Hinge Design Research Articles

Design and performance analysis of a composite flexure hinge based on micro-ultrasonic powder molding

This paper presents a new type of flexure hinge and its fabrication method based on micro-ultrasonic powder molding (micro-UPM). A right-circular notch-type flexure hinge (RFR-RC hinge) comprising an aluminum alloy 7075 (Al 7075) rigid structure and a polypropylene (PP) flexible structure was designed and fabricated. This composite RFR-RC hinge was experimentally studied, and the results helped confirm that the hinge could be considered a complete single structure; the flexible structure had a good forming quality, and the interlocking performance met normal use requirements. The RFR-RC hinge was evaluated in terms of its motion range, stiffness, and stiffness ratio through finite element analysis (FEA) and then compared with a single-material right-circular flexure hinge (RC hinge). The RFR-RC hinge provided a significantly wider operation range with a lower actuation force than the Al 7075-RC hinge and a higher motion pureness and accuracy than the PP-RC hinge. The motion stiffness obtained from the FEA was in agreement with the bending test results, thus validating the FEA results to some extent. From the bending tests, the elastic and total motion ranges of the RFR-RC hinge were found to be 0.068 rad and 0.202 rad, respectively. Finally, the fabrication of a 3-RRR compliant parallel mechanism and four typical applications were taken as examples to demonstrate that the RFR-RC hinge and its fabrication method have a wide range of applications.

Survivorship and Functional Outcomes After Complex Primary Total Knee Arthroplasty With Contemporary Rotating-Hinge Implants

Background: Initial fixed-bearing hinge designs for primary total knee arthroplasty (TKA) had high rates of aseptic loosening. There are limited data on contemporary rotating-hinge implants. Purpose: We sought to determine survivorship and functional outcomes of contemporary rotating-hinge implants used in primary TKA. Methods: Retrospective review identified 54 primary rotating-hinge TKAs implanted in 49 patients from 2014 to 2018 at a single institution. Patients identified were 76% women, the mean body mass index was 29 kg/m2, the mean age was 65 years, and the mean follow-up was 3 years. The primary diagnosis for TKA in all cases was severe instability and ligamentous compromise. Secondary diagnoses included post-traumatic osteoarthritis (11, 20%), neurologic disease (10, 19%), inflammatory arthritis (10, 19%), connective tissue disease (3, 6%), valgus deformity (16, 30%), varus deformity (2, 4%), and recurvatum (2, 4%). Preoperative, postoperative (within 6 weeks), and most recent radiographs were reviewed. In this study, we collected preoperative, 1-year, and 2-year patient-reported outcome measures (PROMs) for patients with primary rotating-hinge TKA. Patient-reported outcome measures were prospectively collected, including the Knee Injury and Osteoarthritis Outcome Survey for Joint Replacement (KOOS JR) scores and the Mental (MCS) and Physical Component Scores (PCS) of the Veterans RAND 12-Item Health Survey (VR-12). Kaplan-Meier analysis was used to determine implant survivorship. Results: Reoperation was required in 6% (3/54); indications included periprosthetic joint infection (1), peripatellar fibrosis (1), and periprosthetic femur fracture (1). At both 2 and 5 years, survivorship free from all-cause reoperation was 95% and from revision for aseptic loosening was 100%. Mean KOOS JR scores increased from 47 preoperatively to 65 at 2 years postoperatively. On radiographic review, there were no progressive radiolucent lines consistent with aseptic loosening at final follow-up. Conclusion: The findings of this single-center, multi-surgeon retrospective case series on the use of rotating-hinge implants for primary TKA suggest excellent 2-year survivorship free from reoperation and no revisions for aseptic loosening. We report modest improvement in a variety of PROMs at 1-year and 2-year follow-up. Despite improvement, clinical outcomes were poor for a primary implant. Longer-term follow-up is required to monitor the durability of primary hinges.

Can mechanical heart valves perform similarly to tissue valves? An in vitro study

Current surgical aortic valve (AV) replacement options include bioprosthetic and mechanical heart valves (MHVs), each with inherent limitations. Bioprosthetic valves offer superior hemodynamics but suffer from durability issues, typically initiating deterioration within 7–8 years. MHVs, while durable, necessitate lifelong anticoagulation therapy, presenting risks such as severe bleeding and thromboembolic events. The need for anticoagulants is caused by non-physiological flow through the hinge area during the closed phase and large spikes of regional backflow velocity (RBV) during the closing phase that produces high shear events. This study introduces the iValve, a novel MHV designed to combine the hemodynamic benefits of bioprosthetic valves with the durability of MHVs without requiring anticoagulation. The iValve features eye-like leaflets, a saddle-shaped housing, and an optimized hinge design to enhance blood flow and minimize thrombotic risk. Fabricated using 6061-T6 aluminum and polyether ether ketone (PEEK), twelve iValve iterations were evaluated for their opening and closing dynamics. The reported top-performing prototypes demonstrated competitive performance against industry standards. The proposed iValve prototype exhibited a mean RBV of −4.34 m/s with no spikes in RBV, performing similarly to bioprosthetic valves and significantly outperforming existing MHVs. The iValve’s optimized design showed a 7–10% reduction in closing time and a substantial decrease in RBV spikes, potentially reducing the need for anticoagulation therapy. This study highlights the iValve’s potential to revolutionize prosthetic heart valve technology by offering a durable, hemodynamically superior solution that mitigates the drawbacks of current MHVs.

Outcomes of rotating versus pure hinge knee arthroplasty in the setting of one-stage exchange for periprosthetic joint infection.

Rotating or pure hinge knee prostheses are often used in case of periprosthetic joint infection (PJI). Five-year survival data of rotating hinge implants ranging from 52 to 90%, whereas pure hinge data are sparse. This study describes the results of both hinge knee prostheses after one-stage septic exchange. One hundred sixty-seven one-stage septic exchanges of a primary unconstrained total knee arthroplasty (TKA) to a cemented hinge prosthesis (117 rotating and 50 pure hinge TKAs) performed between 2008 and 2017 were retrospectively reviewed. Exclusion criteria were stem extensions or augments used in primary TKA, history of extensor mechanism reconstruction, and a follow-up less than twoyears after surgery. Rates of reinfection, mechanical failures, and all-cause revision-free survival data were documented. At fiveyears, the all-cause revision-free survival was 77% (95% CI 69 to 82). Thirty-one patients (19%) had further revision for aseptic reasons. In the rotating hinge group, the mechanical failure rate was more than twice as high as in the pure hinge group (13% vs 6%), significantly influenced by higher body weight. At a mean follow-up of 6.7years, 21 (13%) patients had a reinfection and underwent a further surgery. Reinfection rates did not differ between the two groups. The use of hinge TKA in the revision of PJI shows favourable fiveyear infection-free and all-cause revision-free survival rates of 91% and 77%, respectively. Our study showed poorer results of the rotating hinge design. These results may help surgeons to choose proper implants in case of septic knee revision.

Propagation of solitary waves in origami-inspired metamaterials

We propose a design strategy for creating origami-like mechanical metamaterials with diverse non-linear mechanical properties and capable of remote actuation. The proposed triangulated cylindrical origami (TCO)-inspired metamaterials enable the highly desirable strain-softening/hardening and snap-through behaviors via a multi-material and highly deformable hinge design. Moreover, we couple these novel non-linear mechanical properties of the TCO origami-inspired metamaterials with the transformative ability of hard-magnetic active materials, allowing for untethered shape- and property-actuation in the developed metamaterials. We develop a mathematical modeling framework for the proposed TCO origami-inspired metamaterials, building on approximating the highly deformable hinges as a combination of longitudinal and rotational springs. We validate the accuracy of the developed mathematical modeling approach by comparing the analytically predicted compressive response of a unit cell structure with the corresponding numerical and experimental results. Using the developed mathematical modeling framework, we investigate the magnetic field-induced large deformation and superimposed solitary wave propagation in the TCO origami-inspired metamaterial system. We show that the proposed metamaterial allows us to tune the key characteristics of the enabled non-linear solitary waves, including their characteristic width and amplitude. The proposed design strategy for readily manufacturable origami-inspired metamaterial systems paves a novel path for practical engineering applications. Our studies also underscore the potential of magneto-mechanical interaction in the design of reconfigurable metamaterial systems with superior non-linear mechanical and elastic wave properties.

Folding mechanics of a bistable composite tape-spring for flexible mechanical hinge

A bistable composite tape-spring (CTS) structure is stable in both extended and coiled configurations, which can be fully coiled or folded. Its bistable coiling feature has been employed in a Roll-Out Solar Array and successfully deployed in space; its foldable characteristics is analogous to a flexible mechanical hinge, showing great potential to be applied in an aircraft landing gear. Both the structural coiling and folding mechanics are dependent on tape geometry; whilst the correlated scale effect has not been investigated, which significantly constrains its foldable mechanical hinge designs and smart driving analysis in order to further reduce weight and complexity for conventional mechanical hinges. Here, we studied the folding stability mechanics of the CTS structure towards its full tape-length range, where novel stress and shape transitional mechanisms are revealed. This is achieved by investigating the quasi-static folding process of the CTS, where new stable shape features in terms of critical transitional length and stable folded angle are observed and identified through experimental observations, finite element model, as well as theoretical analysis. Theoretical criteria were then determined from the strain energy analysis in comparison to the predefined folded tape shape features. The folding stability mechanisms towards its full tape-length range were proposed in order to facilitate customized flexible hinge design and in-situ smart driving analysis in order to replace conventional mechanical hinges.

Design and analysis of a contact-aided flexure hinge (CAFH) with variable stiffness

This paper presents a novel contact-aided flexure hinge (CAFH) with variable stiffness, which consists of a contact-aided segment, a flexible segment and a rigid part. The proposed CAFH can facilitate a compact design and provide an alternative for stiffness-variable designs under any loading conditions. With a mortise-tenon structure, the CAFH is trivially affected by friction. The design and deformation procedures of the CAFH are described in detail, followed by its theoretical kinetostatic modeling using the chained beam-constraint model. The deformation of all segments is considered in the kinetostatic model, which expands the space of design parameters for stiffness-variable designs. Then, the accuracy of the theoretical model and the variable stiffness design are verified by nonlinear finite element analysis (FEA) and experimental tests. In term of stiffness, the maximum relative errors of the theoretical model are 0.76% in Stage 1 and 0.70% in Stage 2, as compared with FEA, respectively. Further, the parameter sweep is carried out, followed by sensitivity analysis to identify the main test error sources. Finally, the multi-material scenarios are investigated preliminarily, and some outlooks are discussed.

Optimization of DLTS Hinges for the Assembly of the Solar Arrays of a Communication CubeSat

This paper demonstrates the analytical and numerical investigations for the obtainment of the predefined critical parameters of double-layer tape spring (DLTS) hinges. The DLTS hinge is utilized for the coupling between the solar panels to assist the accommodation and formulation of the assumed origami-based pattern of the solar arrays. They are examined for the assurance of safety, durability, non-permanent deformation, and stability from the stowed to the deployment configuration. Von Misses stress (σv) and steady-state moment simulations are investigated by varying the critical hinge design parameters of curvature radius (R), subtended angle (θ) and layer thickness (t). Two optimization models, Taguchi and response surface methodology/RSM, are utilized by employing the computational findings to obtain and validate the modified optimal geometric parameters within this analytical experiment. For the Taguchi method, the optimization of σv and the steady-state moment is accomplished with a t of 1.75–2.25 mm, R of 1.5–2.0 mm, and θ of 1–1.2°. Furthermore, the RSM model shows that the t, R, and θ parameters are determined to be 2.90 mm, 2 mm, and 1.35°, respectively. For optimization of the hinge design, both models should be considered for improved verification and accuracy of the results.

Primary Total Knee Replacement using Rotating Hinge Implants in Poliomyelitis: A Case Series and Review of the Literature.

The results of primary total knee replacement (TKR) using hinge implants performed in the Indian population with post-polio residual paresis (PPRP) are unknown. The purpose of this study was to report the outcome of primary rotating hinge TKR in Indian patients with PPRP at a minimum follow-up of 12 months. We retrospectively reviewed the clinical and radiological records of six patients treated with primary rotating hinge TKR. Pre-and post-operative (at final follow-up) knee range of motion (ROM), knee sagittal deformity, knee society score (KSS), and Oxford knee score (OKS) were compared to determine improvement in function. Six rotating hinge TKRs (five female and one male patient) were analyzed for this study. At a mean follow-up of 27 ± 22 months (range, 12-71 months), the mean pre-operative KSS of 50.6 ± 2.5 significantly improved (P < 0.0001) to 72.5 ± 1.6, and the mean pre-operative OKS of 23.6 ± 1.6 significantly improved (P < 0.0001) to 35.3 ± 1.7. The mean pre-operative knee ROM of 94° ± 10° changed to 92° ± 4° (P = 0.64) and the mean pre-operative sagittal deformity of 7° ± 23.5° changed to -3° ± 2.5° (P = 0.32) at final follow-up. None of the knees had any intra- or post-operative complications or showed radiologic evidence of post-operative loosening, subsidence, or periprosthetic radiolucent lines at the final follow-up. Rotating hinge TKR gave excellent clinical and radiological results at a mean follow-up of 27 months in the present study. Despite TKR being a technically challenging procedure in patients with poliomyelitis-affected limbs, a rotating hinge design, along with meticulous surgical technique, can significantly improve function in such patients.

A New Hinge Prosthesis Offers Ease of Use and the Ability to Retain the Revision Tibial Baseplate.

Total knee arthroplasty (TKA) is a widely practiced surgical procedure, with its efficacy underscored by the increasing number of patients benefiting from it. As primary TKAs rise, the orthopaedic community must prepare for a surge in complex primary and revision knee arthroplasties in the future. While most revisions use non-constrained or semi-constrained prostheses, certain scenarios require a fully constrained (hinge) prosthesis to address major ligamentous and/or bone loss. Over time, hinge designs have evolved, but outcomes with these designs have been mixed. To help address challenges seen with some earlier designs, a new modular revision solution has been designed for both primary and revision surgeries. This system has a new revision baseplate that has compatibilities with varying distal femoral components and introduces an enhanced hinge mechanism. This paper aims to explore the evolution of hinge designs, elaborate on the surgical workflows and intended compatibilities of this new revision hinge system in six different scenarios, and discuss its various potential advantages.

Self-deployable hinges for monolithic space structures using multi-material additive manufacturing

Deployable structures inspired by origami have gained significant prominence in space applications, including solar arrays, reflector arrays, and satellite antennas. Traditionally, these structures consist of separate components that are folded during launch and later deployed in space using springs or actuator mechanisms. However, recent advancements in multi-material additive manufacturing have opened new possibilities for the fabrication of monolithic structures, integrating deployable mechanisms into a single entity. In this paper, we present a novel framework for designing unidirectional (UD) and bidirectional (BD) hinges utilizing viscoelastic materials, incorporated into rigid plates, forming deployable structures. These hinges exhibit the unique ability to store strain energy upon deformation and self-deploy to a flat configuration when released. The experimental results presented here demonstrate the effectiveness and feasibility of our hinge designs in real-world applications. To demonstrate the practical applicability of these hinge designs, we construct a Repeating Unit Cell (RUC) of a large origami-inspired deployable structure, showcasing their compatibility with popular deployable structure patterns.

A Lattice-Hinge-Design-Based Stretchable Textile Microstrip Patch Antenna for Wireless Strain Sensing at 2.45 GHz.

The manuscript presents a novel approach to designing and fabricating a stretchable patch antenna designed for strain sensing and the wireless communication of sensing data at the same time. The challenge lies in combining flexible and stretchable textile materials with different physical morphologies, which can hinder the adhesion among multiple layers when stacked up, resisting the overall stretchability of the antenna. The proposed antenna design overcomes this challenge by incorporating a lattice hinge pattern into the non-stretchable conductive e-textile, transforming it into a stretchable structure. The innovative design includes longitudinal cuts inserted in both the patch and the ground plane of the antenna, allowing it to stretch along in the perpendicular direction. Implementing the lattice hinge pattern over the conductive layers of the proposed patch antenna, in combination with a 2 mm thick Polydimethylsiloxane (PDMS) substrate, achieves a maximum of 25% stretchability compared to its counterpart antenna without a lattice hinge design. The stretchable textile antenna resonates around a frequency of 2.45 GHz and exhibits a linear resonant frequency shift when strained up to 25%. This characteristic makes it suitable for use as a strain sensor. Additionally, the lattice hinge design enhances the conformability and flexibility of the antenna compared to that of a solid patch antenna. The realized antenna gains in the E and H-plane are measured as 2.21 dBi and 2.34 dBi, respectively. Overall, the presented design offers a simple and effective solution for fabricating a stretchable textile patch antenna for normal use or as a sensing element, opening up possibilities for applications in the communication and sensing fields.

Flexure Hinge Design and Optimization for Compact Anthropomorphic Grippers Made via Metal Additive Manufacturing

Abstract Flexure-based grippers offer an attractive alternative to conventional grippers used in robotics and automation. However, most existing designs appear to suffer from insufficient range of motion, loadability, and support stiffness. This article presents an approach to obtain well-performing flexure hinges for compact anthropomorphic grippers made via metal additive manufacturing. We propose a flexure hinge architecture that achieves a high range of motion despite the challenging combination of a small design space, high Young’s modulus, and limited minimum feature size. Furthermore, we present an optimization procedure to generate suitable tendon-driven designs with high loadability. Using this framework, a flexure hinge with an outer diameter of 21.5 mm and range of motion of ±30 deg is synthesized. For the range of 0–30 deg, simulations show a lateral loadability of 52.5–18.6 N and lateral support stiffness of 12,309–11,130 N/m, determined at a gripper interface located 41.2 mm from the hinge pivot axis. Experiments confirm a loadability of at least 15.4 N and determined a stiffness of 8982 to 9727 N/m for same conditions. The results show that the flexure hinge architecture has large potential for a wide range of applications, while in combination with the optimization procedure, superior designs for tendon-driven grippers can be obtained.

Design of a Novel Flexible Spherical Hinge and Its Application in Continuum Robot

Abstract Compliant mechanisms, which can be integrally machined and without assembly, are well suited as joints for continuum robots (CRs), but how to incorporate the advantages of the compliant mechanism into the arm design is a key issue in this work. In this paper, a novel type of flexible spherical-hinged (FSH) joint composed of tetrahedron elements with a fixed virtual remote center of motion (RCM) at the bottom is proposed, and then extended to the CR and end-effector. In the arm design, the error compensation principle is used to offset the parasitic motion of the CR under external load (pressure and torque) and improve the bending and torsional isotropy of the arm through different series combinations, and then the stiffness model of the FSH joint and the statics model of the CR are developed using the 3D chain pseudo-rigid body model (3D-CPRBM) and tested. The results show that the 3D-CPRBM can effectively predict the deformation of the FSH joint and the CR. Moreover, the maximum standard deviation of the bending angle of the FSH joint in each direction is only 0.26 deg, the repeatable positioning accuracy of the CR can reach 0.5 deg, and the end-effector has good gripping ability and self-adaptive capability.

Understanding the force motion trade off of rigid and hinged floating platforms for marine renewables.

In this work, we compare the motion and structural response of a rigid and hinged floating structure subject to regular waves. We do this to understand better whether what is the best option for floating marine renewable installations. The hinged structure has two hinges and three pontoons, whilst the rigid structure is made by replacing the hinges with rigid steel bars. We instrument the pontoons with motion detection spheres and with strain gauges to measure vertical point loads. We find that the motion response of the platforms is similar between hinged and rigid at low and high frequencies. However, at intermediate frequency waves, single and triple sagging occur for rigid and hinged structures, respectively. We find significant load alleviation for the hinged structure in the range of frequencies where sagging behaviour occurs. These insights reveal that hinged design can contribute to long term survivability by reducing loads in the structure, whilst identification of motion patterns and natural frequencies are necessary to select operating modes for marine renewable generators mounted on the platforms.

A comprehensive review on mechanical amplifier structures in piezoelectric energy harvesters

This paper presents a comprehensive review of structural optimization for the piezoelectric energy harvesters by summarizing the characteristics, working principles, advantages, disadvantages, performance, evaluation factors, and potential applications of each amplifier structure. This includes the cantilever, flexure structure, combined structure, multistage structure, and derivative designs such as compound and hinge designs. Examples and optimization method of structural design which utilizes the compressive mode, 33-mode configuration, and stacking design of piezoelectric material is provided. The power output, amplification ratio, and the applied mechanism theory of each structure are then compared and discussed to ease the benchmarking process for future research.

Generalized model and performance analysis of elliptical-fillet cross-sectional flexure hinges

This work presents the design and analytical model of a novel flexure hinge with variable elliptical-fillet cross-section, which can be considered as an extension of existing results on rectangular and/or circular cross-sectional flexure hinges. The closed-form solutions in full degrees of freedom were derived for the compliance, rotational precision, and the maximum von Mises stress under various loads. To validate the analytical model, the theoretical results were compared with finite element analysis based on a set of parabolic notched flexure hinges. Finally, numerical simulations were conducted to evaluate the impact of the cross-sectional geometric parameters on the compliance and stress performance of the flexure hinges. The proposed method casts a unified framework on extended flexure hinges with a cross-sectional shape, which facilitates the systematic optimizations and performance evaluations of flexure hinges in various configurations.

Changes in femoral rollback and rotation with increasing coupling in knee arthroplasty—a biomechanical in-vitro study

BackgroundAfter total knee arthroplasty, 10–30% of patients still complain about knee pain, even after exact positioning of the components. Altered knee kinematics are crucial in this regard.The aim of our study was to experimentally determine the influence of different degrees of component coupling of knee prostheses on joint kinematics during muscle-loaded knee flexion in-vitro.MethodsFemoral rollback and femoral rotation of a standard cruciate retaining (GCR), a posterior stabilized (GPS), a rotational hinge (RSL) and a total hinge (SSL) design of the same series of knee replacement implants (SL-series) of one single manufacturer (Waldemar Link GmbH, Hamburg, Germany) were analyzed and set in relation to the motion of the corresponding native knee in a paired study design. All different coupling degrees were analyzed in the same human knees. To simulate muscle loaded knee flexion, a knee simulator was used. Kinematics were measured with an ultrasonic motion capture system and integrated in a calculated coordinate system via CT-imaging.ResultsThe largest posterior motion on the lateral side was found for the native knee (8.7 ± 7.0 mm), followed by the GPS (3.2 ± 5.1 mm) and GCR (2.8 ± 7.3 mm) implants, while no motion was found for the RSL (0.1 ± 3.0 mm) and the SSL (-0.6 ± 2.7 mm) implants. In contrast, on the medial side, only the native knee showed a posterior motion (2.1 ± 3.2 mm). Regarding femoral external rotation, the only implant where the observed difference did not reach statistical significance when compared to the native knee was the GCR (p = 0.007).ConclusionThe GCR and GPS kinematics closely imitate those of the native joint. Medial femoral rollback is reduced, however, with the joint pivoting around a rotational center located in the medial plateau. Without additional rotational forces, the coupled RSL and SSL prostheses closely resemble each other with no femoral rollback or relevant rotational component. The femoral axis, however, shifts ventrally in both models when compared with their primary counterparts. The positioning of the coupling mechanism in the femoral and tibial component thus can already lead to altered joint kinematics even in prostheses with an identical surface geometry.

Design and analysis of a triangular bi-axial flexure hinge

To achieve the requirement of flexure hinges for specific optical precision equipment, a new triangular bi-axial flexure hinge is proposed. The analysis model for the flexibility of the triangular bi-axial flexure hinges is derived. After that, the linear and nonlinear finite element methods are used to verify the analysis model. Then, the physical dimensions of the hinge are optimized using the multi-island genetic algorithm in conjunction with the finite element method, and the rotational stiffness and center drift are diminished. Static analysis and modal analysis of the hinge are conducted. A test system was built to gage the flexure hinge’s rotational stiffness. The results demonstrated that there was good agreement between the analytically calculated value, simulated calculated value, and experimental value. To summarize, the analysis model met the design requirements of the triangular bi-axial flexible hinge, and the multi-island genetic algorithm effectively optimized the physical dimensions of the hinge and enhanced its performance. The design process provides new ideas for the design of other forms of hinges.

공간형 위치 결정 스테이지를 위한 타원형 및 포물선형 2 자유도 플렉셔 힌지에 대한 해석

With advancements in semiconductor manufacturing processes and the development of precision processing technology, flexure hinge-based ultra-precision positioning stages are widely used. In the flexure hinge, axial and bending stiffness properties greatly influence positioning performance. This study examined the stiffness properties of elliptic and parabolic 2-degrees-of-freedom (DOF) hinges, which have not been extensively discussed. The Timoshenko beam theory was applied to derive the stiffness equations for the axial and bending directions of each hinge. The stiffness properties were examined in several design conditions by comparing theoretical and finite element analyses. Based on the results of the analyses, an empirical formula in exponential form for the design of an elliptic hinge was constructed through surface-fitting. The elliptic hinge was found to be a better alternative to a circular hinge under certain design conditions by adjusting two design parameters. In the future, we will develop sophisticatedly designed hinges with improved axial and bending stiffness properties compared to the existing circular and elliptic hinges.