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Bioinspired Strategies for Excellent Mechanical Properties of Composites

Xianchang Peng, Binjie Zhang, Ze Wang, Wenbo Su, Shichao Niu, Zhiwu Han & Luquan Ren

Journal of Bionic Engineering. 2022 (5): 1203-1228. DOI: 10.1007/s42235-022-00199-9

摘要 ( 201 )

Developing high-performance composite materials is of great significance as a strong support for high-end manufacturing. However, the design and optimization of composite materials lack a theoretical basis and guidance scheme. Compared with traditional composite materials, natural materials are composed of relatively limited components but exhibit better mechanical properties through ingenious and reasonable synthetic strategies. Based on this, learning from nature is considered to be an effective way to break through the bottleneck of composite design and preparation. In this review, the recent progress of natural composites with excellent properties is presented. Multiple factors, including structures, components and interfaces, are first summarized to reveal the strategies of natural materials to achieve outstanding mechanical properties. In addition, the manufacturing technologies and engineering applications of bioinspired composite materials are introduced. Finally, some scientific challenges and outlooks are also proposed to promote next-generation bioinspired composite materials.

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Multi-material Bio-inspired Soft Octopus Robot for Underwater Synchronous Swimming

Faheem Ahmed, Muhammad Waqas, Bushra Shaikh, Umair Khan, Afaque Manzoor Soomro, Suresh Kumar, Hina Ashraf, Fida Hussain Memon & Kyung Hyun Choi

Journal of Bionic Engineering. 2022 (5): 1229-1241. DOI: 10.1007/s42235-022-00208-x

摘要 ( 184 )

Inspired by the simple yet amazing morphology of the Octopus, we propose the design, fabrication, and characterization of multi-material bio-inspired soft Octopus robot (Octobot). 3D printed molds for tentacles and head were used. The tentacles of the Octobot were casted using Ecoflex-0030 while head was fabricated using relatively flexible material, i.e., OOMOO-25. The head is attached to the functionally responsive tentacles (each tentacle is of 79.12 mm length and 7 void space diameter), whereas Shape Memory Alloy (SMA) muscle wires of 0.5 mm thickness are used in Octobot tentacles for dual thrust generation and actuation of Octobot. The tentacles were separated in two groups and were synchronously actuated. Each tentacle of the developed Octobot contains a pair of SMA muscles (SMA-α and SMA-β). SMA-α muscles being the main actuator, was powered by 9 V, 350 mA power supply, whereas SMA-β was used to provide back thrust and thus helps to increase the actuation frequency. Simulation work of the proposed model was performed in the SolidWorks environment to verify the vertical velocity using the octopus tentacle actuation. The design morphology of Octobot was optimized using simulation and TRACKER software by analyzing the experimental data of angle, displacement, and velocity of real octopus. The as-developed Octobot can swim at variable frequencies (0.5–2 Hz) with the average speed of 25 mm/s (0.5 BLS). Therefore, the proposed soft Octopus robot showed an excellent capability of mimicking the gait pattern of its natural counterpart.

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Intelligent Knee Prostheses: A Systematic Review of Control Strategies

Linrong Li, Xiaoming Wang, Qiaoling Meng, Changlong Chen, Jie Sun & Hongliu Yu

Journal of Bionic Engineering. 2022 (5): 1242-1260. DOI: 10.1007/s42235-022-00169-1

摘要 ( 221 )

The intelligent knee prosthesis is capable of human-like bionic lower limb control through advanced control systems and artificial intelligence algorithms that will potentially minimize gait limitations for above-knee amputees and facilitate their reintegration into society. In this paper, we sum up the control strategies corresponding to the prevailing control objectives (position and impedance) of the current intelligent knee prosthesis. Although these control strategies have been successfully implemented and validated in relevant experiments, the existing deficiencies still fail to achieve optimal performance of the controllers, which complicates the definition of a standard control method. Before a mature control system can be developed, it is more important to realize the full potential for the control strategy, which requires upgrading and refining the relevant key technologies based on the existing control methods. For this reason, we discuss potential areas for improvement of the prosthetic control system based on the summarized control strategies, including intent recognition, sensor system, prosthetic evaluation, and parameter optimization algorithms, providing future directions toward optimizing control strategies for the next generation of intelligent knee prostheses.

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Experimental Study on the Improvement of Yaw Stability by Coordination Control between the Caudal Fin and Anal Fin

Jiang Ding, Changzhen Zheng, Chaocheng Song, Qiyang Zuo, Yaohui Xu, Bingbing Dong, Jiaxu Cui, Kai He & Fengran Xie

Journal of Bionic Engineering. 2022 (5): 1261-1271. DOI: 10.1007/s42235-022-00201-4

摘要 ( 260 )

Due to the unique locomotion, the head-shaking problem of biomimetic robotic fish inevitably occurs during rectilinear locomotion, which strongly hinders its practical applications. In this paper, we experimentally study this problem by proposing the method of coordination control between the caudal fin and anal fin. First, an untethered biomimetic robotic fish, equipped with an anal fin, a caudal fin and two pectoral fins, is developed as the experimental platform. Second, a Central Pattern Generator (CPG)-based controller is used to coordinate the motions of the anal fin and caudal fin. Third, extensive experiments are conducted to explore different combinations of the flapping frequencies, the flapping amplitudes, and the phase differences between the anal fin and caudal fin. Notably, through proper control of the anal fin, the amplitude of the yaw motion can be as small as 4.32°, which sees a 65% improvement compared to the scenario without anal fin, and a 57% improvement compared to that with a stationary anal fin. This paper provides a novel way to alleviate the head-shaking problem for biomimetic robotic fish, and first test this method on an untethered, freely swimming robotic platform, which can shed light on the development of underwater robotics.

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Snake-worm: A Bi-modal Locomotion Robot

Zhouwei Du, Hongbin Fang & Jian Xu

Journal of Bionic Engineering. 2022 (5): 1272-1287. DOI: 10.1007/s42235-022-00197-x

摘要 ( 202 )

Inspired by the morphology characteristics and the locomotion mechanisms of the earthworm, and the snakes’ morphology characteristics and motivated by the demands for multi-modal locomotion robots in variable working environments, this paper presents a novel bi-modal robot named as Snake-Worm Locomotion Robot (SWL-Robot). Two fundamentally different locomotion mechanisms, the earthworm’s peristaltic rectilinear locomotion and the snake’s lateral undulation, are synthesized in the SWL-Robot design. In detail, the SWL-Robot consists of six earthworm-like body segments interconnected by rotational joints and a head segment equipped with a couple of independently driven wheels. By actuating the segments following a peristaltic wave-like gait, the robot as a whole could perform earthworm-like rectilinear crawling. The robot could also perform snake-like undulatory locomotion driven by differential motions of the wheels at the head segment. To understand the relationship between the design parameters and the robotic locomotion performance, kinematic models of the SWL-Robot corresponding to the two locomotion modes are developed. Rich locomotion behaviors of the SWL-Robot are achieved, including the peristaltic locomotion inside a tube, multiple planar motions on a flat surface, and a hybrid motion that switches between the tube and the flat surface. It shows that the measured trajectories of the SWL-Robot agree well with the theoretical predictions. The SWL-Robot is promising to be implemented in tasks where both tubular and flat environments may be encountered.

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Cockroach-inspired Traversing Narrow Obstacles for a Sprawled Hexapod Robot

Xingguo Song, Jiajun Pan, Faming Lin, Xiaolong Zhang, Chunjun Chen & Danshan Huang

Journal of Bionic Engineering. 2022 (5): 1288-1301. DOI: 10.1007/s42235-022-00218-9

摘要 ( 192 )

Inspired by the cockroach’s use of a pitch-roll mode traverses through narrow obstacles, we improve the RHex-style robot by adding two sprawl joints to adjust the body posture, and propose a novel pitch-roll approach that enables an RHex-style robot to traverse through two cylindrical obstacles with a spacing of 90 mm, about 54% body width. First, the robot can pitch up against the obstacle on the one side by the cooperation of its rear and middle legs. Then, the robot rotates one side rear leg to kick the ground fast, meanwhile the sprawl joint on the other side rotates inward to make the robot roll and fall forward. Finally, the robot can rotate the legs on the ground to move the body forward until it crosses the obstacles. In this article, both cylinder and rectangular columns are considered as the narrow obstacles for traversing. The experiments are demonstrated by using the proposed approach, and the results show that the robot can smoothly traverse through different narrow spaces.

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A Novel Movement Behavior Control Method for Carp Robot through the Stimulation of Medial Longitudinal Fasciculus Nucleus of Midbrain

Yang Zhao, Yong Peng, Yudong Wen, Lingjun Han, Hui Zhang, Zheng Zhao & Xiaoyue Liu

Journal of Bionic Engineering. 2022 (5): 1302-1313. DOI: 10.1007/s42235-022-00211-2

摘要 ( 207 )

Biological robot is a kind of creature controlled by human beings by applying intervention signals through control technology to regulate biological behavior. At present, the research on bio-robot mainly focuses on terrestrial mammals and insects, while the research on aquatic animal robot is less. Early studies have shown that the medial longitudinal fasciculus nucleus (NFLM) of carp midbrain was related to tail wagging, but the research has not been applied to the navigation control of the carp robot. The purpose of this study is to realize the quantitative control of the forward and steering behavior of the carp robot by NFLM electrical stimulation. Under the condition of no craniotomy, brain electrode was implanted into the NFLM of the carp midbrain, and the underwater control experiment was carried out by applying different electrical stimulation parameters. Using the ImageJ software and self-programmed, the forward motion speed and steering angle of steering motion of the carp robot before and after being stimulated were calculated. The experimental results showed for the carp robot that was induced the steering motion, the left and right steering motion of 30° to 150° could be achieved by adjusting the stimulation parameters, for the carp robot that was induced the forward motion, the speed of forward motion could be controlled to reach 100 cm/s. The research lays a foundation for the accurate control of the forward and steering motion of the aquatic animal robot.

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Optimization and Experimental Study of Bionic Compliant End-effector for Robotic Cherry Tomato Harvesting

Huaibei Xie, Deyi Kong & Qiong Wang

Journal of Bionic Engineering. 2022 (5): 1314-1333. DOI: 10.1007/s42235-022-00202-3

摘要 ( 199 )

High harvesting success rate is part of the key technologies for robotic cherry tomato harvesting, which is closely related to the structural design of the end-effector. To obtain a high success rate of fruit harvesting, this paper presents a compliant end-effector with bio-inspired tarsus compliant gripper inspired by the structure and mechanics of the tarsal chain in the Serica orientalis Motschulsky. Response Surface Methodology (RSM) based on Box Behnken Design (BBD) technique has been used to optimize the key structural parameters of the bionic compliant end-effector for achieving the expected results in pulling pattern for robotic cherry tomato harvesting. Experiments were designed by maintaining three levels of four process parameters—Length of the Offset Segment Tarsomere (OSTL), Angle of the Inclined Segment Tarsomere (ISTA), Thickness of the Extended Segment Tarsomere (ESTT) and Length of the Extended Segment Tarsomere (ESTL). According to the optimization analysis results, the best parameter combination is OSTL 23 mm, ISTA 14°, ESTT 5.0 mm, ESTL 23 mm. Besides, the harvesting performance of the optimized bionic compliant end-effector was verified by experiments. The results indicated the harvesting success rate of fruits with different equatorial diameters was not less than 76%.

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A Fully Soft Bionic Grasping Device with the Properties of Segmental Bending Shape and Automatically Adjusting Grasping Range

Lingjie Gai & Xiaofeng Zong

Journal of Bionic Engineering. 2022 (5): 1334-1348. DOI: 10.1007/s42235-022-00209-w

摘要 ( 170 )

In this paper, we propose a fully Soft Bionic Grasping Device (SBGD), which has advantages in automatically adjusting the grasping range, variable stiffness, and controllable bending shape. This device consists of soft gripper structures and a soft bionic bracket structure. We adopt the local thin-walled design in the soft gripper structures. This design improves the grippers’ bending efficiency, and imitate human finger’s segmental bending function. In addition, this work also proposes a pneumatic soft bionic bracket structure, which not only can fix grippers, but also can automatically adjust the grasping space by imitating the human adjacent fingers’ opening and closing movements. Due to the above advantages, the SBGD can grasp larger or smaller objects than the regular grasping devices. Particularly, to grasp small objects reliably, we further present a new Pinching Grasping (PG) method. The great performance of the fully SBGD is verified by experiments. This work will promote innovative development of the soft bionic grasping robots, and greatly meet the applications of dexterous grasping multi-size and multi-shape objects.

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Development of Novel Hybrid Hand Formed by a Parallel Wrist and Three Soft-flexible Fingers

Yi Lu, Zefeng Chang & Yang Lu

Journal of Bionic Engineering. 2022 (5): 1349-1358. DOI: 10.1007/s42235-022-00206-z

摘要 ( 179 )

A prototype of a novel hybrid hand is developed by combing a parallel wrist with three flexible fingers. Its dynamics model is established, its grabbed forces are measured, and its grabbing performances are analyzed. First, Jacobian and Hessian matrices of the moving platform in the parallel wrist are derived, the kinematics formulas for solving the general velocity and the general acceleration of the moving platform are derived. Second its dynamics model is established for solving the dynamic actuation forces, the dynamic constrained forces of the developed hybrid hand. Third, its simulation mechanism is constructed in Matlab, and the theoretical solutions of the kinematics and the dynamics of the developed hybrid hand are verified to be correct using its simulation mechanism. Finally, when objects with different mass are grabbed by prototype of hybrid hand in different poses, the grabbed forces are measured, and the grabbing performances are discovered and analyzed to verify its merits.

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Integral Real-time Locomotion Mode Recognition Based on GA-CNN for Lower Limb Exoskeleton

Jiaqi Wang, Dongmei Wu, Yongzhuo Gao, Xinrui Wang, Xiaoqi Li, Guoqiang Xu & Wei Dong

Journal of Bionic Engineering. 2022 (5): 1359-1373. DOI: 10.1007/s42235-022-00230-z

摘要 ( 165 )

The wearable lower limb exoskeleton is a typical human-in-loop human–robot coupled system, which conducts natural and close cooperation with the human by recognizing human locomotion timely. Requiring subject-specific training is the main challenge of the existing approaches, and most methods have the problem of insufficient recognition. This paper proposes an integral subject-adaptive real-time Locomotion Mode Recognition (LMR) method based on GA-CNN for a lower limb exoskeleton system. The LMR method is a combination of Convolutional Neural Networks (CNN) and Genetic Algorithm (GA)-based multi-sensor information selection. To improve network performance, the hyper-parameters are optimized by Bayesian optimization. An exoskeleton prototype system with multi-type sensors and novel sensing-shoes is used to verify the proposed method. Twelve locomotion modes, which composed an integral locomotion system for the daily application of the exoskeleton, can be recognized by the proposed method. According to a series of experiments, the recognizer shows strong comprehensive abilities including high accuracy, low delay, and sufficient adaption to different subjects.

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Design and Implementation of a Rehabilitation Upper-limb Exoskeleton Robot Controlled by Cognitive and Physical Interfaces

Arturo González-Mendoza, Ivett Quiñones-Urióstegui, Sergio Salazar-Cruz, Alberto-Isaac Perez-Sanpablo, Ricardo López-Gutiérrez & Rogelio Lozano

Journal of Bionic Engineering. 2022 (5): 1374-1391. DOI: 10.1007/s42235-022-00214-z

摘要 ( 182 )

This paper presents an upper limb exoskeleton that allows cognitive (through electromyography signals) and physical user interaction (through load cells sensors) for passive and active exercises that can activate neuroplasticity in the rehabilitation process of people who suffer from a neurological injury. For the exoskeleton to be easily accepted by patients who suffer from a neurological injury, we used the ISO9241-210:2010 as a methodology design process. As the first steps of the design process, design requirements were collected from previous usability tests and literature. Then, as a second step, a technological solution is proposed, and as a third step, the system was evaluated through performance and user testing. As part of the technological solution and to allow patient participation during the rehabilitation process, we have proposed a hybrid admittance control whose input is load cell or electromyography signals. The hybrid admittance control is intended for active therapy exercises, is easily implemented, and does not need musculoskeletal modeling to work. Furthermore, electromyography signals classification models and features were evaluated to identify the best settings for the cognitive human–robot interaction.

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Design and Analysis of a 2-DOF Actuator with Variable Stiffness Based on Leaf Springs

ShangKui Yang, Peng Chen, DongQi Wang, Yi Yu & YuWang Liu

Journal of Bionic Engineering. 2022 (5): 1392-1404. DOI: 10.1007/s42235-022-00205-0

摘要 ( 166 )

Variable Stiffness Actuator (VSA) is the core mechanism to achieve physical human–robot interaction, which is an inevitable development trend in robotic. The existing variable stiffness actuators are basically single degree-of-freedom (DOF) rotating joints, which are achieving multi-DOF motion by cascades and resulting in complex robot body structures. In this paper, an integrated 2-DOF actuator with variable stiffness is proposed, which could be used for bionic wrist joints or shoulder joints. The 2-DOF motion is coupling in one universal joint, which is different from the way of single DOF actuators cascade. Based on the 2-DOF orthogonal motion generated by the spherical wrist parallel mechanism, the stiffness could be adjusted by varying the effective length of the springs, which is uniformly distributed in the variable stiffness unit. The variable stiffness principle, the model design, and theoretical analysis of the VSA are discussed in this work. The independence of adjusting the equilibrium position and stiffness of the actuator is validated by experiments. The results show that the measured actuator characteristics are sufficiently matched the theoretical values. In the future, VSA could be used in biped robot or robotic arm, ensuring the safety of human–robot interaction.

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Utilization of Whale-inspired Leading-edge Tubercles for Airfoil Noise Reduction

Weijie Chen, Liangji Zhang, Liangfeng Wang, Zuojun Wei & Weiyang Qiao

Journal of Bionic Engineering. 2022 (5): 1405-1421. DOI: 10.1007/s42235-022-00210-3

摘要 ( 211 )

Numerical studies are conducted to explore the noise reduction effect of leading-edge tubercles inspired by humpback whale flippers. Large eddy simulations are performed to solve the flow field, while the acoustic analogy theory is used for noise prediction. In this paper, a baseline airfoil with a straight leading-edge and three bionic airfoils with tubercled leading-edges are simulated. The tubercles have sinusoidal profiles and the profiles are determined by the tubercle wavelength and amplitude. The tubercles used in this study have a fixed wavelength of 0.1c with three different amplitudes of 0.1c, 0.15c and 0.2c, where c is the mean chord of the airfoil. The freestream velocity is set to 40 m/s and the chord based Reynolds number is 400,000. The predicted flow field and acoustic field of the baseline airfoil are compared against the experiments and good agreements are found. A considerable noise reduction level is achieved by the leading-edge tubercles and the tubercle with larger amplitude can obtain better noise reduction. The underlying flow mechanisms responsible for the noise reduction are analyzed in detail.

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Effects of Morphological Integrity of Secondary Feather on Their Drag Reduction in Pigeons

Qian Li, Huan Shen, Qingfei Han, Aihong Ji, Zhendong Dai & Stanislav N. Gorb

Journal of Bionic Engineering. 2022 (5): 1422-1438. DOI: 10.1007/s42235-022-00203-2

摘要 ( 184 )

Flight feathers of birds interact with the air flow during flight. How the observed low drag and high lift values at wind speeds from 9.0 to 19.8 m/s can be achieved due to the feather aerodynamics remains unknown. In the present paper, we tested and compared morphological changes, drag reduction and flow visualization results of intact, damaged, and artificial feathers at different wind speeds in a wind tunnel. Through the analysis of the drag force and resultant force angle, we proved that the integrity of feathers, whose barbs are usually closely interconnected, played an important role in the drag, which potentially triggers excellent drag reduction performance. The wind tunnel tests indicated that intact secondary feathers had a surprisingly high maximum drag reduction property at v?=?9 m/s compared with the feathers, where the integrity of barbs was damaged. The hook cascades facilitated elasticity under pressure and suitable permeability in an intact feather, when the hooks were interlocked. It was indicated that the suitable permeability of intact feathers would prevent flow separation and reduce drag force at low wind speed; at high wind speed, elasticity under pressure and suitable permeability in an intact feather would facilitate strong squeezing effect, helping feathers withstand larger aerodynamic forces to which they might be subjected during flight. It was revealed that the intact secondary feather is a compromise between strong lift generation and drag reduction, which has a great significance for the bird’s flight.

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High-performance Multilayer Flexible Piezoresistive Pressure Sensor with Bionic Hierarchical and Anisotropic Structure

Meng Wang, Yue Yu, Yunhong Liang, Zhiwu Han, Chunbao Liu, Suqian Ma, Zhaohua Lin & Lei Ren

Journal of Bionic Engineering. 2022 (5): 1439-1448. DOI: 10.1007/s42235-022-00219-8

摘要 ( 201 )

Flexible pressure sensor that enables detection of multimodal signals has greater advantages in human–computer interaction, medical/health care, and other applications. To make a versatile flexible pressure sensor, hierarchical and anisotropy structure are key features to improve sensing performance and realize multi-signal detection. However, traditional flexible sensors usually have narrow linear range and single signal detection capability. Herein, a highly sensitive flexible piezoresistive pressure sensor which has broad linear range of pressure is developed by replicating one dimensional microstructures from reed leaf and using multilayer superposition of micropatterned polydimethylsiloxane (m-PDMS). Through superposing 4 layers of parallel micropatterned constructive substrates, the multilayer piezoresistive pressure sensor exhibits a high sensitivity of 2.54 kPa?1, a fast response time of 30 ms, and a broad linear range of 107 kPa. The flexible piezoresistive pressure sensor is also highly robust: there is no fatigue after testing for at least 1000 cycles. Due to the specific anisotropy of the micro-structure, the sensor can measure the tangential force in different directions. It permits multimode signal detection, including pressure, tangential force, and deformation. The versatile flexible pressure sensor enables effective monitoring of multisignals, it reveals great potential for medical and health care, flexible human–computer interaction, and intelligent robot.

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The Effects of a Novel Multicomponent Transition Metal Dichalcogenide on Nervous System Regeneration

Nahid Askari, Mohammad Bagher Askari, Ali Shafieipour, Behnaz Salek Esfahani & Morteza Hadizadeh

Journal of Bionic Engineering. 2022 (5): 1449-1459. DOI: 10.1007/s42235-022-00215-y

摘要 ( 203 )

In regenerative medicine, a scaffold is needed to provide physical support for the growth of cells at the injury site. Carbon composites are also widely used in biomedicine. This research aimed to see if (MoWCu)S/rGO could be used in peripheral and central neural regeneration as a carbon-based nanomaterial. This material was created using a one-step hydrothermal process. We used Scanning Electron Microscopy with Energy Dispersive X-ray analysis (SEM–EDX), X-ray diffraction, and Field-Emission Scanning Electron Microscopy (FE-SEM) to describe it. The researchers used animal models of spinal cord injury and sciatic nerve injury to assess its effect as a scaffold of anti-inflammatory and electrical conductivity. The Basso Beattie Bresnahan locomotor rating scale and von Frey Filament were used to assess neuronal function after (MoWCu)S/rGO transplantation. In addition, the expression of p75 NTR and neurotrophic factors (BDNF, NT3, and NGF) mRNA in the experimental rats nerve was compared to the normal ones using Real-Time RT-qPCR. In the experimental groups, the use of (MoWCu)S/rGO resulted in a significant increase in neurotrophic factor gene expression, while p75 NTR was inversely decreased. In conclusion, we found that the nerve regeneration activity of the (MoWCu)S/rGO scaffold in rat models significantly increased motor function recovery in the treated groups. Furthermore, the current study explained the response of this composite to inflammatory neurodegenerative diseases. (MoWCu)S incorporation in graphene is thought to have excellent properties and may be used in regenerative medicine.

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Modeling the Wettability of Microstructured Hydrophobic Surface Using Multiple-relaxation-time Lattice Boltzmann Method

Lei Tian & Liuchao Qiu

Journal of Bionic Engineering. 2022 (5): 1460-1471. DOI: 10.1007/s42235-022-00204-1

摘要 ( 177 )

Wetting properties are significant for a hydrophobic surface and normally characterized by the equilibrium contact angle. In this manuscript, a mesoscopic method based on multiphase multiple-relaxation-time Lattice Boltzmann method has been presented and applied to simulate the contact angle at three-phase interfaces of a solid surface with micro-pillar structure. The influence of different parameters including pillar height, pillar width, inter-pillar spacing, intrinsic contact angle and the volume of the liquid drop on the equilibrium contact angle has been comprehensively investigated. The effect of geometry parameters of the micro-pillar structure on the wetting transition from Cassie–Baxter state to Wenzel state has also been studied. The results indicate that when the inter-pillar spacing is less than a certain value or the pillar height is greater than a certain value, the contact form between the droplet and the surface satisfies the Cassie–Baxter state. When the contact form satisfies the Cassie–Baxter state, the contact angle gradually increases with the increase of the inter-pillar spacing; the contact angle does not change significantly with the pillar height; the contact angle gradually decreases and approaches the intrinsic contact angle with the pillar width increases. Moreover, the contact angle increases with the increase of the intrinsic contact angle, and the contact angle is not sensitive to the change of droplet volume when the droplet volume is between 0.5 and10 μl.

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Growth Ring-dependent Fracture Toughness of Sea Urchin Spines Estimated by Boundary Effect Model

Xiaona Liu, Simin Liang, Yingying Li, Hongmei Ji & Xiaowu Li

Journal of Bionic Engineering. 2022 (5): 1472-1480. DOI: 10.1007/s42235-022-00200-5

摘要 ( 178 )

Although the fracture behavior of sea urchin spines has been extensively investigated, there is as yet a lack of quantitative estimation on the effect of growth rings on the fracture properties of sea urchin spines. In sea urchin spines, much denser pores present in growth rings rather than porous layers. The tensile strength and fracture toughness of sea urchin spine samples with different numbers of growth rings are measured by the Boundary Effect Model (BEM). The experimental results of single-edge notched three-point bending tests indicate that the BEM is an appropriate method to estimate the fracture toughness of the present porous sea urchin spines, and the number of growth rings plays an important role in the fracture properties of spines. Specifically, the tensile strength and fracture toughness of sea urchin spines can be significantly improved with the increase in the number of growth rings, and their fracture toughness can even reach a relatively high value compared with some other porous materials with an identical porosity. The present research findings are expected to provide a fundamental insight into the design of high-performance bionic materials with a highly porous structure.

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Tribological and Physicochemical Analysis of Squid Pen High-density Polyethylene Biocomposite for Medical Application

Besma Sidia & Walid Bensalah

Journal of Bionic Engineering. 2022 (5): 1481-1492. DOI: 10.1007/s42235-022-00200-5

摘要 ( 167 )

High-Density Polyethylene (HDPE) wear debris generated in the hip joint prothesis leads to its loosening. The aim of this study was to evaluate the potential of Squid Pen (SP) on the tribological and physicochemical properties of HDPE matrix. Biocomposites filled with 0, 5, 10, 15 and 20 wt. % SP were elaborated by hot compression molding. Wear tests were carried out using a reciprocating pin-on-disc tribometer. Rockwell hardness, Fourier-Transform infra-red (FTIR) analysis, Scanning Electron Microscopy (SEM) of the biocomposite were analysed. FTIR analysis results of the biocomposites showed that an increase in the crystallinity rate was obtained with the addition of SP filler. Only 10 wt. % of SP has a significant effect on the hardness of the composite. The correlation between the friction coefficient and the wear resistance of the composite was investigated. The 5 wt. % SP-HDPE biocomposite has the lowest friction coefficient value with a decrease in the specific wear rate, compared to the unfilled HDPE. The SEM results showed that SP wear debris played an important role as a third roller body at the interface reducing the friction coefficient of the composite. It was concluded that the HDPE biocomposite could be successfully reinforced with 5 wt. % of SP.

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Performance Evaluation of Calcium Alkali-treated Oil Palm/Pineapple Fibre/Bio-phenolic Composites

Sameer A. Awad, Hassan Fouad, Eman M. Khalaf, N. Saba, Hom N. Dhakal, M. Jawaid & Othman Y. Alothman

Journal of Bionic Engineering. 2022 (5): 1493-1503. DOI: 10.1007/s42235-022-00198-w

摘要 ( 154 )

The utilisation of oil palm fibre (OPF) and pineapple leaf fibres (PALF) as reinforcement materials for bio-phenolic composites is growing especially in automotive lightweight applications. The major aim of this current study is to investigate the influence of alkali (Ca(OH)2 treatment on pure and hybrid composites. The effects of enhancements in chemical interactions were evaluated by the Fourier-Transform Infrared Spectrometer (FTIR). Dynamic Mechanical Analysis (DMA) and Thermogravimetric Analysis (TGA) performance of untreated reinforcements (OPF and PALF) and treated (OPF/OPF) composites at varying temperature and noted sufficient interfacial bonding contributing towards the improvements in thermal stability. From DMA results, the storage modulus improved with treated composites while the damping factor was reduced. Furthermore, the treated hybrid composites exhibited significant improvements in thermal stability compared to untreated fibre composites. The results indicated that alkali calcium hydroxide (Ca(OH2(:T) incorporation in hybrid composites (OPF/PALF) results in increased tensile strength and modulus among all composites. Similarly, the alkali-treated (Ca (OH)2)-treated pure composite (T/50%PALF), and hybrid composites (T/1OPF.1PALF) exhibited better flexural strength as compared with other composites. In contrast, the T/50% PALF showed higher flexural stress of 78.2 MPa, while the flexural modulus was recorded at 6503 MPa. It can be proposed from the findings of this study that the alkali treatment (5%Ca(OH)2) can be utilised to improve the strength and efficiency of agriculture biomass to be used as reinforcements in composites. Additionally, the hybridisation of bio-fibre composites has the potential as a novel variety of biodegradable and sustainable composites appropriate for several industrial and engineering applications.

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An Efficient Hybrid Model Based on Modified Whale Optimization Algorithm and Multilayer Perceptron Neural Network for Medical Classification Problems

Saeid Raziani, Sajad Ahmadian, Seyed Mohammad Jafar Jalali & Abdolah Chalechale

Journal of Bionic Engineering. 2022 (5): 1504-1521. DOI: 10.1007/s42235-022-00216-x

摘要 ( 164 )

Feedforward Neural Network (FNN) is one of the most popular neural network models that is utilized to solve a wide range of nonlinear and complex problems. Several models such as stochastic gradient descent have been developed to train FNNs. However, they mainly suffer from falling into local optima leading to reduce the accuracy of FNNs. Moreover, the convergence speed of training process depends on the initial values of weights and biases in FNNs. Generally, these values are randomly determined by most of the training models. To deal with these issues, in this paper, we develop a novel evolutionary algorithm by modifying the original version of Whale Optimization Algorithm (WOA). To this end, a nonlinear function is introduced to improve the exploration and exploitation phases in the search process of WOA. Then, the modified WOA is applied to automatically obtain the initial values of weights and biases in FNN leading to reduce the probability of falling into local optima. In addition, the FNN model trained by the modified WOA is used to develop a classification approach for medical diagnosis problems. Ten medical diagnosis datasets are utilized to evaluate the efficiency of the proposed method. Also, four evaluation metrics including accuracy, AUC, specificity, and sensitivity are used in the experiments to compare the performance of classification models. The experimental results demonstrate that the proposed method is better than other competing classification models due to achieving higher values of accuracy, AUC, specificity, and sensitivity metrics for the used datasets.

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A Hybrid Moth Flame Optimization Algorithm for Global Optimization

Saroj Kumar Sahoo & Apu Kumar Saha

Journal of Bionic Engineering. 2022 (5): 1522-1543. DOI: 10.1007/s42235-022-00207-y

摘要 ( 186 )

The Moth Flame Optimization (MFO) algorithm shows decent performance results compared to other meta-heuristic algorithms for tackling non-linear constrained global optimization problems. However, it still suffers from obtaining quality solution and slow convergence speed. On the other hand, the Butterfly Optimization Algorithm (BOA) is a comparatively new algorithm which is gaining its popularity due to its simplicity, but it also suffers from poor exploitation ability. In this study, a novel hybrid algorithm, h-MFOBOA, is introduced, which integrates BOA with the MFO algorithm to overcome the shortcomings of both the algorithms and at the same time inherit their advantages. For performance evaluation, the proposed h-MFOBOA algorithm is applied on 23 classical benchmark functions with varied complexity. The tested results of the proposed algorithm are compared with some well-known traditional meta-heuristic algorithms as well as MFO variants. Friedman rank test and Wilcoxon signed rank test are employed to measure the performance of the newly introduced algorithm statistically. The computational complexity has been measured. Moreover, the proposed algorithm has been applied to solve one constrained and one unconstrained real-life problems to examine its problem-solving capability of both type of problems. The comparison results of benchmark functions, statistical analysis, real-world problems confirm that the proposed h-MFOBOA algorithm provides superior results compared to the other conventional optimization algorithms.

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