Download or read book Study of Mechanical Characteristics of Ankle foot Orthoses Using Finite Element Analysis Method written by Khandhar Previn Chendra Kaushal and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ankle-foot orthoses (AFOs) are external devices applied to the lower leg segment in patients with ankle joint impairment due to neuromusculoskeletal disorders resulting in abnormal gait. In the last three decades, plastic AFOs have superseded conventional metal AFOs. Prescriptions of AFOs by orthotists are usually based on trial and error and if gone wrong, cost time, money and increases the patients' rehabilitation treatment time. This is due to lack of understanding of the mechanical characteristics (i.e. stiffness) and stress distribution of AFOs. There is evidence indicating an optimal match exists between AFOs stiffness and successful rehabilitation. To date, most investigations on AFOs to determine mechanical characteristics are mechanical based. In this investigation an attempt to validate the use of finite element analyses (FEA) in order to predict stiffness and stress distribution of an AFO. Abaqus was used to conduct FEA. The AFO model was subjected to range of loads from 100N to 700N to dorsiflex and plantarflex the AFO. The resulting analysed change in ankle angle, change in length of foot and shank segments, stress distributions were analysed. A linear relationship was found to exist between ankle angle and moment of up to 24.9 Nm and 3.4° during dorsiflexion and moment of 23.9 Nm and 2.7° during plantarflexion and above which, non-linear behaviour is seen. FEA showed asymmetry in buckling displacements at the malleoli in medial and lateral surfaces of the AFO, where the lateral surface was found to be stiffer compared to the medial. However, this result may be inaccurate due to imprecise geometry of the AFO model. High stress concentrations were mainly around the Achilles tendon and malleoli region of the AFO during tension (plantarflexion) and compression (dorsiflexion). It is thought that FEA may be reliable method of studying mechanical characteristics and stress distribution on AFOs but further work is needed to validate the model at its and its accuracy under various conditions of use.
Download or read book A Method of Determining the Characteristics of an Ankle foot Orthosis Using Finite Element Analysis written by Jennifer Cundill and published by . This book was released on 1987 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Determination and Studying of Stress Distribution in Various Ankle foot Orthoses written by Rong Feng and published by . This book was released on 1997 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ankle-Foot Orthosis (AFO) is prescribed to constrain and inhibit abnormal motion such as "drop foot" due to stroke. Most orthoses were hand-made by orthotists according to their own experience. However, some types of AFO were easy to fatigue (out of their functional capabilities) than others due to regular usage. In order to improve the design and usage, quantitative stress analysis of different types of orthoses is needed. The objective of this project is to obtain experimental data which will confirm the results obtained from previous Finite Element Analysis (FEA)[1]. In addition, the experimental analysis is extended to obtain more data related to design parameters in various types of orthoses in order to improve the AFO design. An experimental test system and method are developed which allow accurate measurements of the strain/stress in AFOs. Results obtained from the experimental analysis provided a clear picture of Average Peak Stress (APS) concentration and its distribution. Results further confirmed the hypothesis and results from earlier FEA[1] that peak stress in the orthosis occurs in the neck region. Thus, failure in this place is common and a better design is needed. From the present investigations, the following suggestions are made. Every AFO should be made asymmetrically and the lateral side should be wider or thicker than the medial side.
Download or read book Finite element analysis of ankle foot orthoses written by Mark Andrew Arnold and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Load Analysis of Ankle Foot Orthoses During Gait written by Atichart Kwanyuang and published by . This book was released on 2011 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Different causes of gait deficiencies generate different symptoms. It is important for orthotists to gain a better understanding on how to design Ankle Foot Orthoses (AFOs) in order to address individual biomechanical requirements. The loads acting on AFOs during gait are important factors for orthotists to accurately understand so as to design AFOs more effectively. Therefore, the aim of this study is to develop a validated Finite Element (FE) model, which could be used to quantify and analyse the loads acting on an AFO during gait. In this thesis, for mutual comparison and confirmation, pressures acting on the AFO are recorded by two different types of pressure transducers: resistive and capacitive. Trends of the results obtained from the two sensors are similar; however, the magnitudes tend to be different. Furthermore, an accurate digital 3D scanning model of an AFO is captured using the 3D digitiser which can be modified by Computer Aided Design (CAD) software before being exported to Finite Element Analysis (FEA) software to create an FE model. Both the loads measured from the experiment and the assumed constraint during heel off are then applied to the FE model. To make the analysis more complete, a number of features of AFO and a range of FEA methods are conducted. The results are validated by both empirical findings from previous literature and an additional experiment carried out. Based on a healthy subject with no pathological gait, this study reveals that, on the one hand, the AFO is able to assist walking by carrying 6.89% of the overall magnitude of ground reaction force. On the other hand, it resists walking by generating 18.63% in dorsiflexion of the overall magnitude of the moment generated by the plantarflexors. It is therefore claimed that these findings are useful for orthotists involved in fitting AFOs, in order to efficiently design and construct them.
Download or read book A Method for Measuring the Mechanical Characteristics of Plastic Ankle foot Orthoses written by Edmund Giles William Ward and published by . This book was released on 1987 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Investigation of Bench Methods for Determining Stiffness of Solid Ankle foot Orthoses written by Komaris Dimitrios Sokratis and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The applications of ankle-foot orthoses (AFOs) are nowadays the most common treatment for the compensation of neuromuscular disorders usually caused by stroke and spinal cord or peripheral nerve injuries. The biomechanical functions of plastic AFOs are determined by their thickness, the material selection and their geometry. The geometry, also known as trim-line, reflects the stiffness in relationship to the range of motion that the AFO allows at the talocrural joint (Lin and Bono, 2010). Their design, however, is mainly empirical due to a lack of evidence-based research on their geometrical characteristics (Papi, 2012). Therefore, experimental data are critical for the optimization of AFOs' characteristics. This project aims to investigate the different experimental methods currently utilized for determining the stiffness of homo-polymer and co-polymer polypropylene AFOs with different trim lines. The strengths and weaknesses of each experimental method were analysed and the most reliable techniques has been implemented in order to determine the relationship of AFOs' mechanical properties and their geometry. Three AFOs were tested in total: a 4.6 mm black co-polymer solid AFO, a 6mm homo-polymer solid AFO and a 4.6 co-polymer solid AFO with carbon fibre shape corrugations. The experimental procedure had two objectives: 1. To fabricate and document an effigy leg suitable for the stiffness testing of an AFO. 2. To measure and compare the stiffness of an AFO with/without the presence of the effigy leg by means of different stiffness-measuring methods. The results of this study indicate that the difference in stiffness when a leg is introduced in an AFO is noteworthy while the difference in the results between different methods is considerable as well. It is believed that the cause of this variation is that the manual methods are sensitive to creep and thus the AFO seems to be more flexible when measured manually. The outcome of this study would be beneficial for biomedical engineers and practitioners involved with the manufacturing of custom fabricated AFOs.
Download or read book Design and Simulation of a Single hinge and Adaptive Ankle Foot Orthoses Based on Superelasticity of Shape Memory Alloys written by Morteza Gorzinmataee and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The goal of this thesis is to propose and develop new designs of Ankle Foot Orthosis (AFO) based on superelastic characteristics of shape memory alloys (SMAs). The problem investigated in this research is a human gait abnormality called drop foot caused by the paralysis of the muscles which allow the ankle to dorsiflex. This neuromuscular disorder results in foot slap after heel strike and toe drag during leg swing. As the most common solution, drop foot patients use an orthotic device called AFO add support and improve their gait. However, development of a more compact assistive device, which could passively or actively secure the normal gait requirements, is still a need by both patients and clinicians. Based on investigations and experimentations performed in Dynamic and Smart Systems Laboratory at University of Toledo, SMA is a potential solution due to its unique stiffness behavior and hysteretic characteristics. In this work superelastic characteristics of SMAs is considered as an enabler in the development of new generation of AFOs. Within this work a passive AFO design is proposed which employs a superelastic SMA element as the hinge of the device. This SMA hinge controls the ankle motion by storing and releasing energy during walking. The superelastic element enables the AFO to provide sufficient torque during dorsiflexion to raise the foot in the swing phase of the gait. In order to evaluate the design performance a comprehensive gait analysis study is performed to extract the requirements of motion, understand the critical loads, and calibrate the desired stiffness profiles for the ankle and the superelastic element. A Finite Element Analysis is performed to realize an optimum design for the SMA hinge. Preliminary simulations are carried out in the sagittal plane of the body to verify the functionality of the design in providing the motion requirements. Unlike existing AFOs with two hinges, the proposed design uses only one hinge. The multi-axial loading of the ground reaction in 3D is then simulated to estimate lateral response of the hinge in preventing hypermobility and securing the walking stability. To maintain stability the hinge should limit the motion in directions other than rotation in the sagittal plane. In addition to this passive hinge, superelastic SMA is also envisioned to realize an active AFO. To this end, an active superelastic SMA element which is adjusted structurally and dynamically is used to reproduce the stiffness variation of a healthy ankle. This concept could produce a controlled stiffness profile desired for different walking conditions such as various speeds. Actuation mechanism design for this concept is also discussed. Although, the major contribution of this study is developing a reliable passive AFO design, experimental and numerical analyses confirm the functionality of both passive and active SMA AFOs.
Download or read book Design Enhancement of a Solid Ankle Foot Orthosis written by Khamis Sa'id Abu-Hasaballah and published by . This book was released on 1997 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Full Stride written by Victoria Tepe and published by Springer. This book was released on 2017-09-22 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt: This ground-breaking title begins with an introductory overview of the Lower Extremity Gait Systems (LEGS) project, identifying concerns and observations as context for the reader to consider topics and challenges detailed in later chapters. Next are chapters that explore relevant military and civilian needs, and an essential historical context of the capabilities and limitations of contemporary prosthetics. The section concludes with an overview of essential components used in passive and active lower limb prosthetics, including sockets, foot, ankle, and knee systems, as well as emerging bionic systems. A second section considers research and development in orthotics, synthetic and biological materials, volitional control, and wearable robotics (also known as exoskeletons). Finally, expert authors explore advanced science and emerging medical perspectives in research related to limb salvage, osseointegration, limb transplantation, and tissue engineering. Designed for medical practitioners, engineers, students, and researchers who use or develop prosthetic technology for civilian or military amputees, Full Stride: Advancing the State of the Art in Lower Extremity Gait Systems will be of great interest to trauma specialists, orthopedists, rehabilitation specialists, nursing staff and physical therapists, as well as researchers and scientists who specialize in fields that shape and inform advanced prosthetic device development such as materials sciences, engineering (electrical, mechanical, biomedical), robotics, and human physiology.
Download or read book Emerging Trends and Applications in Artificial Intelligence written by Fausto Pedro García Márquez and published by Springer Nature. This book was released on with total page 611 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Journal of Rehabilitation Research and Development written by and published by . This book was released on 1991 with total page 956 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Investigate the Use of Strain Gauge Technology for the Determination of the Mechanical Characteristics of Polypropylene Ankle foot Orthoses written by Enrica Papi and published by . This book was released on 2008 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Development and Validation of Hybrid Continuum structural Finite Element Model for Evaluating Foot and Ankle Biomechanics written by Saif Alrafeek and published by . This book was released on 2018 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bone is composed of two structures: compact bone and spongy bone. Spongy bone porosity highly affects the strength and the physical endurance of bone to carry loads. Most studies use continuum finite element (FE) approaches to model spongy bone and neglect porosity. Neglecting porosity may not efficiently assist orthopaedic surgeons to treat patients who experience bone physical disability. The purpose of this study is to demonstrate an inexpensive approach that simulates spongy bone with more accurate capturing of porosity and less requirements of bone information. The approach is developed through investigating the mechanical characteristics of spongy bone; that is, by creating and analyzing a structural FE model composed of stochastically oriented structural elements or "beams". Each beam element represents a trabecula. In addition, this study investigates the experimental complex biomechanics of foot and ankle bones loaded in eversion/inversion. Further, this study provides a structural-anatomical description that explains the effect of subtalar joint anatomy and screw constructs on its torsional rigidity.
Download or read book 4th Kuala Lumpur International Conference on Biomedical Engineering 2008 written by Noor Azuan Abu Osman and published by Springer Science & Business Media. This book was released on 2008-07-30 with total page 950 pages. Available in PDF, EPUB and Kindle. Book excerpt: It is with great pleasure that we present to you a collection of over 200 high quality technical papers from more than 10 countries that were presented at the Biomed 2008. The papers cover almost every aspect of Biomedical Engineering, from artificial intelligence to biomechanics, from medical informatics to tissue engineering. They also come from almost all parts of the globe, from America to Europe, from the Middle East to the Asia-Pacific. This set of papers presents to you the current research work being carried out in various disciplines of Biomedical En- neering, including new and innovative researches in emerging areas. As the organizers of Biomed 2008, we are very proud to be able to come-up with this publication. We owe the success to many individuals who worked very hard to achieve this: members of the Technical Committee, the Editors, and the Inter- tional Advisory Committee. We would like to take this opportunity to record our thanks and appreciation to each and every one of them. We are pretty sure that you will find many of the papers illuminating and useful for your own research and study. We hope that you will enjoy yourselves going through them as much as we had enjoyed compiling them into the proceedings. Assoc. Prof. Dr. Noor Azuan Abu Osman Chairperson, Organising Committee, Biomed 2008
Download or read book Dielectric Elastomers as Electromechanical Transducers written by Federico Carpi and published by Elsevier. This book was released on 2011-09-06 with total page 344 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dielectric Elastomers as Electromechanical Transducers provides a comprehensive and updated insight into dielectric elastomers; one of the most promising classes of polymer-based smart materials and technologies. This technology can be used in a very broad range of applications, from robotics and automation to the biomedical field. The need for improved transducer performance has resulted in considerable efforts towards the development of devices relying on materials with intrinsic transduction properties. These materials, often termed as “smart or “intelligent , include improved piezoelectrics and magnetostrictive or shape-memory materials. Emerging electromechanical transduction technologies, based on so-called ElectroActive Polymers (EAP), have gained considerable attention. EAP offer the potential for performance exceeding other smart materials, while retaining the cost and versatility inherent to polymer materials. Within the EAP family, “dielectric elastomers , are of particular interest as they show good overall performance, simplicity of structure and robustness. Dielectric elastomer transducers are rapidly emerging as high-performance “pseudo-muscular actuators, useful for different kinds of tasks. Further, in addition to actuation, dielectric elastomers have also been shown to offer unique possibilities for improved generator and sensing devices. Dielectric elastomer transduction is enabling an enormous range of new applications that were precluded to any other EAP or smart-material technology until recently. This book provides a comprehensive and updated insight into dielectric elastomer transduction, covering all its fundamental aspects. The book deals with transduction principles, basic materials properties, design of efficient device architectures, material and device modelling, along with applications. Concise and comprehensive treatment for practitioners and academics Guides the reader through the latest developments in electroactive-polymer-based technology Designed for ease of use with sections on fundamentals, materials, devices, models and applications
Download or read book A Pilot Study Investigating the Effect of Ankle foot Orthosis AFO Stiffness on Walking Patterns of Patients with Ankle Impairment written by Peeraya Ruthiraphong and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ankle- foot orthoses (AFO) are commonly utilized as one of the standard treatments to improve ambulation in stroke patients. However, AFOs are prescribed and customized to individual patient in a variety of designs by healthcare professionals because there is a lack of strong level of evidence-based studies. In addition, the influence of AFOs' mechanical properties on functional deficit or clinical impairment is still not well understood. Therefore, this study aims to evaluate the biomechanical effects of commonly used AFOs on the lower extremities during the gait cycle. A healthy subject volunteered to be tested walking firstly without an AFO as a control and then wearing a solid carbon fibre reinforced, a solid and two posterior leaf spring AFOs. Strain gauges were attached to each AFO at ankle level to allow the measurement of the moment generated by the orthosis in the sagittal plane. The subject, wearing each instrumented AFO walked in the gait analysis laboratory where kinematic and kinetic data were acquired. This method allows the contribution of the AFOs during walking to be determined, and this information in conjunction with the kinematic and kinetic data, the anatomical moments, which are the moments generated by the muscles and ligaments can be calculated. The results imply that an AFO that is stiffer than the optimal requirement could lead to restriction of ankle motion during the stance phase and have an indirect effect on the knee and hip joints. The findings suggest that the stiffness of AFO, applied in stroke patients should be tailored base on the clinical impairment to get the optimum benefit. It is planned to continue this investigation on stroke patients.
