Pub Date : 2025-07-15DOI: 10.1016/j.eml.2025.102389
Brianna MacNider , Dana M. Dattelbaum , Nicholas Boechler , Carl Cady , Benjamin K. Derby , Saryu Fensin , Kwan-Soo Lee , Jihyeon Kim , Sushan Nakarmi , Nitin Daphalapurkar
Architected materials have shown substantial promise in impact mitigation and protective applications, and there has accordingly been great interest in better characterizing their response at elevated strain rates due to impact. There remains ambiguity regarding the contribution of inertial and material responses to strain rate sensitivity, and, in particular, when these effects begin to gain dominance in the impact response of an architected material. The response of soft polymer architected materials as a function of strain rate, in particular, has been little investigated. We characterize the experimental impact response of four soft polymer architected lattice geometries across varying strain rates in the intermediate strain rate regime (∼103 s−1) using split-Hopkinson pressure bar loading and high speed video characterization of the resulting deformation fields. Our results highlight the interplay of influence between constituent material, lattice geometry, length scale, and strain rate in determining the onset of significant inertia effects.
{"title":"Influence of strain-rate on the response of elastomeric architected materials","authors":"Brianna MacNider , Dana M. Dattelbaum , Nicholas Boechler , Carl Cady , Benjamin K. Derby , Saryu Fensin , Kwan-Soo Lee , Jihyeon Kim , Sushan Nakarmi , Nitin Daphalapurkar","doi":"10.1016/j.eml.2025.102389","DOIUrl":"10.1016/j.eml.2025.102389","url":null,"abstract":"<div><div>Architected materials have shown substantial promise in impact mitigation and protective applications, and there has accordingly been great interest in better characterizing their response at elevated strain rates due to impact. There remains ambiguity regarding the contribution of inertial and material responses to strain rate sensitivity, and, in particular, when these effects begin to gain dominance in the impact response of an architected material. The response of soft polymer architected materials as a function of strain rate, in particular, has been little investigated. We characterize the experimental impact response of four soft polymer architected lattice geometries across varying strain rates in the intermediate strain rate regime (∼10<sup>3</sup> s<sup>−1</sup>) using split-Hopkinson pressure bar loading and high speed video characterization of the resulting deformation fields. Our results highlight the interplay of influence between constituent material, lattice geometry, length scale, and strain rate in determining the onset of significant inertia effects.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"79 ","pages":"Article 102389"},"PeriodicalIF":4.3,"publicationDate":"2025-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144670476","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}
Pub Date : 2025-07-10DOI: 10.1016/j.eml.2025.102384
Ziyong Li , Yanwen Jia , Fang Su , Juzheng Chen , Xiewen Wen , Wenjun Liang , Hao Wu , Yang Lu
Micro-electro-mechanical systems (MEMS)-based devices offers a premium solution for versatile in situ micro-/nano- mechanical characterizations of low-dimensional materials, however, they are primarily manufactured using costly top-down silicon photolithography microfabrication processes. Previously, we demonstrated that high-resolution bottom-up 3D printing technologies can be used for printing such micro-mechanical device (MMD), but those photopolymer-based devices are of low-modulus and less stable for long-term use. Here, based on our recently developed high-resolution glass 3D printing technique, we show that silica glass MMD with high definition and performance. The versatility of high-resolution additive manufacturing, combined with the long-term mechanical stability as well as exceptional mechanical properties of high-performance glass, enables the fabrication of MMDs with more desirable characteristics. This facilitates the in-situ micro-/nano- mechanical characterizations on novel materials. The tensile behaviors of microfibers and nanofilms, as demonstrated by our developed MMDs, showcase the potential for a groundbreaking approach to in situ micro-/nano- mechanical testing through the integration of 3D printing, high-performance glass, and MEMS technologies.
{"title":"3D-printed silica glass micro-mechanical device (MMD) for in situ mechanical testing","authors":"Ziyong Li , Yanwen Jia , Fang Su , Juzheng Chen , Xiewen Wen , Wenjun Liang , Hao Wu , Yang Lu","doi":"10.1016/j.eml.2025.102384","DOIUrl":"10.1016/j.eml.2025.102384","url":null,"abstract":"<div><div>Micro-electro-mechanical systems (MEMS)-based devices offers a premium solution for versatile <em>in situ</em> micro-/nano- mechanical characterizations of low-dimensional materials, however, they are primarily manufactured using costly top-down silicon photolithography microfabrication processes. Previously, we demonstrated that high-resolution bottom-up 3D printing technologies can be used for printing such micro-mechanical device (MMD), but those photopolymer-based devices are of low-modulus and less stable for long-term use. Here, based on our recently developed high-resolution glass 3D printing technique, we show that silica glass MMD with high definition and performance. The versatility of high-resolution additive manufacturing, combined with the long-term mechanical stability as well as exceptional mechanical properties of high-performance glass, enables the fabrication of MMDs with more desirable characteristics. This facilitates the in-situ micro-/nano- mechanical characterizations on novel materials. The tensile behaviors of microfibers and nanofilms, as demonstrated by our developed MMDs, showcase the potential for a groundbreaking approach to <em>in situ</em> micro-/nano- mechanical testing through the integration of 3D printing, high-performance glass, and MEMS technologies.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"78 ","pages":"Article 102384"},"PeriodicalIF":4.3,"publicationDate":"2025-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144604666","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}
Pub Date : 2025-07-07DOI: 10.1016/j.eml.2025.102380
Xi Qie, Jianping Lin
Numerous studies have investigated Lüders band and transformation stress plateau in NiTi. However, localized plastic deformation (LPD) of martensite and the stress drop before the second stress plateau remain poorly understood. In this study, drawing an analogy to Lüders band propagation, we observed LPD band nucleation propagation in a microstructure with 253 nm grain size by in-situ Digital Image Correlation (DIC). Based on displacement conservation, we propose a mechanical criterion for inelastic loading in NiTi. This criterion accurately predicts the stress drop associated with LPD band nucleation and movement, providing a theoretical foundation. Furthermore, we systematically explain, for the first time, the abnormal strain softening effect responsible for the second stress plateau during martensitic plastic deformation. By offering new insights into martensitic transformation and LPD mechanisms, this research advances the understanding of dual stress plateaus and LPD in NiTi.
{"title":"A novel mechanical criterion and interpretation for dual stress plateau phenomenon in NiTi alloy under tension","authors":"Xi Qie, Jianping Lin","doi":"10.1016/j.eml.2025.102380","DOIUrl":"10.1016/j.eml.2025.102380","url":null,"abstract":"<div><div>Numerous studies have investigated Lüders band and transformation stress plateau in NiTi. However, localized plastic deformation (LPD) of martensite and the stress drop before the second stress plateau remain poorly understood. In this study, drawing an analogy to Lüders band propagation, we observed LPD band nucleation propagation in a microstructure with 253 nm grain size by in-situ Digital Image Correlation (DIC). Based on displacement conservation, we propose a mechanical criterion for inelastic loading in NiTi. This criterion accurately predicts the stress drop associated with LPD band nucleation and movement, providing a theoretical foundation. Furthermore, we systematically explain, for the first time, the abnormal strain softening effect responsible for the second stress plateau during martensitic plastic deformation. By offering new insights into martensitic transformation and LPD mechanisms, this research advances the understanding of dual stress plateaus and LPD in NiTi.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"78 ","pages":"Article 102380"},"PeriodicalIF":4.3,"publicationDate":"2025-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144604665","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}
Pub Date : 2025-07-04DOI: 10.1016/j.eml.2025.102377
Po-Ting Lin , Congyuan Zhang , Yichun Tang , Hanwen Fan , Kaleb Barker , Nathan Harward , Ecem Kilic , Zachary Rickmeyer , Gregory S. Lewis , April D. Armstrong , Jing Du , Yuxiao Zhou
Loosening of the shoulder joint (glenohumeral joint) implant is a leading cause of failure in total shoulder replacement surgery, primarily due to mechanical strain concentration in the bone. This study combines in situ mechanical testing with micro-X-ray computed tomography (micro-CT) to apply physiologically realistic loads on non-arthritic and arthritic glenoid bones, the socket portion of the shoulder joint, before and after implant placement, and uses digital volume correlation (DVC) to analyze 3D deformation and strain distributions within the glenoid bones. The results show that degenerative changes in bone quality and structure associated with different arthritis subtypes redistribute strain under anterior and posterior eccentric loading. Strain distributions were compared across arthritis subtypes before and after implant placement, with results indicating that implant placement often helps alleviate strain concentrations. Additionally, the percentage of bone volume experiencing strain beyond the physiological strain range typically encountered during daily activities was assessed. While the proportion of bone exceeding this strain threshold was comparable between non-arthritic and arthritic glenoid bones post-implantation, strain magnitude was notably higher in arthritic specimens, potentially increasing the risk of implant loosening. These findings provide insights for optimizing preoperative planning and implant design tailored to patient-specific bone characteristics, potentially enhancing implant longevity and reducing the risk of post-surgical loosening in patients with glenohumeral arthritis.
{"title":"Full-field strain distribution in non-arthritic and arthritic glenoid bones before and after implant placement measured by digital volume correlation method","authors":"Po-Ting Lin , Congyuan Zhang , Yichun Tang , Hanwen Fan , Kaleb Barker , Nathan Harward , Ecem Kilic , Zachary Rickmeyer , Gregory S. Lewis , April D. Armstrong , Jing Du , Yuxiao Zhou","doi":"10.1016/j.eml.2025.102377","DOIUrl":"10.1016/j.eml.2025.102377","url":null,"abstract":"<div><div>Loosening of the shoulder joint (glenohumeral joint) implant is a leading cause of failure in total shoulder replacement surgery, primarily due to mechanical strain concentration in the bone. This study combines <em>in situ</em> mechanical testing with micro-X-ray computed tomography (micro-CT) to apply physiologically realistic loads on non-arthritic and arthritic glenoid bones, the socket portion of the shoulder joint, before and after implant placement, and uses digital volume correlation (DVC) to analyze 3D deformation and strain distributions within the glenoid bones. The results show that degenerative changes in bone quality and structure associated with different arthritis subtypes redistribute strain under anterior and posterior eccentric loading. Strain distributions were compared across arthritis subtypes before and after implant placement, with results indicating that implant placement often helps alleviate strain concentrations. Additionally, the percentage of bone volume experiencing strain beyond the physiological strain range typically encountered during daily activities was assessed. While the proportion of bone exceeding this strain threshold was comparable between non-arthritic and arthritic glenoid bones post-implantation, strain magnitude was notably higher in arthritic specimens, potentially increasing the risk of implant loosening. These findings provide insights for optimizing preoperative planning and implant design tailored to patient-specific bone characteristics, potentially enhancing implant longevity and reducing the risk of post-surgical loosening in patients with glenohumeral arthritis.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"78 ","pages":"Article 102377"},"PeriodicalIF":4.3,"publicationDate":"2025-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144580475","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}
Pub Date : 2025-06-25DOI: 10.1016/j.eml.2025.102376
Zhonggang Wang , Xinying Lu , Yiming Zhao , Kexin Zeng , Ziping Lei , Tiecheng Wang , Zhendong Li , Zichao Guo
While local-resonance acoustic metamaterials with parallel arrangements provide a feasible means for subwavelength control of sound waves, their practical applications are severely limited by the presence of multiple insulation valleys between the resonance effects. A new design framework for gradient-channel acoustic metamaterials is introduced by harnessing the nonlocal coupling effect. This mechanism strengthens the interaction between adjacent unit cells, with nonlocal regions acting as secondary acoustic sources. Consequently, phase cancellation is extended throughout the metamaterial, eliminating significant sound insulation valleys. Our theoretical, numerical, and experimental investigations reveal that the proposed nonlocal metamaterial enhances sound insulation by 15.8 % over the 400–2500 Hz range compared to conventional parallel metamaterials at the deep-subwavelength scale. Furthermore, a bilayer metamaterial, combining local and nonlocal designs, achieves an average sound transmission loss of 32.8 dB. By exploiting the nonlocal effect, this work significantly expands the design space for multi-channel acoustic metamaterials, enabling efficient manipulation of low-frequency waves over a wide bandwidth. It provides a novel route for developing ultrathin, high-efficiency sound insulators.
{"title":"Harnessing nonlocal coupling effect to enhance broadband sound insulation in gradient acoustic metamaterial","authors":"Zhonggang Wang , Xinying Lu , Yiming Zhao , Kexin Zeng , Ziping Lei , Tiecheng Wang , Zhendong Li , Zichao Guo","doi":"10.1016/j.eml.2025.102376","DOIUrl":"10.1016/j.eml.2025.102376","url":null,"abstract":"<div><div>While local-resonance acoustic metamaterials with parallel arrangements provide a feasible means for subwavelength control of sound waves, their practical applications are severely limited by the presence of multiple insulation valleys between the resonance effects. A new design framework for gradient-channel acoustic metamaterials is introduced by harnessing the nonlocal coupling effect. This mechanism strengthens the interaction between adjacent unit cells, with nonlocal regions acting as secondary acoustic sources. Consequently, phase cancellation is extended throughout the metamaterial, eliminating significant sound insulation valleys. Our theoretical, numerical, and experimental investigations reveal that the proposed nonlocal metamaterial enhances sound insulation by 15.8 % over the 400–2500 Hz range compared to conventional parallel metamaterials at the deep-subwavelength scale. Furthermore, a bilayer metamaterial, combining local and nonlocal designs, achieves an average sound transmission loss of 32.8 dB. By exploiting the nonlocal effect, this work significantly expands the design space for multi-channel acoustic metamaterials, enabling efficient manipulation of low-frequency waves over a wide bandwidth. It provides a novel route for developing ultrathin, high-efficiency sound insulators.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"78 ","pages":"Article 102376"},"PeriodicalIF":4.3,"publicationDate":"2025-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144513974","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}
Pub Date : 2025-06-23DOI: 10.1016/j.eml.2025.102368
Nusrat Jahan Salim, Ignacio Arretche, Kathryn H. Matlack
Soft magnetoactive elastomers (sMAEs) are promising multifunctional composites obtained by embedding soft-magnetic particles into an elastomer matrix. Under external magnetic fields, these composites exhibit tunability in mechanical and rheological properties, including stiffness modulation and controllable deformation. Despite growing interest in their magneto-mechanical capabilities, the fracture behavior of sMAEs under magnetic fields remains entirely unexplored. Here, we present the first comprehensive experimental characterization of the fracture toughness and underlying fracture mechanisms in sMAEs subjected to magnetic fields. The study includes different volume fractions of particles, with particles arranged both randomly and aligned, parallel and perpendicular to the loading direction. Experimental results show that in the presence of a magnetic field, fracture toughness increases by 42% for anisotropic sMAEs and 23% for isotropic sMAEs, compared to their unmagnetized states. With the aid of the load-stretch curves, spatial distribution of strain from Digital Image Correlation (DIC), and optical microscopy images of the test specimens, we identify two key mechanisms driving the observed toughening: bulk magneto-mechanical induced stiffening and/or local magneto-mechanical coupling near the crack tip that delays catastrophic failure. This work bridges a critical knowledge gap and expands the design space for durable and adaptive multifunctional magneto-responsive composites.
{"title":"Magnetic field induced toughening mechanisms in isotropic and anisotropic soft magnetoactive elastomers","authors":"Nusrat Jahan Salim, Ignacio Arretche, Kathryn H. Matlack","doi":"10.1016/j.eml.2025.102368","DOIUrl":"10.1016/j.eml.2025.102368","url":null,"abstract":"<div><div>Soft magnetoactive elastomers (sMAEs) are promising multifunctional composites obtained by embedding soft-magnetic particles into an elastomer matrix. Under external magnetic fields, these composites exhibit tunability in mechanical and rheological properties, including stiffness modulation and controllable deformation. Despite growing interest in their magneto-mechanical capabilities, the fracture behavior of sMAEs under magnetic fields remains entirely unexplored. Here, we present the first comprehensive experimental characterization of the fracture toughness and underlying fracture mechanisms in sMAEs subjected to magnetic fields. The study includes different volume fractions of particles, with particles arranged both randomly and aligned, parallel and perpendicular to the loading direction. Experimental results show that in the presence of a magnetic field, fracture toughness increases by 42% for anisotropic sMAEs and 23% for isotropic sMAEs, compared to their unmagnetized states. With the aid of the load-stretch curves, spatial distribution of strain from Digital Image Correlation (DIC), and optical microscopy images of the test specimens, we identify two key mechanisms driving the observed toughening: bulk magneto-mechanical induced stiffening and/or local magneto-mechanical coupling near the crack tip that delays catastrophic failure. This work bridges a critical knowledge gap and expands the design space for durable and adaptive multifunctional magneto-responsive composites.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"78 ","pages":"Article 102368"},"PeriodicalIF":4.3,"publicationDate":"2025-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144480749","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}
Pub Date : 2025-06-23DOI: 10.1016/j.eml.2025.102369
Taiki Goto , Shunsuke Nomura , Tomohiko G. Sano
Knots across various length scales, from micro to macro-scales, such as polymers, DNA, shoelaces, and surgery, serving their unique mechanical properties. The shapes of ideal knots have been extensively studied in the context of knot theory, while those of physical knots have only been recently discussed in the literature. The complex interplay of elasticity and geometry, such as bending, twisting, and contact, needs to be disentangled to predict their deformation. Still, the unified understanding of the deformation of physical knots is insufficient. Here, we focus on the trefoil knot, a closed knot with a nontrivial topology, and study the relationship between the shapes of the trefoil knot and applied physical twists, combining experiments and simulations. As we twist the elastomeric rod, the knot becomes either tightened or loosened, preserving the original three-fold symmetry, and then buckles and exhibits symmetry breaking at critical angles. The curvature profiles computed through the X-ray tomography (CT) analysis also exhibit similar symmetry breaking. The transition would be triggered by the mechanical instability, where the imposed twist energy is converted into the bending energy. The phase transition observed here is analogous to the classical buckling phenomena of elastic rings known as the Michell instability. We find that the twist buckling instability of the trefoil knot results from the interplay of bending, twisting, and contact properties of the rod. In other words, the buckling of the knot is predictable based on the elasticity and geometry of rods, which would be useful in avoiding or even utilizing their buckling in practical engineering applications such as surgery and the shipping industry.
{"title":"Twist deformation of physical trefoil knots","authors":"Taiki Goto , Shunsuke Nomura , Tomohiko G. Sano","doi":"10.1016/j.eml.2025.102369","DOIUrl":"10.1016/j.eml.2025.102369","url":null,"abstract":"<div><div>Knots across various length scales, from micro to macro-scales, such as polymers, DNA, shoelaces, and surgery, serving their unique mechanical properties. The shapes of ideal knots have been extensively studied in the context of knot theory, while those of physical knots have only been recently discussed in the literature. The complex interplay of elasticity and geometry, such as bending, twisting, and contact, needs to be disentangled to predict their deformation. Still, the unified understanding of the deformation of physical knots is insufficient. Here, we focus on the trefoil knot, a closed knot with a nontrivial topology, and study the relationship between the shapes of the trefoil knot and applied physical twists, combining experiments and simulations. As we twist the elastomeric rod, the knot becomes either tightened or loosened, preserving the original three-fold symmetry, and then buckles and exhibits symmetry breaking at critical angles. The curvature profiles computed through the X-ray tomography (<span><math><mi>μ</mi></math></span>CT) analysis also exhibit similar symmetry breaking. The transition would be triggered by the mechanical instability, where the imposed twist energy is converted into the bending energy. The phase transition observed here is analogous to the classical buckling phenomena of elastic rings known as the Michell instability. We find that the twist buckling instability of the trefoil knot results from the interplay of bending, twisting, and contact properties of the rod. In other words, the buckling of the knot is predictable based on the elasticity and geometry of rods, which would be useful in avoiding or even utilizing their buckling in practical engineering applications such as surgery and the shipping industry.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"78 ","pages":"Article 102369"},"PeriodicalIF":4.3,"publicationDate":"2025-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144489504","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}
Hydrogels are often stretchable and soft. Therefore, when two hydrogels are bonded by an adhesive, the adhesive layer should be stretchable so as not to degrade adhesion during stretching, and should also be soft so as not to affect the mechanical properties (e.g., stress-stretch relationship, modulus, and stretch at rupture) of the hydrogel adherends. Topological adhesion has been one of the state-of-the-art adhesion methods for bonding hydrogels, and stretchable topological adhesion (STA) has been well documented in the literature. However, topological hydrogel adhesion that is both stretchable and soft has not been achieved yet. Here, we demonstrate a soft stretchable topological adhesion (SSTA) strategy using long and flexible stitching polymers that can form topological entanglements with the adherend network as the adhesive. Experimental results indicate that the topological adhesion produced by the SSTA strategy is stretchable, i.e., the adhesion energy is insensitive to applied stretches, and soft, i.e., the application of the adhesive does not alter the stress-stretch relationship, modulus, and stretch at rupture of the hydrogel adherends, which is not possible with existing STA methods for hydrogels. A resistive strain sensor and a soft gripper integrated by the SSTA method are demonstrated.
{"title":"Soft stretchable topological adhesion of hydrogels","authors":"Daochen Yin, Jie Ma, Zihang Shen, Zhi Sheng, Yuren Yin, Zheng Jia","doi":"10.1016/j.eml.2025.102373","DOIUrl":"10.1016/j.eml.2025.102373","url":null,"abstract":"<div><div>Hydrogels are often stretchable and soft. Therefore, when two hydrogels are bonded by an adhesive, the adhesive layer should be stretchable so as not to degrade adhesion during stretching, and should also be soft so as not to affect the mechanical properties (e.g., stress-stretch relationship, modulus, and stretch at rupture) of the hydrogel adherends. Topological adhesion has been one of the state-of-the-art adhesion methods for bonding hydrogels, and stretchable topological adhesion (STA) has been well documented in the literature. However, topological hydrogel adhesion that is both stretchable and soft has not been achieved yet. Here, we demonstrate a soft stretchable topological adhesion (SSTA) strategy using long and flexible stitching polymers that can form topological entanglements with the adherend network as the adhesive. Experimental results indicate that the topological adhesion produced by the SSTA strategy is stretchable, i.e., the adhesion energy is insensitive to applied stretches, and soft, i.e., the application of the adhesive does not alter the stress-stretch relationship, modulus, and stretch at rupture of the hydrogel adherends, which is not possible with existing STA methods for hydrogels. A resistive strain sensor and a soft gripper integrated by the SSTA method are demonstrated.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"78 ","pages":"Article 102373"},"PeriodicalIF":4.3,"publicationDate":"2025-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144366173","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}
Pub Date : 2025-06-20DOI: 10.1016/j.eml.2025.102374
Haowei Ruan , Ping Zhang , Canhui Yang
Strong adhesion and low hysteresis are essential for the applications of soft polymeric adhesives, but unifying them is challenging due to their contradictory relations with network structures. In this study, we investigate the design principles of hyperelastic and adhesive heterogeneous polymer networks under shear conditions. The heterogeneous polymer networks, composed of two adhesive layers sandwiching a hyperelastic bulk, which are in series upon shear, are generally adhesive but hysteretic. Our theoretical analysis shows that a large thickness ratio and a small shear modulus ratio between the hyperelastic bulk and the adhesive surface are crucial for minimizing hysteresis. We verify the principles by synthesizing heterogeneous polymer networks consisting of a layer of PBA sandwiched between two layers of P(BA-co-IBA-co-AA) and examining their hysteresis via cyclic shear tests. The theoretical predictions agree well with experimental results. We further show that the design criteria for low hysteresis also apply to achieving high creep recovery. This work provides mechanistic insights into the rational design and synthesis of soft polymeric adhesives for applications in flexible electronics, soft robotics, and beyond, where shear loads prevail, and strong adhesion and low hysteresis are mission-critical.
{"title":"Designing hyperelastic and adhesive heterogeneous polymer networks under shear conditions","authors":"Haowei Ruan , Ping Zhang , Canhui Yang","doi":"10.1016/j.eml.2025.102374","DOIUrl":"10.1016/j.eml.2025.102374","url":null,"abstract":"<div><div>Strong adhesion and low hysteresis are essential for the applications of soft polymeric adhesives, but unifying them is challenging due to their contradictory relations with network structures. In this study, we investigate the design principles of hyperelastic and adhesive heterogeneous polymer networks under shear conditions. The heterogeneous polymer networks, composed of two adhesive layers sandwiching a hyperelastic bulk, which are in series upon shear, are generally adhesive but hysteretic. Our theoretical analysis shows that a large thickness ratio and a small shear modulus ratio between the hyperelastic bulk and the adhesive surface are crucial for minimizing hysteresis. We verify the principles by synthesizing heterogeneous polymer networks consisting of a layer of PBA sandwiched between two layers of P(BA-<em>co</em>-IBA-<em>co</em>-AA) and examining their hysteresis via cyclic shear tests. The theoretical predictions agree well with experimental results. We further show that the design criteria for low hysteresis also apply to achieving high creep recovery. This work provides mechanistic insights into the rational design and synthesis of soft polymeric adhesives for applications in flexible electronics, soft robotics, and beyond, where shear loads prevail, and strong adhesion and low hysteresis are mission-critical.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"78 ","pages":"Article 102374"},"PeriodicalIF":4.3,"publicationDate":"2025-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144366174","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}
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