Pub Date : 2025-11-06DOI: 10.1016/j.ijengsci.2025.104418
M.B. Rubin
An Eulerian formulation of a size-dependent three-dimensional Cosserat continuum is developed for purely mechanical response of an anisotropic non-Newtonian viscous Cosserat fluid. The constitutive equations are Eulerian in the sense that they depend only on quantities that can be determined in the current state of the fluid. The Cosserat theory admits a triad of linearly independent deformable directors vectors at each material point, which are determined by higher-order balances of director momentum. It is shown that the balance of angular momentum of the Cosserat fluid imposes a non-trivial restriction on coupling between kinetic and kinematic variables that is satisfied by the proposed constitutive equations. An analytical solution of anisotropic Newtonian viscous fluid flow in a channel demonstrates size-dependence of the pressure driving the flow that is not present in the standard solution of a simple viscous fluid.
{"title":"An Eulerian formulation of a size-dependent anisotropic non-Newtonian viscous Cosserat fluid","authors":"M.B. Rubin","doi":"10.1016/j.ijengsci.2025.104418","DOIUrl":"10.1016/j.ijengsci.2025.104418","url":null,"abstract":"<div><div>An Eulerian formulation of a size-dependent three-dimensional Cosserat continuum is developed for purely mechanical response of an anisotropic non-Newtonian viscous Cosserat fluid. The constitutive equations are Eulerian in the sense that they depend only on quantities that can be determined in the current state of the fluid. The Cosserat theory admits a triad of linearly independent deformable directors vectors at each material point, which are determined by higher-order balances of director momentum. It is shown that the balance of angular momentum of the Cosserat fluid imposes a non-trivial restriction on coupling between kinetic and kinematic variables that is satisfied by the proposed constitutive equations. An analytical solution of anisotropic Newtonian viscous fluid flow in a channel demonstrates size-dependence of the pressure driving the flow that is not present in the standard solution of a simple viscous fluid.</div></div>","PeriodicalId":14053,"journal":{"name":"International Journal of Engineering Science","volume":"218 ","pages":"Article 104418"},"PeriodicalIF":5.7,"publicationDate":"2025-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145463872","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-06DOI: 10.1016/j.ijengsci.2025.104407
Yuntang Li, Zhitong Sun, Cong Zhang, Jie Jin, Yuan Chen, Bingqing Wang, Juan Feng
An aerostatic thrust bearing lubricated by supercritical carbon dioxide (ATB-SCO2) is ideal axial support component for the rotating shaft of an SCO2 cycle power generator. However, little literature is related to the performance analysis of an ATB-SCO2 and laminar model is commonly used, leading to significant errors in bearing performance predictions. In this article, the modified Reynolds equation based on Elrod-Ng turbulence model and orifice discharge equation are combined and solved by finite difference method for calculating the static performance of an ATB-SCO2. Moreover, the turbulence effect on ATB-SCO2 static performance is investigated by analyzing the flow field characteristics in lubricating film. The results indicate that SCO2 on thrust plate is in a turbulent state. Load capacity and stiffness calculated by turbulence model are larger while mass flow rate is lower compared to those of obtained by laminar model. The fluid velocity varies steeply near-wall and smoothly in middle of lubricating film due to the increased effective viscosity in middle of lubricating film. Load capacity and stiffness increase with the increase of supply pressure and rotational speed, and decrease with the growth of film thickness. Furthermore, the static performance of an ATB-SCO2 is significantly influenced by pressure-equalizing groove depth (when the depth is <50 µm) and restrictor number, and the effects of pressure-equalizing groove width can be neglected.
{"title":"Performance analysis of an aerostatic thrust bearing lubricated by supercritical CO2 utilizing Elrod-Ng turbulence model","authors":"Yuntang Li, Zhitong Sun, Cong Zhang, Jie Jin, Yuan Chen, Bingqing Wang, Juan Feng","doi":"10.1016/j.ijengsci.2025.104407","DOIUrl":"10.1016/j.ijengsci.2025.104407","url":null,"abstract":"<div><div>An aerostatic thrust bearing lubricated by supercritical carbon dioxide (ATB-SCO<sub>2</sub>) is ideal axial support component for the rotating shaft of an SCO<sub>2</sub> cycle power generator. However, little literature is related to the performance analysis of an ATB-SCO<sub>2</sub> and laminar model is commonly used, leading to significant errors in bearing performance predictions. In this article, the modified Reynolds equation based on Elrod-Ng turbulence model and orifice discharge equation are combined and solved by finite difference method for calculating the static performance of an ATB-SCO<sub>2</sub>. Moreover, the turbulence effect on ATB-SCO<sub>2</sub> static performance is investigated by analyzing the flow field characteristics in lubricating film. The results indicate that SCO<sub>2</sub> on thrust plate is in a turbulent state. Load capacity and stiffness calculated by turbulence model are larger while mass flow rate is lower compared to those of obtained by laminar model. The fluid velocity varies steeply near-wall and smoothly in middle of lubricating film due to the increased effective viscosity in middle of lubricating film. Load capacity and stiffness increase with the increase of supply pressure and rotational speed, and decrease with the growth of film thickness. Furthermore, the static performance of an ATB-SCO<sub>2</sub> is significantly influenced by pressure-equalizing groove depth (when the depth is <50 µm) and restrictor number, and the effects of pressure-equalizing groove width can be neglected.</div></div>","PeriodicalId":14053,"journal":{"name":"International Journal of Engineering Science","volume":"218 ","pages":"Article 104407"},"PeriodicalIF":5.7,"publicationDate":"2025-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145463871","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-06DOI: 10.1016/j.ijengsci.2025.104415
Mani Reddipaga , K. Kannan
Human brain tissue exhibits a nonlinear viscoelastic response characterised by relaxation, creep, and loading-rate dependence. Under quasi-static conditions, its elastic behaviour shows pronounced tension–compression asymmetry and greater shear stiffness in compression than in tension under combined loading. Capturing these features with fewer parameters remains a challenge. To ensure physical consistency, isotropic hyperelastic models are required to satisfy the Baker–Ericksen (B–E) inequalities. Leveraging the physical interpretation of Lode invariants, we construct a stored energy function through a priori analysis of B–E inequalities, achieving maximal tension–compression asymmetry by satisfying these inequalities. The resulting two-parameter stored energy function is benchmarked against existing models using the nonlinear shear modulus and Mooney’s asymmetry function under uniaxial deformation. Among these, the proposed model yields a correct bounded response consistent with experimental brain tissue data. The model is then extended to viscoelasticity using K.R. Rajagopal’s thermodynamic approach, where the viscoelastic constitutive equations are derived from the two scalar functions: the stored energy and the rate of dissipation. The developed stored energy is employed for both equilibrium and non-equilibrium contributions, and a simple quadratic dissipation function is chosen. Constitutive equations are derived by extremizing the rate of dissipation function subject to constraints such as incompressibility and the second law of thermodynamics. Validation against experimental data of Budday et al. (2017) shows that the proposed four-parameter model captures key mechanical features of brain tissue, including tension–compression asymmetry, hysteresis, and relaxation, while showing closer agreement than the six-parameter Budday–Ogden model for shear superposed on tension/compression deformation.
{"title":"On the construction of a viscoelastic constitutive model for brain tissue maximizing tension–compression asymmetry","authors":"Mani Reddipaga , K. Kannan","doi":"10.1016/j.ijengsci.2025.104415","DOIUrl":"10.1016/j.ijengsci.2025.104415","url":null,"abstract":"<div><div>Human brain tissue exhibits a nonlinear viscoelastic response characterised by relaxation, creep, and loading-rate dependence. Under quasi-static conditions, its elastic behaviour shows pronounced tension–compression asymmetry and greater shear stiffness in compression than in tension under combined loading. Capturing these features with fewer parameters remains a challenge. To ensure physical consistency, isotropic hyperelastic models are required to satisfy the Baker–Ericksen (B–E) inequalities. Leveraging the physical interpretation of Lode invariants, we construct a stored energy function through a priori analysis of B–E inequalities, achieving maximal tension–compression asymmetry by satisfying these inequalities. The resulting two-parameter stored energy function is benchmarked against existing models using the nonlinear shear modulus and Mooney’s asymmetry function under uniaxial deformation. Among these, the proposed model yields a correct bounded response consistent with experimental brain tissue data. The model is then extended to viscoelasticity using K.R. Rajagopal’s thermodynamic approach, where the viscoelastic constitutive equations are derived from the two scalar functions: the stored energy and the rate of dissipation. The developed stored energy is employed for both equilibrium and non-equilibrium contributions, and a simple quadratic dissipation function is chosen. Constitutive equations are derived by extremizing the rate of dissipation function subject to constraints such as incompressibility and the second law of thermodynamics. Validation against experimental data of Budday et al. (2017) shows that the proposed four-parameter model captures key mechanical features of brain tissue, including tension–compression asymmetry, hysteresis, and relaxation, while showing closer agreement than the six-parameter Budday–Ogden model for shear superposed on tension/compression deformation.</div></div>","PeriodicalId":14053,"journal":{"name":"International Journal of Engineering Science","volume":"218 ","pages":"Article 104415"},"PeriodicalIF":5.7,"publicationDate":"2025-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145461733","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-06DOI: 10.1016/j.ijengsci.2025.104406
Ning Cao , Tongtong Liu , Xingchen Chen , Ying Wu , Xiang Li
Mechanical metamaterials have attracted extensive attention for their unconventional mechanical responses. Among them, compression-twist (CT) materials introduce new opportunities for programmable mechanical behavior. However, achieving continuous control of stiffness and Poisson’s ratio over wide ranges remains challenging. While negative Poisson’s ratio (NPR) metamaterials have been widely explored for their auxetic effects, their tunability and multi-physical performance are still limited. Here, we design four three-dimensional (3D) mechanical metamaterials—CT-NPR, CT-positive Poisson’s ratio (CT-PPR), augmented CT (ACT)-NPR, and ACT-PPR—by combining CT and NPR architectures. These structures exhibit tunable Poisson’s ratios and stiffness spanning over an extremely wide range. Numerical simulations and theoretical analysis reveal that CT-NPR and CT-PPR are bending-dominated with low stiffness, whereas ACT-NPR and ACT-PPR are stretching-dominated with high stiffness. Then, the metamaterials are fabricated via 3D printing, and their mechanical properties are characterized using quasi-static compression tests. Experimental results are consistent with theoretical predictions, confirming NPR behavior in CT-NPR and ACT-NPR, and positive Poisson’s ratio behavior in CT-PPR and ACT-PPR. Additionally, CT-PPR exhibits a distinctive two-step deformation process without self-contact, while energy absorption studies show that ACT-NPR achieves superior energy dissipation and CT-PPR maintains a stable deformation mode. This work provides a new framework for designing programmable mechanical metamaterials with potential applications in shape-morphing devices, energy absorbers, medical instruments, smart actuators, and crashworthy structures.
{"title":"Compression-twist induced 3D mechanical metamaterial with programmable mechanical properties","authors":"Ning Cao , Tongtong Liu , Xingchen Chen , Ying Wu , Xiang Li","doi":"10.1016/j.ijengsci.2025.104406","DOIUrl":"10.1016/j.ijengsci.2025.104406","url":null,"abstract":"<div><div>Mechanical metamaterials have attracted extensive attention for their unconventional mechanical responses. Among them, compression-twist (CT) materials introduce new opportunities for programmable mechanical behavior. However, achieving continuous control of stiffness and Poisson’s ratio over wide ranges remains challenging. While negative Poisson’s ratio (NPR) metamaterials have been widely explored for their auxetic effects, their tunability and multi-physical performance are still limited. Here, we design four three-dimensional (3D) mechanical metamaterials—CT-NPR, CT-positive Poisson’s ratio (CT-PPR), augmented CT (ACT)-NPR, and ACT-PPR—by combining CT and NPR architectures. These structures exhibit tunable Poisson’s ratios and stiffness spanning over an extremely wide range. Numerical simulations and theoretical analysis reveal that CT-NPR and CT-PPR are bending-dominated with low stiffness, whereas ACT-NPR and ACT-PPR are stretching-dominated with high stiffness. Then, the metamaterials are fabricated via 3D printing, and their mechanical properties are characterized using quasi-static compression tests. Experimental results are consistent with theoretical predictions, confirming NPR behavior in CT-NPR and ACT-NPR, and positive Poisson’s ratio behavior in CT-PPR and ACT-PPR. Additionally, CT-PPR exhibits a distinctive two-step deformation process without self-contact, while energy absorption studies show that ACT-NPR achieves superior energy dissipation and CT-PPR maintains a stable deformation mode. This work provides a new framework for designing programmable mechanical metamaterials with potential applications in shape-morphing devices, energy absorbers, medical instruments, smart actuators, and crashworthy structures.</div></div>","PeriodicalId":14053,"journal":{"name":"International Journal of Engineering Science","volume":"218 ","pages":"Article 104406"},"PeriodicalIF":5.7,"publicationDate":"2025-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145448081","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-04DOI: 10.1016/j.ijengsci.2025.104403
S. El-Borgi , M. Trabelssi , N. Challamel , J.N. Reddy
This study develops a rigorous analytical framework for investigating the static bending behavior of micromorphic and nonlocal strain gradient Timoshenko beams, with particular emphasis on capturing size-dependent effects in micro- and nano-scale structural elements. The model is derived using a variational principle and it consists of a set of governing equations and boundary conditions that incorporate two distinct internal length-scales, one associated with nonlocal stress gradients and the other with strain gradient effects. The obtained system of two coupled differential equations governs the deflection and the rotation of the beam. Uncoupling both equations leads to sixth- and fifth-order differential equations for the deflection and the rotation, respectively. Exact solutions are obtained for standard boundary configurations, including simply-supported, clamped–clamped, and cantilever cases, under both point and distributed loads. The analytical model is shown to be theoretically equivalent to a class of two-length-scale nonlocal strain gradient theories, thereby offering a consistent and unified description of scale-dependent mechanics in microstructured beams. A distinct series-based solution is also constructed to verify the closed-form micromorphic results. Verification against established reference solutions demonstrates the accuracy and generality of the proposed model. A series of parametric studies is conducted to quantify the role of internal length-scales, revealing that the model successfully predicts both stiffening and softening trends, depending on the microstructural configuration. The derived exact solutions provide a reliable benchmark for assessing numerical schemes and serve as a foundation for further studies involving advanced materials with microstructural complexity.
{"title":"Static bending of micromorphic Timoshenko beams","authors":"S. El-Borgi , M. Trabelssi , N. Challamel , J.N. Reddy","doi":"10.1016/j.ijengsci.2025.104403","DOIUrl":"10.1016/j.ijengsci.2025.104403","url":null,"abstract":"<div><div>This study develops a rigorous analytical framework for investigating the static bending behavior of micromorphic and nonlocal strain gradient Timoshenko beams, with particular emphasis on capturing size-dependent effects in micro- and nano-scale structural elements. The model is derived using a variational principle and it consists of a set of governing equations and boundary conditions that incorporate two distinct internal length-scales, one associated with nonlocal stress gradients and the other with strain gradient effects. The obtained system of two coupled differential equations governs the deflection and the rotation of the beam. Uncoupling both equations leads to sixth- and fifth-order differential equations for the deflection and the rotation, respectively. Exact solutions are obtained for standard boundary configurations, including simply-supported, clamped–clamped, and cantilever cases, under both point and distributed loads. The analytical model is shown to be theoretically equivalent to a class of two-length-scale nonlocal strain gradient theories, thereby offering a consistent and unified description of scale-dependent mechanics in microstructured beams. A distinct series-based solution is also constructed to verify the closed-form micromorphic results. Verification against established reference solutions demonstrates the accuracy and generality of the proposed model. A series of parametric studies is conducted to quantify the role of internal length-scales, revealing that the model successfully predicts both stiffening and softening trends, depending on the microstructural configuration. The derived exact solutions provide a reliable benchmark for assessing numerical schemes and serve as a foundation for further studies involving advanced materials with microstructural complexity.</div></div>","PeriodicalId":14053,"journal":{"name":"International Journal of Engineering Science","volume":"218 ","pages":"Article 104403"},"PeriodicalIF":5.7,"publicationDate":"2025-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145435048","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-03DOI: 10.1016/j.ijengsci.2025.104404
A. Vattré , Z. Zhang , E. Pan
A unified dislocation-based framework is developed for the three-dimensional analysis of internal and horizontal penny-shaped cracks embedded in multilayered transversely isotropic half-spaces. The proposed formulation covers all three classical fracture modes I, II, and III, while accounting for elastic mismatch, crack depth, and imperfect interfacial contact within arbitrary layup stacking sequences. The fundamental Green’s solutions, corresponding to the elastic response induced by continuous distributions of unit-concentrated dislocation sources, are expanded using a Fourier–Bessel series system of vector functions composed of longitudinal, gradient-type meridional, and curl-type torsional modal fields. This modal decomposition establishes a canonical correspondence between fracture modes and basis components, thereby enabling mixed-mode representations by linear superposition. The displacement field is represented by spectral Love-type expansion coefficients, where the Love numbers are computed only once. The unknown displacement discontinuity is discretized using a ring-wise collocation method and subsequently determined to satisfy the prescribed crack-face loading for each fracture mode. By means of the dual-variable and position technique, recursive layer-by-layer propagation schemes are constructed to ensure internal continuity conditions and to incorporate imperfect contact through normal and tangential interfacial springs, leading to stable and fast convergence for multilayered structures. Stress intensity factors and energy release rates are extracted by matching the near-tip asymptotic behavior of the displacement discontinuity, showing excellent agreement with benchmark reference solutions, and further extending to depth-dependent mode I, II, III, and mixed-mode fracture in layered configurations. The capabilities of the formulation are illustrated by examining titanium-based multilayer systems under mode I loading. The contrast between stiff and soft gradient-layered configurations reveals how stiffness variation and interfacial compliance modulate both stress concentration and crack-face separation. The soft gradient architecture, while producing a greater crack opening, yields a reduced normalized mode I stress intensity factor compared to the stiff layered configuration. The analysis emphasizes symmetry deviations, fracture-mode-dependent discontinuities, and the localized nature of displacement and stress fields. The results provide insight into internal fracture phenomena in coated structures, layered ceramics, and stratified functional materials, and support the design of multilayer systems with improved durability and damage tolerance.
{"title":"A spectral dislocation-based framework for 3D internal fracture in layered transversely isotropic half-spaces with imperfect interfaces","authors":"A. Vattré , Z. Zhang , E. Pan","doi":"10.1016/j.ijengsci.2025.104404","DOIUrl":"10.1016/j.ijengsci.2025.104404","url":null,"abstract":"<div><div>A unified dislocation-based framework is developed for the three-dimensional analysis of internal and horizontal penny-shaped cracks embedded in multilayered transversely isotropic half-spaces. The proposed formulation covers all three classical fracture modes I, II, and III, while accounting for elastic mismatch, crack depth, and imperfect interfacial contact within arbitrary layup stacking sequences. The fundamental Green’s solutions, corresponding to the elastic response induced by continuous distributions of unit-concentrated dislocation sources, are expanded using a Fourier–Bessel series system of vector functions composed of longitudinal, gradient-type meridional, and curl-type torsional modal fields. This modal decomposition establishes a canonical correspondence between fracture modes and basis components, thereby enabling mixed-mode representations by linear superposition. The displacement field is represented by spectral Love-type expansion coefficients, where the Love numbers are computed only once. The unknown displacement discontinuity is discretized using a ring-wise collocation method and subsequently determined to satisfy the prescribed crack-face loading for each fracture mode. By means of the dual-variable and position technique, recursive layer-by-layer propagation schemes are constructed to ensure internal continuity conditions and to incorporate imperfect contact through normal and tangential interfacial springs, leading to stable and fast convergence for multilayered structures. Stress intensity factors and energy release rates are extracted by matching the near-tip asymptotic behavior of the displacement discontinuity, showing excellent agreement with benchmark reference solutions, and further extending to depth-dependent mode I, II, III, and mixed-mode fracture in layered configurations. The capabilities of the formulation are illustrated by examining titanium-based multilayer systems under mode I loading. The contrast between stiff and soft gradient-layered configurations reveals how stiffness variation and interfacial compliance modulate both stress concentration and crack-face separation. The soft gradient architecture, while producing a greater crack opening, yields a reduced normalized mode I stress intensity factor compared to the stiff layered configuration. The analysis emphasizes symmetry deviations, fracture-mode-dependent discontinuities, and the localized nature of displacement and stress fields. The results provide insight into internal fracture phenomena in coated structures, layered ceramics, and stratified functional materials, and support the design of multilayer systems with improved durability and damage tolerance.</div></div>","PeriodicalId":14053,"journal":{"name":"International Journal of Engineering Science","volume":"218 ","pages":"Article 104404"},"PeriodicalIF":5.7,"publicationDate":"2025-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145427962","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-23DOI: 10.1016/j.ijengsci.2025.104398
P.A. Martin
Eringen’s original linear theory of nonlocal elasticity involves integral operators. We apply a modified version of this theory to the problem of waves in an elastic half-space. The modification ensures that the traction-free conditions on the flat boundary are incorporated into the choice of kernels in the integral operators. We solve the governing equations exactly and show that the resulting solutions do not represent surface waves.
{"title":"Rayleigh waves within Eringen’s nonlocal elasticity theory: Use of modified kernels","authors":"P.A. Martin","doi":"10.1016/j.ijengsci.2025.104398","DOIUrl":"10.1016/j.ijengsci.2025.104398","url":null,"abstract":"<div><div>Eringen’s original linear theory of nonlocal elasticity involves integral operators. We apply a modified version of this theory to the problem of waves in an elastic half-space. The modification ensures that the traction-free conditions on the flat boundary are incorporated into the choice of kernels in the integral operators. We solve the governing equations exactly and show that the resulting solutions do not represent surface waves.</div></div>","PeriodicalId":14053,"journal":{"name":"International Journal of Engineering Science","volume":"218 ","pages":"Article 104398"},"PeriodicalIF":5.7,"publicationDate":"2025-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145360523","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-21DOI: 10.1016/j.ijengsci.2025.104400
Slawomir Henclik, Waldemar Janicki
Energy transfers and dissipation are important factors within water hammer (WH) runs allowing to reduce pressure amplitudes and other undesired effects like pipeline stresses and vibration. Friction between viscous liquid and pipe walls was a primary identified and accounted effect however, energy can be also dissipated in the structure. A mechanism considered commonly by scientists are internal losses in pipe material. Broader dissipation possibilities appear when the pipeline system is significantly elastic and dynamic fluid structure interaction (FSI) takes place. Among other behaviors, energy can be lost at viscoelastic pipe supports, then. An initial motivation of this study was a detail understanding of a specific result established within WH-FSI experiments conducted at a laboratory pipeline fixed with elastic supports. It was found that reduction of WH pressures in time was faster for a pipeline fixed with less rigid supports. An important remark on this effect is, that elastic elements used in experiments had similar and small damping properties. Explanations of this behavior are proposed and analyzed in this study. One of them is a slip damping mechanism, which can appear at the supports. Logarithmic damping decrement (LDD) is used as a measure of WH amplitudes reduction. An original and novel concept presented is a development and verification of analytical formula for LDD of WH pressure oscillations in a quasi-rigid pipeline, produced by quasi-static hydraulic losses. Additional analyses of measured results, discussion and conclusions are presented in the paper, as well.
{"title":"Water hammer runs in elastically supported pipeline and the impact of system vibrations on pressure amplitudes reduction","authors":"Slawomir Henclik, Waldemar Janicki","doi":"10.1016/j.ijengsci.2025.104400","DOIUrl":"10.1016/j.ijengsci.2025.104400","url":null,"abstract":"<div><div>Energy transfers and dissipation are important factors within water hammer (WH) runs allowing to reduce pressure amplitudes and other undesired effects like pipeline stresses and vibration. Friction between viscous liquid and pipe walls was a primary identified and accounted effect however, energy can be also dissipated in the structure. A mechanism considered commonly by scientists are internal losses in pipe material. Broader dissipation possibilities appear when the pipeline system is significantly elastic and dynamic fluid structure interaction (FSI) takes place. Among other behaviors, energy can be lost at viscoelastic pipe supports, then. An initial motivation of this study was a detail understanding of a specific result established within WH-FSI experiments conducted at a laboratory pipeline fixed with elastic supports. It was found that reduction of WH pressures in time was faster for a pipeline fixed with less rigid supports. An important remark on this effect is, that elastic elements used in experiments had similar and small damping properties. Explanations of this behavior are proposed and analyzed in this study. One of them is a slip damping mechanism, which can appear at the supports. Logarithmic damping decrement (LDD) is used as a measure of WH amplitudes reduction. An original and novel concept presented is a development and verification of analytical formula for LDD of WH pressure oscillations in a quasi-rigid pipeline, produced by quasi-static hydraulic losses. Additional analyses of measured results, discussion and conclusions are presented in the paper, as well.</div></div>","PeriodicalId":14053,"journal":{"name":"International Journal of Engineering Science","volume":"218 ","pages":"Article 104400"},"PeriodicalIF":5.7,"publicationDate":"2025-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145360524","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-21DOI: 10.1016/j.ijengsci.2025.104397
Matteo Franzoi, Davide Bigoni, Andrea Piccolroaz
Two-dimensional architected materials are often realized as periodic grids of elastic beams. Conventional homogenization methods represent these structures as equivalent elastic solids but neglect shear deformation in the constituent beams. This article addresses this limitation by incorporating shear deformability through Timoshenko beam theory, enabling accurate modeling of stubby beams. Moreover, shearable beams with extreme mechanical characteristics can be obtained through the design of appropriate microstructures. Introducing shearable beams into the grid expands the design space, allowing, for instance, the control of the effective Poisson’s ratio beyond the limits achievable with slender beams.
{"title":"Homogenization of architected materials incorporating shearable beams","authors":"Matteo Franzoi, Davide Bigoni, Andrea Piccolroaz","doi":"10.1016/j.ijengsci.2025.104397","DOIUrl":"10.1016/j.ijengsci.2025.104397","url":null,"abstract":"<div><div>Two-dimensional architected materials are often realized as periodic grids of elastic beams. Conventional homogenization methods represent these structures as equivalent elastic solids but neglect shear deformation in the constituent beams. This article addresses this limitation by incorporating shear deformability through Timoshenko beam theory, enabling accurate modeling of stubby beams. Moreover, shearable beams with extreme mechanical characteristics can be obtained through the design of appropriate microstructures. Introducing shearable beams into the grid expands the design space, allowing, for instance, the control of the effective Poisson’s ratio beyond the limits achievable with slender beams.</div></div>","PeriodicalId":14053,"journal":{"name":"International Journal of Engineering Science","volume":"218 ","pages":"Article 104397"},"PeriodicalIF":5.7,"publicationDate":"2025-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145360522","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-17DOI: 10.1016/j.ijengsci.2025.104402
Andrea Genovese, Guido Napolitano Dell’Annunziata, Emanuele Lenzi, Aleksandr Sakhnevych, Francesco Timpone, Flavio Farroni
Maximising tyre performance requires balancing conflicting targets, grip, wear resistance, and rolling efficiency, while accelerating development. In this context, tribological characterisation at compound level supports faster prototyping and reduces reliance on full-scale testing. Although standards for rubber friction testing exist, they are rarely followed in literature, and procedures are often underreported. This work addresses that gap by presenting the complete development of an experimental framework for rubber friction and wear testing, with particular focus on tyre tread compound, from the definition of functional requirements to the design of a novel linear friction tester and the implementation of a robust testing methodology. The Ground Rubber Interface Performance (GRIP) tester was designed for high versatility and cost-effectiveness. A key feature is the open-access architecture, which allows practical surface management and rapid retooling. A custom back-heating system ensures uniform specimen temperature even under varying test conditions. The methodology focuses on critical but overlooked aspects: specimen conditioning, surface rubberisation, and temperature control. Case studies demonstrate the repeatability of results and the system’s sensitivity to key input parameters. Additional tests confirm the platform’s adaptability to non-tyre tribological applications.
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