 采用R134a制冷剂的超声速引射器工况对喷口最佳出口位置影响的CFD分析

IF 0.8 4区工程技术

Comptes Rendus Mecanique Pub Date : 2021-04-14 DOI: 10.5802/crmeca.60

A. Hadj, M. Boulenouar

引用次数: 1

Correlation between the toroidal modes of an elastic sphere and the viscosity of liquids 弹性球的环面模态与液体粘度的关系

IF 0.8 4区工程技术

Comptes Rendus Mecanique Pub Date : 2021-03-26 DOI: 10.5802/CRMECA.79

J. L. Pommellec, A. E. Baroudi

引用次数: 0

Fractional stress-dilatancy equation based on critical state lines with arbitrary form 基于任意形式临界状态线的分数阶应力-剪胀方程

IF 0.8 4区工程技术

Comptes Rendus Mecanique Pub Date : 2021-03-17 DOI: 10.5802/CRMECA.78

Yifei Sun, Jiancheng Zhang

引用次数: 1

Correspondence between de Saint-Venant and Boussinesq 5: Viscosity and hydraulic resistance 圣维南与布西内斯克的对应关系5:粘度和水力阻力

IF 0.8 4区工程技术

Comptes Rendus Mecanique Pub Date : 2021-03-17 DOI: 10.5802/CRMECA.71

W. Hager, K. Hutter, O. Castro-Orgaz

{"title":"Correspondence between de Saint-Venant and Boussinesq 5: Viscosity and hydraulic resistance","authors":"W. Hager, K. Hutter, O. Castro-Orgaz","doi":"10.5802/CRMECA.71","DOIUrl":"https://doi.org/10.5802/CRMECA.71","url":null,"abstract":"Fluid viscosity is a main feature of fluids; an inviscid fluid does not exist even though a large number of theories has been advanced for flows of such fluids. The velocity of fluid flow may considerably be reduced due to the presence of fluid viscosity both for laminar and turbulent flows. The letters exchanged between de Saint-Venant (dSV) and Boussinesq mainly refer to laminar flow. The most peculiar statement of dSV is that, if the flow in a typical lowland river would be laminar, its velocity would be larger than the speed of sound. It is evident that this statement is wrong because laminar flow has stringent limitations typically expressed by the Reynolds number. The hydraulic resistance is another peculiar feature in hydrodynamics, given that several theories have been advanced which do not at all reflect the everyday experience. One of these is the d’Alembert paradox, stating that the resistance is equal to zero for a steady flow of an inviscid and incompressible fluid. Typically, a body suspended in a large pipe is considered. Applying the momentum equation in the axial direction sufficiently upand downstream of the body, the resistance would indeed become zero, as occurs for potential flows. Again, this is far away from everybody’s experience, such as for a swimmer or a walker under heavy","PeriodicalId":50997,"journal":{"name":"Comptes Rendus Mecanique","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2021-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87683992","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 hybrid piezoelectric–electromagnetic nonlinear vibration energy harvester excited by fluid flow 一种流体激励下的压电-电磁混合非线性振动能量采集器

IF 0.8 4区工程技术

Comptes Rendus Mecanique Pub Date : 2021-03-04 DOI: 10.5802/CRMECA.74

M. Hafizh, A. Muthalif, J. Renno, M. R. Paurobally, M. Arab, I. Bahadur, H. Ouakad

{"title":"A hybrid piezoelectric–electromagnetic nonlinear vibration energy harvester excited by fluid flow","authors":"M. Hafizh, A. Muthalif, J. Renno, M. R. Paurobally, M. Arab, I. Bahadur, H. Ouakad","doi":"10.5802/CRMECA.74","DOIUrl":"https://doi.org/10.5802/CRMECA.74","url":null,"abstract":"Energy harvesting mechanisms can be used to extract energy from ambient surroundings to power small electronic devices, which has a significant advantage in realizing self-sustaining wireless devices. The proposed design of this study uses the internal fluid flow within a pipe and takes advantage of the fluid– structure interaction through flow-induced vibration of a bluff body. The hybrid harvester uses the vibration to convert electrical energy through a piezoelectric material and an electromagnetic oscillator that can be tuned to resonate at the oscillation frequency. A numerical solver was used to estimate harvestable voltage for this submerged hybrid energy harvester model by using ordinary differential equations. A computational study was used to optimize the performance of the bluffbodies under the influence of the vortices for circular, triangular, ellipse, and quadrilateral shapes. Wake development was seen in the circular and triangular shapes with the ellipse having the lowest turbulence kinetic energy among the shapes. Structural deflection of the beam under resonance was compared for the different shapes, which displayed better results for triangular and elliptical bluff bodies.","PeriodicalId":50997,"journal":{"name":"Comptes Rendus Mecanique","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2021-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85560492","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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: 8