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Abstract: Traditional prosthetic liners are often limited in customization due to constraints in manufacturing processes and materials. Typically made from non-compressible elastomers, these liners can cause discomfort through uneven contact pressures and inadequate adaptation to the complex shape of the residual limb. This study explores the development of bioinspired cellular metamaterial prosthetic liners, designed using additive manufacturing techniques to improve comfort by reducing contact pressure and redistributing deformation at the limb–prosthesis interface. The gyroid unit cell was selected due to its favorable isotropic properties, ease of manufacturing, and ability to distribute loads efficiently. Following the initial unit cell identification analysis, the results from the uniaxial compression test on the metamaterial cellular samples were used to develop a multilinear material model, approximating the response of the metamaterial structure. Finite Element Analysis (FEA) using a previously developed generic limb–liner–socket model was employed to simulate and compare the biomechanical behavior of these novel liners against conventional silicone liners, focusing on key parameters such as peak contact pressure and liner deformation during donning, heel strike, and the push-off phase of the gait cycle. The results showed that while silicone liners provide good overall contact pressure reduction, cellular liners offer superior customization and performance optimization. The soft cellular liner significantly reduced peak contact pressure during donning compared to silicone liners but exhibited higher deformation, making it more suitable for sedentary individuals. In contrast, medium and hard cellular liners outperformed silicone liners for active individuals by reducing both contact pressure and deformation during dynamic gait phases, thereby enhancing stability. Specifically, a medium-density liner (10% infill) balanced contact pressure reduction with low deformation, offering a balance of comfort and stability. The hard cellular liner, ideal for high-impact activities, provided superior shape retention and support with lower liner deformation and comparable contact pressures to silicone liners. The results show that customizable stiffness in cellular metamaterial liners enables personalized design to address individual needs, whether focusing on comfort, stability, or both. These findings suggest that 3D-printed metamaterial liners could be a promising alternative to traditional prosthetic materials, warranting further research and clinical validation
Keywords: bioinspired design, metamaterial model, cellular structure, additive manufacturing, lower-limb prosthetic, 3D printing, finite element method
Published in DKUM: 19.09.2024; Views: 0; Downloads: 1
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Abstract: This article proposes a methodology for the design of double-sided coreless axial flux permanent magnet synchronous machines, which is based on a developed model for calculating the axial component of the magnetic flux density in the middle of the distance between opposite permanent magnets, which also represents the middle of the stator. Values for different geometric parameters represent the input data for the mathematical model in explicit form. The input data are calculated by using a simplified finite element method (FEM), which means that calculations of simplified 3D models are performed. The simplified model consists of two rotor disks with surfacemounted permanent magnets and air between them, instead of stator windings. Such a simplification is possible due to similar values of permeability of the air and copper. For each simplified model of the machine the axial component of the magnetic flux density is analyzed along a line passing through the center of opposite permanent magnets and both rotor disks. Values at the middle of the distance between the opposite permanent magnets are the lowest and are therefore selected for the input data at different stator, rotor disks and permanent magnets (PM) thicknesses. Such input data enable the model to consider the nonlinearity of materials.
Keywords: axial flux, analysis, coreless, development, design, explicit form, finite element method, mathematical models, permanent magnet, synchronous
Published in DKUM: 01.12.2023; Views: 498; Downloads: 19
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Abstract: This paper studies the compliance of the fixture-workpiece system. Workpiece clamping case with two types of clamping elements is considered. The first type of clamping element is standard, with flat top, while the second one is specially designed, with round cutting insert. Analyzed was the case of workpiece clamping using small forces, whereby the deformations in the workpiece/clamping element interface are predominantly on the order of magnitude of roughness height. A comparative analysis of dynamic behaviour of both types of clamping elements is also presented. In comparison with its standard counterpart, the specially designed clamping element with round cutting insert has superior clamping performance regarding both tangential load capacity and compliance.
Keywords: clamping, clamping element design, product development, machining, cutting, compliance, fixture, roughness, analysis, dinamical behaviour
Published in DKUM: 11.07.2017; Views: 1193; Downloads: 104
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Abstract: This paper presents an approach to parameterization based shape optimization of statically loaded elastic structures. The shape parameterization is based on the design element technique and a rational Bezicr body is used to serve as the design element. Practical implementation issues related to the introduction of design variables are discussed briefly. The design sensitivity calculation is based on the discrete approach. The proposed solution process layout is based on a stand-alone optimization program which makes use of compatiblc analysis programs called simulators. For illustrationpurpose an example problem containing shape and sizing design variables is formulated and solved. The range of use of the proposed approachis illustrated with three further examples.
Keywords: mechanics, structure parameterization, shape optimal design, finite element mesh, body parameterization, design element, Bezier body
Published in DKUM: 01.06.2012; Views: 2028; Downloads: 75
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