Pub Date : 2024-08-27DOI: 10.1088/1361-665x/ad6f82
Yangkun Zhang, Mengze Lao, Yang Yang
A new working principle of inchworm actuator, which converts vibrations of a single piezo actuator into unidirectional step movement of a mover via a ratchet mechanism, was proposed. The proposed working principle has the following priorities: (1) it requires only one piezoelectric actuator which greatly simplifies its driving signals and driving circuits; (2) it can achieve a large driving speed with little compromise of a large force output while maintaining a high positioning precision of piezoelectric actuator and a theoretically unlimited motion range, although it can only achieve unidirectional movement with unidirectional self-locking capability; (3) it could be open-loop controlled with no accumulated step errors. The proposed actuator was designed with compliant mechanism and an analytical model of the design was developed, validated by finite element simulations carried out in Commercial Software ANSYS and used to guide the selection of design parameters. A prototype was fabricated and tested. Experiments show that the proposed actuator achieved a speed larger than 12 mm s−1, a driving load larger than 60 N in the moving direction, a reliable open-loop controllability with no step accumulated errors even under driving load variations of 60 N, and a working range larger than 1 mm with a high positioning precision around 320 nm under closed-loop control, which validated the superiorities of the proposed actuator.
提出了一种新的尺蠖致动器工作原理，通过棘轮机构将单个压电致动器的振动转换为移动器的单向步进运动。所提出的工作原理有以下几个重点：（1）只需一个压电致动器，大大简化了驱动信号和驱动电路；（2）虽然只能实现单向运动，但可以在保持压电致动器高定位精度和理论上无限运动范围的前提下，以较小的折衷大力输出实现较大的驱动速度，并具有单向自锁能力；（3）可实现开环控制，无累积步进误差。拟议的致动器采用顺从式机构设计，并建立了设计分析模型，通过商用软件 ANSYS 进行有限元模拟验证，并用于指导设计参数的选择。原型已制作完成并进行了测试。实验表明，所提出的致动器的速度大于 12 mm s-1，在移动方向上的驱动负载大于 60 N，具有可靠的开环可控性，即使在驱动负载变化为 60 N 的情况下也不会出现阶跃累积误差，而且在闭环控制下，工作范围大于 1 mm，定位精度高达 320 nm 左右，这些都验证了所提出的致动器的优越性。
{"title":"A novel linear piezoelectric inchworm actuator based on a ratchet mechanism","authors":"Yangkun Zhang, Mengze Lao, Yang Yang","doi":"10.1088/1361-665x/ad6f82","DOIUrl":"https://doi.org/10.1088/1361-665x/ad6f82","url":null,"abstract":"A new working principle of inchworm actuator, which converts vibrations of a single piezo actuator into unidirectional step movement of a mover via a ratchet mechanism, was proposed. The proposed working principle has the following priorities: (1) it requires only one piezoelectric actuator which greatly simplifies its driving signals and driving circuits; (2) it can achieve a large driving speed with little compromise of a large force output while maintaining a high positioning precision of piezoelectric actuator and a theoretically unlimited motion range, although it can only achieve unidirectional movement with unidirectional self-locking capability; (3) it could be open-loop controlled with no accumulated step errors. The proposed actuator was designed with compliant mechanism and an analytical model of the design was developed, validated by finite element simulations carried out in Commercial Software ANSYS and used to guide the selection of design parameters. A prototype was fabricated and tested. Experiments show that the proposed actuator achieved a speed larger than 12 mm s<sup>−1</sup>, a driving load larger than 60 N in the moving direction, a reliable open-loop controllability with no step accumulated errors even under driving load variations of 60 N, and a working range larger than 1 mm with a high positioning precision around 320 nm under closed-loop control, which validated the superiorities of the proposed actuator.","PeriodicalId":21656,"journal":{"name":"Smart Materials and Structures","volume":"81 1","pages":""},"PeriodicalIF":4.1,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142178684","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-27DOI: 10.1088/1361-665x/ad6f83
Xiaofeng Yan, Xianggang Li, Qianmei Yin, Jingjing Tong, Tao Xie
A rheological measurement system was constructed to investigate the rheological behavior of magnetic fluids under a wide range of shear rates, and its feasibility was verified. The system is capable of measuring a shear rate range spanning five orders of magnitude, with a maximum shear rate of 106 s−1. It was utilized to study the time required for aqueous magnetic fluids in a magnetic field to reach a steady state, taking into account the coupling effect of the flow field and magnetic field. Additionally, the time needed for the magnetic fluids to return to their initial state after demagnetization was also measured. Based on these measurements, the rheological behavior of magnetic fluids with varying concentrations and magnetic field directions was studied. Results indicate that the residence time of the magnetic fluids in the magnetic field and the de-magnetization time have almost no effect on their viscosity. When the magnetic field direction is perpendicular to the flow direction, regardless of concentration, aqueous magnetic fluids exhibit shear thinning behavior; when it is parallel to the flow direction, high-concentration aqueous magnetic fluids show shear thickening, while low-concentration ones behave as Newtonian fluids. In this study’s shear rate range, no Newtonian regions were found in either high- or low-shear rate regions.
{"title":"The rheological behavior of aqueous magnetic fluids over a wide range of shear rates","authors":"Xiaofeng Yan, Xianggang Li, Qianmei Yin, Jingjing Tong, Tao Xie","doi":"10.1088/1361-665x/ad6f83","DOIUrl":"https://doi.org/10.1088/1361-665x/ad6f83","url":null,"abstract":"A rheological measurement system was constructed to investigate the rheological behavior of magnetic fluids under a wide range of shear rates, and its feasibility was verified. The system is capable of measuring a shear rate range spanning five orders of magnitude, with a maximum shear rate of 10<sup>6</sup> s<sup>−1</sup>. It was utilized to study the time required for aqueous magnetic fluids in a magnetic field to reach a steady state, taking into account the coupling effect of the flow field and magnetic field. Additionally, the time needed for the magnetic fluids to return to their initial state after demagnetization was also measured. Based on these measurements, the rheological behavior of magnetic fluids with varying concentrations and magnetic field directions was studied. Results indicate that the residence time of the magnetic fluids in the magnetic field and the de-magnetization time have almost no effect on their viscosity. When the magnetic field direction is perpendicular to the flow direction, regardless of concentration, aqueous magnetic fluids exhibit shear thinning behavior; when it is parallel to the flow direction, high-concentration aqueous magnetic fluids show shear thickening, while low-concentration ones behave as Newtonian fluids. In this study’s shear rate range, no Newtonian regions were found in either high- or low-shear rate regions.","PeriodicalId":21656,"journal":{"name":"Smart Materials and Structures","volume":"41 1","pages":""},"PeriodicalIF":4.1,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142223639","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Flexible tactile sensors are an important branch of wearable devices and have received extensive attention in areas such as human–computer interaction and health detection. However, some existing flexible wearable devices have the limitation of single detection quantity, so it is particularly important to study a multi-mode flexible tactile sensor. We designed a dual-mode tactile sensor with high sensitivity and wide measurement range. The sensor consists of a magnetic film in the top layer, a silicone elastomer in the middle layer, and a tunneling magnetoresistive element in the bottom layer. The experimental results show that the haptic sensor is capable of measuring static forces in the range of 0.05–18 N, and the sensitivity of the sensor to static forces increases and then decreases as the applied force increases. The maximum sensitivity was 396.4 mV N−1 in the range of 9–10 N. The tactile sensor was able to measure bending angle in the range of 1–60°. The bending angle sensitivity decreases as the applied bending angle increases, with a maximum sensitivity of 308.7 mV per 5° in the 0–5° range. The sensor has good dynamic performance, and after 1000 cyclic loading tests, the output voltage did not show any significant decrease, and the sensor response time and recovery time were 44 ms and 46 ms, respectively. This study lays a foundation for further research and development of various wearable devices and electronic skins.
{"title":"Dual-mode flexible sensor based on magnetic film for wearable smart finger sleeve","authors":"Guoheng Lin, Ling Weng, Hui Zhang, Zhuolin Li, Boyang Hu, Kai Meng, Shengwang Jiang","doi":"10.1088/1361-665x/ad6ecf","DOIUrl":"https://doi.org/10.1088/1361-665x/ad6ecf","url":null,"abstract":"Flexible tactile sensors are an important branch of wearable devices and have received extensive attention in areas such as human–computer interaction and health detection. However, some existing flexible wearable devices have the limitation of single detection quantity, so it is particularly important to study a multi-mode flexible tactile sensor. We designed a dual-mode tactile sensor with high sensitivity and wide measurement range. The sensor consists of a magnetic film in the top layer, a silicone elastomer in the middle layer, and a tunneling magnetoresistive element in the bottom layer. The experimental results show that the haptic sensor is capable of measuring static forces in the range of 0.05–18 N, and the sensitivity of the sensor to static forces increases and then decreases as the applied force increases. The maximum sensitivity was 396.4 mV N<sup>−1</sup> in the range of 9–10 N. The tactile sensor was able to measure bending angle in the range of 1–60°. The bending angle sensitivity decreases as the applied bending angle increases, with a maximum sensitivity of 308.7 mV per 5° in the 0–5° range. The sensor has good dynamic performance, and after 1000 cyclic loading tests, the output voltage did not show any significant decrease, and the sensor response time and recovery time were 44 ms and 46 ms, respectively. This study lays a foundation for further research and development of various wearable devices and electronic skins.","PeriodicalId":21656,"journal":{"name":"Smart Materials and Structures","volume":"113 1","pages":""},"PeriodicalIF":4.1,"publicationDate":"2024-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142178686","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-22DOI: 10.1088/1361-665x/ad6ed1
Yang Yang, Peng Wang, Jia Liu, Yili Fu, Yang Shen
In this article, a tunable stiffness soft gripper based on Kirigami structure and shape memory polymer (SMP) is proposed. The Kirigami gripper uses SMP as variable stiffness element and employs Nichrome heating wires laid inside the gripper as heating element. Due to the segmented layout of the heating wires, the gripper possesses segmented stiffness modulation capability. As a result, programmable deformation trajectories are achieved, enabling multi-mode grasping functionality by adjusting its bending shape to accommodate different object contours. Using the thermally activated supercoiled polymer artificial muscle as the actuator, the gripper can achieve a silent and pumpless actuation and whole robotic system can be compact. The gripper mainly offers three different grasping modes—pinching, wrapping and hooking, to meet the requirements of complex tasks. Experimental results show that the Kirigami gripper can achieve a 13 times stiffness variation within 16 s, and each Kirigami gripper with different heating patterns exhibits different trajectories during the deformation process, capable of adapting and locking its shape to objects with different contours during grasping.
{"title":"Tunable stiffness Kirigami gripper based on shape memory polymer and supercoiled polymer artificial muscle for multi-mode grasping","authors":"Yang Yang, Peng Wang, Jia Liu, Yili Fu, Yang Shen","doi":"10.1088/1361-665x/ad6ed1","DOIUrl":"https://doi.org/10.1088/1361-665x/ad6ed1","url":null,"abstract":"In this article, a tunable stiffness soft gripper based on Kirigami structure and shape memory polymer (SMP) is proposed. The Kirigami gripper uses SMP as variable stiffness element and employs Nichrome heating wires laid inside the gripper as heating element. Due to the segmented layout of the heating wires, the gripper possesses segmented stiffness modulation capability. As a result, programmable deformation trajectories are achieved, enabling multi-mode grasping functionality by adjusting its bending shape to accommodate different object contours. Using the thermally activated supercoiled polymer artificial muscle as the actuator, the gripper can achieve a silent and pumpless actuation and whole robotic system can be compact. The gripper mainly offers three different grasping modes—pinching, wrapping and hooking, to meet the requirements of complex tasks. Experimental results show that the Kirigami gripper can achieve a 13 times stiffness variation within 16 s, and each Kirigami gripper with different heating patterns exhibits different trajectories during the deformation process, capable of adapting and locking its shape to objects with different contours during grasping.","PeriodicalId":21656,"journal":{"name":"Smart Materials and Structures","volume":"11 1","pages":""},"PeriodicalIF":4.1,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142178699","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-14DOI: 10.1088/1361-665x/ad6cbb
Weimian Zhou, Chanchan Xu, Guisong Chen, Xiaojie Wang
Suction cups has been widely utilized to grasp objects, but they typically encounter challenges with sealing failure and non-adjustable adhesion force. In this study, a bioinspired suction cup integrated with an shape memory alloy actuated module was proposed to solve these problems. The actuating performance under different input current was firstly investigated to ensure the effectiveness of the module. Then, inspired by the surface structures of the tree frog’s toe pad, the synthetic bioinspired suction cups with hexagonal microstructures at the rims were designed. The regular cup with soft and smooth rim was also fabricated for comparison study. Furthermore, the adhesion performance and surface adaptability of different two cups were studied in both dry and water conditions on substrates with various roughness levels. The results indicated that the proposed active bioinspired suction cup exhibited higher pull-off strength and better sealing on less rough substrates. The proposed bioinspired suction cup possessed the advantages of compactness and lightweight, thus demonstrating potential for integration into arrayed suction grippers.
{"title":"A soft bioinspired suction cup with tunable adhesion force using shape memory alloy","authors":"Weimian Zhou, Chanchan Xu, Guisong Chen, Xiaojie Wang","doi":"10.1088/1361-665x/ad6cbb","DOIUrl":"https://doi.org/10.1088/1361-665x/ad6cbb","url":null,"abstract":"Suction cups has been widely utilized to grasp objects, but they typically encounter challenges with sealing failure and non-adjustable adhesion force. In this study, a bioinspired suction cup integrated with an shape memory alloy actuated module was proposed to solve these problems. The actuating performance under different input current was firstly investigated to ensure the effectiveness of the module. Then, inspired by the surface structures of the tree frog’s toe pad, the synthetic bioinspired suction cups with hexagonal microstructures at the rims were designed. The regular cup with soft and smooth rim was also fabricated for comparison study. Furthermore, the adhesion performance and surface adaptability of different two cups were studied in both dry and water conditions on substrates with various roughness levels. The results indicated that the proposed active bioinspired suction cup exhibited higher pull-off strength and better sealing on less rough substrates. The proposed bioinspired suction cup possessed the advantages of compactness and lightweight, thus demonstrating potential for integration into arrayed suction grippers.","PeriodicalId":21656,"journal":{"name":"Smart Materials and Structures","volume":"32 1","pages":""},"PeriodicalIF":4.1,"publicationDate":"2024-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142178702","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-14DOI: 10.1088/1361-665x/ad69ea
J P Sena, A M G de Lima, N Bouhaddi, N Kacem
With the growing interest in smart materials, the utilization of shunted piezoceramics for dynamic vibration control has gained significant attention due to their unique characteristics, such as the ability to absorb strain energy from vibrating systems and convert it into electrical energy. Designing and analyzing the behavior of structures in hybrid mitigation/harvesting conditions, considering both reliability and performance, pose challenges. This paper aims to achieve optimal design parameters for the structure by employing a multiobjective optimization approach that strikes a compromise between maximizing harvested power and minimizing structural damage. To evaluate the effectiveness of the design, topology optimization was conducted in three different cases to compare the results. By systematically exploring the design space, these cases provide insights into the influence of various parameters on the structural performance. In addition, to enhance computational efficiency, the structure was represented as a metamodel using neural networks. This approach enables rapid evaluation and prediction of the structure’s behavior, facilitating the optimization process. By integrating multiobjective optimization, topology optimization, and metamodeling techniques, this study aims to provide valuable insights into the optimal design of structures that simultaneously incorporate shunt circuitry for vibration control and energy harvesting, leading to improved performance and reliability.
{"title":"Topology optimization of smart structures to enhance the performances of vibration control and energy harvesting","authors":"J P Sena, A M G de Lima, N Bouhaddi, N Kacem","doi":"10.1088/1361-665x/ad69ea","DOIUrl":"https://doi.org/10.1088/1361-665x/ad69ea","url":null,"abstract":"With the growing interest in smart materials, the utilization of shunted piezoceramics for dynamic vibration control has gained significant attention due to their unique characteristics, such as the ability to absorb strain energy from vibrating systems and convert it into electrical energy. Designing and analyzing the behavior of structures in hybrid mitigation/harvesting conditions, considering both reliability and performance, pose challenges. This paper aims to achieve optimal design parameters for the structure by employing a multiobjective optimization approach that strikes a compromise between maximizing harvested power and minimizing structural damage. To evaluate the effectiveness of the design, topology optimization was conducted in three different cases to compare the results. By systematically exploring the design space, these cases provide insights into the influence of various parameters on the structural performance. In addition, to enhance computational efficiency, the structure was represented as a metamodel using neural networks. This approach enables rapid evaluation and prediction of the structure’s behavior, facilitating the optimization process. By integrating multiobjective optimization, topology optimization, and metamodeling techniques, this study aims to provide valuable insights into the optimal design of structures that simultaneously incorporate shunt circuitry for vibration control and energy harvesting, leading to improved performance and reliability.","PeriodicalId":21656,"journal":{"name":"Smart Materials and Structures","volume":"10 1","pages":""},"PeriodicalIF":4.1,"publicationDate":"2024-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142178703","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-14DOI: 10.1088/1361-665x/ad6ab8
M Tixier, J Pouget
Electroactive polymers are smart materials that can be used as actuators, sensors, or energy harvesters. We focus on a pseudo trilayer based on PEDOT, a semiconductor polymer: the central part consists of two interpenetrating polymers and PEDOT is polymerized on each side; the whole blade is saturated with an ionic liquid. A pseudo trilayer is obtained, the two outer layers acting as electrodes. When an electric field is applied, the cations move towards the negative electrode, making it swell, while the volume decreases on the opposite side; this results in the bending of the strip. Conversely, the film deflection generates an electric potential difference between the electrodes. We model this system and establish its constitutive relations using the thermodynamics of irreversible processes; we obtain a Kelvin–Voigt stress–strain relation and generalized Fourier’s and Darcy’s laws. We validate our model in the static case: we apply the latter to a cantilever blade subject to a continuous potential electric difference at the constant temperature. We draw the profiles of the different quantities and evaluate the tip displacement and the blocking force. Our results agree with the experimental data published in the literature.
{"title":"Modeling of an electro-active pseudo-trilayer based on PEDOT, a semi-conductor polymer","authors":"M Tixier, J Pouget","doi":"10.1088/1361-665x/ad6ab8","DOIUrl":"https://doi.org/10.1088/1361-665x/ad6ab8","url":null,"abstract":"Electroactive polymers are smart materials that can be used as actuators, sensors, or energy harvesters. We focus on a pseudo trilayer based on PEDOT, a semiconductor polymer: the central part consists of two interpenetrating polymers and PEDOT is polymerized on each side; the whole blade is saturated with an ionic liquid. A pseudo trilayer is obtained, the two outer layers acting as electrodes. When an electric field is applied, the cations move towards the negative electrode, making it swell, while the volume decreases on the opposite side; this results in the bending of the strip. Conversely, the film deflection generates an electric potential difference between the electrodes. We model this system and establish its constitutive relations using the thermodynamics of irreversible processes; we obtain a Kelvin–Voigt stress–strain relation and generalized Fourier’s and Darcy’s laws. We validate our model in the static case: we apply the latter to a cantilever blade subject to a continuous potential electric difference at the constant temperature. We draw the profiles of the different quantities and evaluate the tip displacement and the blocking force. Our results agree with the experimental data published in the literature.","PeriodicalId":21656,"journal":{"name":"Smart Materials and Structures","volume":"60 1","pages":""},"PeriodicalIF":4.1,"publicationDate":"2024-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142178704","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-14DOI: 10.1088/1361-665x/ad6bd7
Dingfeng Yang, Hongxu Xia, Yurou Tang, Mingyu Pi, Yuanyuan Li
Searching negative thermal expansion (NTE) materials is challenging. Herein, hexagonal VF3 is predicted as a new NTE material for the first time. VF3 displays NTE property in the temperature range from 0 to 380 K, and the minimum NTE coefficient(α) is approximately −4.68 × 10−6 K−1 at 120 K. The NTE mechanism was ascribed to the vibrations of F atom with larger atomic displacement parameters, which dominates the negative Grüneisen parameters. The difference of minimum NTE coefficient between VF3 and TiF3 might be caused by their different chemical bond strength between Ti–F and V–F. This research provides a deeper understanding between NTE and crystal structure.
{"title":"Negative thermal expansion in hexagonal VF3 predicted by first-principles calculation","authors":"Dingfeng Yang, Hongxu Xia, Yurou Tang, Mingyu Pi, Yuanyuan Li","doi":"10.1088/1361-665x/ad6bd7","DOIUrl":"https://doi.org/10.1088/1361-665x/ad6bd7","url":null,"abstract":"Searching negative thermal expansion (NTE) materials is challenging. Herein, hexagonal VF<sub>3</sub> is predicted as a new NTE material for the first time. VF<sub>3</sub> displays NTE property in the temperature range from 0 to 380 K, and the minimum NTE coefficient(<italic toggle=\"yes\">α</italic>) is approximately −4.68 × 10<sup>−6</sup> K<sup>−1</sup> at 120 K. The NTE mechanism was ascribed to the vibrations of F atom with larger atomic displacement parameters, which dominates the negative Grüneisen parameters. The difference of minimum NTE coefficient between VF<sub>3</sub> and TiF<sub>3</sub> might be caused by their different chemical bond strength between Ti–F and V–F. This research provides a deeper understanding between NTE and crystal structure.","PeriodicalId":21656,"journal":{"name":"Smart Materials and Structures","volume":"41 1","pages":""},"PeriodicalIF":4.1,"publicationDate":"2024-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142178705","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Low acoustic energy conversion efficiency is a major challenge for air-coupled ultrasonic technology. In the determination of the lift-off distance of air-coupled sensors, there is a balance between the acoustic energy attenuation and the difficulty of extracting defect information. In this study, an air-coupled local defect resonance (LDR) technique with coda wave analysis is proposed for the nondestructive evaluation of debonding in composites. A sensor consisting of 19 elements was used to simultaneously excite and receive ultrasonic waves. Air-coupled LDR experiments were conducted on the two types of composite structures. The effects of sensor lift-off distance and coda wave analysis on the performance of the LDR technique were investigated. It was found that the sensor lift-off distance and the coda wave analysis had a significant effect on the defect detection capability of the LDR technique. For composites, the optimal sensor lift-off distance was found to be between 3.5λ and 5.5λ, where λ is the wavelength. Compared to multiple reflection echoes, the coda waves are more suitable for identifying the damage in composites. The proposed non-contact ultrasonic technique effectively reduces the required incident acoustic energy and can be used for efficient detection of debonding in composites.
{"title":"Nondestructive evaluation of debonding in composites using air-coupled coda wave analysis and local defect resonance techniques","authors":"Zhiqiang Li, Jingpin Jiao, Xiangfeng Zheng, Xiaojun Hao, Cunfu He, Bin Wu","doi":"10.1088/1361-665x/ad6cba","DOIUrl":"https://doi.org/10.1088/1361-665x/ad6cba","url":null,"abstract":"Low acoustic energy conversion efficiency is a major challenge for air-coupled ultrasonic technology. In the determination of the lift-off distance of air-coupled sensors, there is a balance between the acoustic energy attenuation and the difficulty of extracting defect information. In this study, an air-coupled local defect resonance (LDR) technique with coda wave analysis is proposed for the nondestructive evaluation of debonding in composites. A sensor consisting of 19 elements was used to simultaneously excite and receive ultrasonic waves. Air-coupled LDR experiments were conducted on the two types of composite structures. The effects of sensor lift-off distance and coda wave analysis on the performance of the LDR technique were investigated. It was found that the sensor lift-off distance and the coda wave analysis had a significant effect on the defect detection capability of the LDR technique. For composites, the optimal sensor lift-off distance was found to be between 3.5<italic toggle=\"yes\">λ</italic> and 5.5<italic toggle=\"yes\">λ</italic>, where <italic toggle=\"yes\">λ</italic> is the wavelength. Compared to multiple reflection echoes, the coda waves are more suitable for identifying the damage in composites. The proposed non-contact ultrasonic technique effectively reduces the required incident acoustic energy and can be used for efficient detection of debonding in composites.","PeriodicalId":21656,"journal":{"name":"Smart Materials and Structures","volume":"11 1","pages":""},"PeriodicalIF":4.1,"publicationDate":"2024-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142178701","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In addition to the distinctive features of tunable Poisson’s ratio from positive to negative and low stress concentration, the perforated auxetic metamaterials by peanut-shaped cuts have exhibited excellent phononic crystal (PNC) behavior as well for elastic wave manipulation. Thus they have attracted much attention in vibration suppression for dynamic applications. However, traditional structural designs of the auxetic PNCs considerably depend on designers’ experience or inspiration to fulfill the desired multi-objective bandgap properties through extensive trial and error. Hence, developing a more efficient and robust inverse design method remains challenging to accelerate the creation of auxetic PNCs and improve their performance. To shorten this gap, a new machine learning (ML) framework consisting of double back propagation neural network (BPNN) modules is developed in this work to produce desired configurations of the auxetic PNCs matching the customized bandgap. The first inverse BPNN module is trained to establish a logical mapping from the bandgap properties to the structural parameters, and then the second forward BPNN module is introduced to give the new property prediction by using the design configurations generated from the former. The error between the new predictions and the desired target properties is minimized through a limited number of iterations to produce the final optimal objective configurations. The results indicate that the perforated auxetic metamaterials behave relatively wide complete bandgap and the present ML model is effective in designing them with specific bandgaps within or beyond the given dataset. The study provides a powerful tool for designing and optimizing the perforated auxetic metamaterials in dynamic environment.
{"title":"Data-driven inverse design of the perforated auxetic phononic crystals for elastic wave manipulation","authors":"Hongyuan Liu, Yating Gao, Yongpeng Lei, Hui Wang, Qinxi Dong","doi":"10.1088/1361-665x/ad6c05","DOIUrl":"https://doi.org/10.1088/1361-665x/ad6c05","url":null,"abstract":"In addition to the distinctive features of tunable Poisson’s ratio from positive to negative and low stress concentration, the perforated auxetic metamaterials by peanut-shaped cuts have exhibited excellent phononic crystal (PNC) behavior as well for elastic wave manipulation. Thus they have attracted much attention in vibration suppression for dynamic applications. However, traditional structural designs of the auxetic PNCs considerably depend on designers’ experience or inspiration to fulfill the desired multi-objective bandgap properties through extensive trial and error. Hence, developing a more efficient and robust inverse design method remains challenging to accelerate the creation of auxetic PNCs and improve their performance. To shorten this gap, a new machine learning (ML) framework consisting of double back propagation neural network (BPNN) modules is developed in this work to produce desired configurations of the auxetic PNCs matching the customized bandgap. The first inverse BPNN module is trained to establish a logical mapping from the bandgap properties to the structural parameters, and then the second forward BPNN module is introduced to give the new property prediction by using the design configurations generated from the former. The error between the new predictions and the desired target properties is minimized through a limited number of iterations to produce the final optimal objective configurations. The results indicate that the perforated auxetic metamaterials behave relatively wide complete bandgap and the present ML model is effective in designing them with specific bandgaps within or beyond the given dataset. The study provides a powerful tool for designing and optimizing the perforated auxetic metamaterials in dynamic environment.","PeriodicalId":21656,"journal":{"name":"Smart Materials and Structures","volume":"14 1","pages":""},"PeriodicalIF":4.1,"publicationDate":"2024-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142178700","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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