11 research outputs found
Performance of Rapid Tooling Molds for Thermoformed Sockets
No full textTraditional prosthetic socket fabrication is a laborious and time consuming process that involves physical measurements, plaster wrapping of the stump, plaster casting for positive mold preparation, and a thermoforming process. During the mold preparation stage, significant modifications are performed subjectively based on the prosthetist\u27s experience to transmit an optimum load to the residual limb through the socket. Rapid Prototyping techniques have advanced rapidly during the recent decades emerging as a computer aided socket design alternative which promises a potential reduction in the fabrication time, and a more systematic design approach. In addition, 3-D scanning provides accurate and fast virtual replica of the stump which can be imported in CAD environments. Within 3-D CAD software, prosthetists are able to perform modifications precisely and store files indefinitely. This work examines the potential use of ZCorp 3-D printers to directly manufacture the thermoforming mold required for prosthetic socket manufacture. This work analyses the performance of Rapid Tooling molds for thermoformed socket based on three main parameters: pneumatic permeability, flexural strength and wear rate. The traditional material for mold casting, Plaster of Paris, is compared to materials used for three dimensional printing by Zcorp printers: zp130 and zp140 untreated as well as using them with custom and novel post treatments. To obtain the flexural strength of the different materials, three point bend tests were performed in a universal test machine using ASTM Standard D790-03 requirements. In addition, pneumatic permeability tests were performed to cylindrical specimens of the different materials following ASTM Standard D6539-00. Thermoforming tests confirm that Zcorp 3-D printed parts can serve as effective molds for thermoforming of prosthetic socket
A 3-D Pseudo-Rigid-Body Model for Rectangular Cantilever Beams with an Arbitrary Force End-Load
No full textThis dissertation introduces a novel three-dimensional pseudo-rigid-body model (3-D PRBM) for straight cantilever beams with rectangular cross sections. The model is capable of capturing the behavior of the neutral axis of a beam loaded with an arbitrary force end-load. Numerical integration of a system of differential equations yields approximate displacement and orientation of the beam\u27s neutral axis at the free end, and curvatures of the neutral axis at the fixed end. This data was used to develop the 3-D PRBM which consists of two torsional springs connecting two rigid links for a total of 2 degrees of freedom (DOF). The 3-D PRBM parameters that are comparable with existing 2-D model parameters are characteristic radius factor (mean: γ = 0.8322), bending stiffness coefficient (mean: KΘ = 2.5167) and parametric angle coefficient (mean: cΘ = 1.2501). New parameters are introduced in the model in order to capture the spatial behavior of the deflected beam, including two parametric angle coefficients (means: cΨ = 1.0714; cΦ = 1.0087). The model is verified in a few locations using ANSYSTM and its use in the design of compliant mechanisms is illustrated through spatial compliant versions of crank slider and double slider mechanisms
3D Printed Tooling for Thermoforming of Medical Devices
No full textPurpose: The purpose of this paper is to evaluate the performance of 3D printed materials for use as rapid tooling (RT) molds in low volume thermoforming processes such as in manufacturing custom prosthetics and orthotics. Design/methodology/approach: 3D printed specimens of different materials were produced using the Z-Corp process. The parts were post processed using both standard and alternative methods. Material properties relevant to the 3D printed parts such as pneumatic permeability, flexural strength and wear rate were measured and compared to standard plaster compositions commonly used. Findings: Three-dimensional printing (3DP) can replicate the performance of the plaster materials traditionally used in prosthetic/orthotic applications by using modified post process techniques. The resulting 3D printed molds can still be modified and adjusted using traditional methods. The results show that 3D printed molds are feasible for thermoforming prosthetic and orthotic devices such as prosthetic sockets while providing new flexibility. Originality/value: The proposed method for RT of a mold for prosthetic/orthotic manufacturing provides great flexibility in the manufacturing and fitting process while maintaining proven materials in the final device provided to patients. This flexibility increases the value of digital medical records and efforts to develop model-based approaches to prosthetic/orthotic device design by providing a readily available process for recreating molds. Depending on the needs of the practitioners and patients, 3DP can be incorporated at a variety of points in the manufacturing process
A 3-D Pseudo-Rigid Body Model for Rectangular Cantilever Beams With an Arbitrary Force End-Load
No full textFEM Simulation Methodology for Accurately Capturing the Experimental Vibration Response of ECM Assembly on a Commercial Vehicle
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Optical angular momentum conversion in a nanoslit
No full textWe demonstrate partial conversion of circularly polarized light into orbital angular momentum-carrying vortex light with opposite-handed circular polarization. This conversion is accomplished in a novel manner using the birefringent properties of a circular subwavelength slit in a thin metal film. Our technique can be applied over a very wide range of frequencies and even allows the creation of anisotropic vortices when using a slit without circular symmetry.QN/Quantum NanoscienceApplied Science
L'intelletto nella Risala mahiyyat al-'aql di al-Harith al-Muhasibi
No full textThe epistle on the essence of the intellect places at the center of the research a philological analysis of the term intellect and its conceptual analysis based on the main sources of Islamic knowledge: the Koran and the sunna. The author is also interested in the ethical aspect of the intellect, the ability to distinguish between good and evil. Intelligence, understanding, intellectual light ultimately lead man to the contemplation of divine realities
Effect of the morphology measuring methods of coconut fiber on the determination of mechanical tensile properties
No full textThis study is intended to improve the methodology to calculate the tensile properties of natural coconut fiber and increasing confidence in the use of sustainable natural fibers as reinforcing in composites used for different components in the naval industry. Coconut fiber is an agribusiness by-product that has been shown to have the potential for the development of new materials. The morphology of different species of coconut fiber was studied, and their mechanical tensile properties were determined. The coconut fibers were tested under direct tension in a universal testing machine, and the cross-sectional area of the fibers was calculated using images obtained in an optical microscope and a scanning electron microscope. The study assessed the incidence of key factors to determine coconut fiber mechanical tensile properties including different area measuring methods and the percentage of lumens present through an image analysis software called ImageJ. The results indicate that coconut fiber has a round-shaped cross-section, and the percentage of lumens is between 15% and 27%. Therefore, the effective area is reduced increasing the fiber’s ultimate resistance to tension.这项研究旨在改进计算天然椰子纤维拉伸性能的方法, 并增加使用可持续天然纤维作为增强材料用于海军工业不同组件的信心. 椰子纤维是农业综合企业的副产品, 已被证明具有开发新材料的潜力. 研究了不同种类椰子纤维的形态, 测定了椰子纤维的机械拉伸性能. 椰子纤维在万能试验机上进行直接拉伸试验, 并使用光学显微镜和扫描电子显微镜获得的图像计算纤维的横截面积. 该研究评估了确定椰子纤维机械拉伸性能的关键因素的发生率, 包括不同的面积测量方法, 以及通过名为 的图像分析软件显示的管腔百分比. 结果表明, 椰子纤维的横截面呈圆形, 管腔百分比在15%到27%之间. 因此, 有效面积减小, 增加了纤维的极限抗张力
A subwavelength slit as a quarter-wave retarder
No full textWe have experimentally studied the polarization-dependent transmission properties of a nanoslit in a gold film as a function of its width. The slit exhibits strong birefringence and dichroism. We find, surprisingly, that the transmission of the polarization parallel to the slit only disappears when the slit is much narrower than half a wavelength, while the transmission of the perpendicular component is reduced by the excitation of surface plasmons. We exploit the slit’s dichroism and birefringence to realize a quarter-wave retarder.QN/Quantum NanoscienceApplied Science
