About
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Introduction
PROFESSIONAL INTEREST AND EXPERTISE
Simulation on Mechanical Engineering, Biomechanics, Motion Analysis, Finite Element Modeling, Mechanical Medical Devices Design. Knowledge on CAD Software and mechanical Design, Programming. High Education Curriculum Design, Academic Leadership, Undergraduate and Graduate Academic Advising. Tutoring, Math.
Additional affiliations
September 2011 - August 2014
Position
- Advisor for Mechanical Engineer Graduate Students
Description
- Review student needs and implement solutions to promote student advancement. Evaluation of curricula, programs and procedures used in different graduate programs.
August 2010 - August 2011
Position
- Invited Scholar
Description
- Collaboration in the research project: Representation of shoulder kinematics during multiplane tasks performed by manual wheelchair users
September 2007 - August 2010
Position
- Advisor for students Industrial Internship
Description
- Serve as liaison between University and industry, to develop joint projects and involve students.
Education
January 1998 - December 2001
September 1992 - May 1994
September 1985 - December 1990
Publications
Publications (85)
The “Virtual Rotor Kit (VRK) Project” is a lightweight and standalone application developed in response to the challenges posed by the COVID-19 outbreak in the field of rotating machinery dynamics. This alternative emulates a rotor test rig, enabling virtual balancing tests on a single-plane rotor and offering students a comprehensive learning expe...
![Figure 2. Backward Design Framework. [11]](profile/Carmen-Muller-Karger/publication/344696252/figure/fig2/AS:947371466821633@1602882367632/Backward-Design-Framework-11_Q320.jpg)
Pacientes venezolanos con amputación transfemoral requieren un dispositivo que facilite la realización de actividades de la vida diaria, esto impulsó el desarrollo de una prótesis policéntrica de rodilla funcional y de bajo costo (Amador, 2014). El dispositivo está sometido a las cargas cíclicas de la marcha humana por lo que es fundamental hacer u...
En este capítulo se muestra el enfoque que hemos adoptado en el Grupo de Biomecánica de la Universidad Simón Bolívar para el desarrollo de dispositivos protésicos y ortésicos, el cual se basa en considerar que si bien existe gran cantidad de productos de este tipo en el mercado internacional, siempre habrá una aproximación que nos permita dar soluc...
The Monte Carlo method is widely used in the field of biomechanics to study the variability of diverse parameters, like tissues properties, magnitude and direction of loads, kinematic of joints, among others. In particular, the failure of bone tissue, which is the target of this investigation, has been extensively studied; however, it is common to...
Polymethyl methacrylate (PMMA) preformed custom implants for cranioplasty applications have two main purposes: to restore the protection normally given by the cranium to the brain, and to improve the appearance of head surface after a traumatism or malformation. These implants have advantage such as material cost decrease, compared with other mater...
Computer Aided Manufacturing (CAM) involve the use of computer programs to drive computerized numerical controlled (CNC) machines, through the creation of detailed instructions (G-code). The aim of this work is to optimize the manufacturing process of the polycentric knee prosthesis using a CAM software. The complexity of some of the pieces that co...
According to a survey done in the literature on the field until 2010, design of 4-bar mechanisms for polycentric knee prostheses was performed heuristically. Therefore, the main motivation of this work was to determine aspects of the design process on this kind of prosthetic devices suitable of a technical approach, which could go far beyond from a...
Many researcher have invested their time in creating mathematical models that simulate the dynamic behavior of hydrodynamic journal bearings. In most of the cases a linear model for constant dynamic coefficient has been used, but recent comparisons between the theoretically and experimentally obtained coefficients have not shown the expected agreem...
Las necesidades de un grupo de pacientes venezolanos con amputación transfemoral orientaron el desarrollo de una prótesis mecánica de rodilla con articulación policéntrica de cuatro barras, la cual fue dimensionada cinemática y estructuralmente, antes de ser manufacturada y posteriormente probada en dos pacientes con amputación unilateral. El objet...
Una prótesis de pie dinámico representa uno de los componentes que conforman el diseño de las prótesis transfemorales y transtibiales, las cuales se han desarrollado para suplir incapacidades físicas debido a la amputación de extremidades inferiores. El presente estudio se enfocó en evaluar la factibilidad de emplear la técnica de inyección asistid...
Se ha desarrollado una herramienta computacional de simulacion para un manipulador de 6 grades de Ubertad La figura del manipulador en pantalla esta constituida por elementos geometricos simples. Utilizando una caracterizaci6n basada en descripciones cinematieas y sistemas de referencia "m6viles". establecidos segUn la convenci6n Denavit-Hartenberg...
RESUMEN El objetivo de este estudio consistió en diseñar un molde de inyección para fabricar un prototipo de prótesis de pie usando herramientas CAD y verificar, mediante un programa CAE, que el diseño propuesto podría generar piezas que pudieran cumplir con su función de forma adecuada de acuerdo a los requerimientos de este tipo de prótesis. Se p...
Resumen. Este trabajo presenta un estudio numérico simulando el comportamiento mecánico de una componente protésica de pie dinámico fabricada de material polimérico por moldeo por inyección. La pieza propuesta, desarrollada en el Grupo de Biomecánica de la Universidad Simón Bolívar (Venezuela), conforma un bloque sólido de aproximadamente 400 cm 3...
Resumen: En la actualidad, se encuentran en el mercado, prótesis fabricadas con una gran variedad de polímeros; esto es debido a las propiedades tan versátiles que los han hecho destacarse frente a otros materiales (metales y madera). Entre estas propiedades se encuentran la facilidad para ser procesados y su bajo costo, además de sus buenas propie...
Para el desarrollo de la prótesis policéntrica de rodilla con mecanismo de cuatro barras se requirió dimensionar el mecanismo considerando su desempeño cinemático, y establecer su comportamiento estructural suponiendo el estado de cargas al cual será sometido. El dispositivo propuesto está conformado por 5 eslabones y 4 ejes y fue analizado estruct...
Injuries of the vertebral column have gradually increased in recent years, this has favored interest in the production of computer models that provide medical solutions and guide in the diagnosis of certain pathologies. One of the challenges that can be found in the development of computational models is the simulation of the behavior of the interv...
The aim of this work is find the proper dimensions, under a structural perspective, of a polycentric prosthetic knee. The proposed 4 bars mechanism, tested successfully for stable kinematic function, is composed by five links (aluminium 7075) and four axes (stainless steel 304). Stress analysis was performed using finite elements method under three...
To develop evidence-based strategies for preserving shoulder function in manual wheelchair (WC) users, approaches for comparing upper extremity 3D kinematics across a variety of activities of daily living require further development. In this study, Euler and quaternion based methods for parameterizing shoulder kinematics were quantified and compare...
The intervertebral disc is composed by three regions: an annulus fibrosus, a nucleus pulposus, and the terminal plates. The annulus fibrosus consist of concentric layers of collagen type I and II with fibers tilted in opposite direction in adjacent layers, the nucleus pulposus is composed of type II collagen and water. This work presents a sensitiv...
A comparative analysis between polymeric materials suggested for a new design of a Dynamic Energy Return (DER) prosthetic foot is presented. This component, developed in the R+D Biomechanics Group of the Universidad Simón Bolívar, conforms a solid block of some 400 cm3, which is unusual in injected plastic parts and requires particular requirements...
The aim of this work is to show the results of the stress analyses performed during the structural design of a polycentric knee prosthesis. This was done by means of the finite element method and three different contact conditions between the assembly parts. The analyses were performed under the most critical load condition defined by the standard...
The intervertebral disc is the structure that lies between adjacent vertebrae in the spine; is composed by an annulus fibrosus and a nucleus pulposus, and work as a shock absorber. The annulus fibrosus consist of concentric layers of collagen type I and II, the nucleus pulposus is composed of type II collagen and water. In biomechanical studies of...
The aim of this work is to show the results of the
stress analyses performed during the structural design of a
polycentric knee prosthesis. This was done by means of the
finite element method and three different contact conditions
between the assembly parts. The analyses were performed
under the most critical load condition defined by the standard...
A gait analysis laboratory is essential for quantifying gait disorders, as well as for designing and assessing prosthetic devices. Such facilities are usually equipped with sophisticated devices; such as optoelectronic motion capture systems and force platforms, which require highly-trained personnel for proper equipment operation and maintenance....
Contrasts are common in developing countries, where on one hand most medical devices are available but costly for most of the population, and on the other there is high-tech in some R+D centers, which could be used to create high quality products with more competitive prices. This paper is aimed as a bridge between these two realities in Venezuela....
El mecanismo policéntrico de una prótesis de rodilla posee un centro instantáneo de rotación (CIR) que varía en función del ángulo de flexión, otorgándole mayor movilidad y estabilidad a la articulación cuando posee las dimensiones adecuadas. En particular, el mecanismo policéntrico de 4 barras involucra 6 parámetros, los cuales fueron dimensionado...
The purpose of this technical paper is to describe the development of a measurement system to assess the biomechanics of independent WC-to-car transfer and lifting of the WC frames of varying dimensions into and out of a car; consisting of a 16-camera motion capture system and 6- DOF force sensor units mounted to the steering wheel, car seat, and o...
This paper presents a physiological model of a L4-L5 Functional Vertebral Unit (FVU) based on dimensions extracted from the literature, which is used as a platform for simulation of Nucleus pulposus prostheses prototypes. CAD computational tools and finite element simulations were used for stress analysis considering the anisotropy of the outer ann...
This research was aimed to develop a methodology for establishing the proper dimensions of a four-bar linkage
prosthetic knee mechanism for maximum stability. Based on the fact that the stability of a four-bar knee during load-bearing is determined by the location of the instantaneous center of rotation (ICR) with respect to the ground reaction for...
Most work done on bone simulation has modeled the tissue as inhomogeneous and isotropic even though it is a recognized anisotropic material. Some recent investigations have included orthotropic behavior in bone finite elements (FE) models; however the problem regarding the orientation of these properties along the irregular bone anatomy remains. In...
El objetivo principal de este trabajo fue el mecanizado de un prototipo de prótesis de pie dinámico sin articulaciones fabricado en material polimérico. El dispositivo busca satisfacer las necesidades de personas con discapacidad dentro del Nivel 2 de Movilidad, de acuerdo al perfil del protocolo de la Agencia del Financiamiento para el Cuidado de...
This research is aimed to establish the conceptual design of a knee prosthesis for transfemoral amputees in Venezuela. A state-of-the-art review was carried out and interviews with users were performed in order to state the design criteria. Taking these into account, the concept of the prosthetis was based on a voluntary control four-bar linkage pr...
There is a very large need for prosthetic components in developing countries, where such devices are imported and prohibitively expensive. This work explores the possibility of developing and manufacturing prosthetic components locally in Venezuela while preserving high quality and function. We aimed at developing a kit
of plastic modular adaptors...
El objetivo principal de este trabajo fue el mecanizado de un prototipo de prótesis de pie dinámico sin articulaciones fabricado en material polimérico. Las prótesis persiguen sustituir una
parte del cuerpo que ha sido perdida por una amputación o que no exista a causa de agenesia, cumpliendo las mismas funciones de la parte faltante. El pie protés...
This study aimed to machining of prototyping dynamic foot prosthesis without joints, made of polymeric material. The prosthesis is aimed at satisfying the needs of people with disabilities within the Mobility Level 2, according to the profile of the protocol of the Health Care Financing Administration (HCFA). The piece was machined into a Center of...
Este estudio tuvo como objetivo principal diseñar un molde de inyección para fabricar un prototipo de prótesis para pie usando herramientas de diseño asistido por computador (CAD, del inglés computer-aided design), y verificar, mediante el método de elemento finito, que el molde propuesto podría generar piezas que pudieran cumplir con su función de...
Existen programas de reconstrucción ósea comerciales que si bien son muy eficientes en el proceso de segmentar imágenes, tienen carencias en los módulos de discretización; además son inasequibles para países en desarrollo. El objetivo de este trabajo es elaborar y comparar modelos de vértebras humanas creando una metodología de reconstrucción ósea,...
There is a very large need for prosthetic components in developing countries, where such devices are imported and prohibitively expensive. The present work explores the possibility
of developing and manufacturing prosthetic components locally in Venezuela, preserving high quality and function. We aimed to develop a kit of plastic modular adaptors f...
Este documento describe los resultados del diseño y construcción de dos prototipos de ortesis de miembro inferior de tipo KAFO termoconformado desarrollados en el Grupo de Biomecánica de la Universidad Simón Bolívar. Las ortesis diseñadas se enfocan en dar respuesta a pacientes con deficiencia muscular, en una o ambas piernas, y que en consecuencia...
Actualmente alrededor del 10% de la población mundial sufre de algún tipo de discapacidad. En Venezuela, alrededor de 60.000 venezolanos poseen alguna discapacidad del miembro inferior. Fuentes no oficiales estiman que, desde el 2001, esta cifra prácticamente se ha duplicado, debido al aumento de los accidentes viales y de la violencia en el país....
The main goal of this project was to design, evaluate and
validate an interbody fusion cage (IFC) and its injection
mold by means of CAE/CAD and finite elements tools
(Pro-ENGINEER, C-MOLD and ANSYS). IFC is
employed as a supplement in the lumbar fusion. PEEK was
chosen for IFC manufacture. Based on the interbody cage
design, two cavities and a dou...
Numerical tests were conducted on a novel design of a Dynamic Energy Return (DER) prosthetic foot. The technology of the proposed prosthetic foot includes a flexible keel capable of storing and liberating energy. In contrast to traditional models, the proposed model does not consider soft components. All absorption and energy return is done by mean...
The influence of the fixation plates on the ostheosynthesis process of the 41-C1 tibia fracture is analysed in this research, by studying the fracture fragments displacements when a compressive load is applied. A cadaveric tibia and a synthetic tibia were experimentally and numerically compared. Then, two different FEM of fractured tibia were devel...
Most of the finite element models found in the literature assumes that the mechanical behavior of the bone tissue is isotropic. In order to produce more accurate models, this study proposes the incorporation of transversally isotropic material properties. An analysis of the model's sensibility to the orientation of the material's properties, using...
The aim of this work is to study the influence of different configurations of boundary conditions in the behavior of finite elements models built to simulate mechanical tests of two front bovine tibias. Computerized tomography was used to reconstruct the geometry and to assign mechanical properties which include the heterogeneity and orthotropy of...
The aim of this work is to study the influence of different configurations of boundary conditions in the behavior of finite elements models built to simulate mechanical tests of two front bovine tibias. Computerized tomography was used to reconstruct the geometry and to assign mechanical properties which include the heterogeneity and orthotropy of...
The goal of this paper is to describe the advances in the design of a simple manufacturing artificial foot. Considering that low cost solutions, to cover the demand of handicap persons, is a necessity in developing countries, the aim of this research is to contribute to solve part of the problem.
The conceptual design of the artificial foot here de...
The proximal tibia fracture 41-C1 is analyzed with and without the use of fixation plates. This analysis is done considering the different stages of the fracture healing callus (soft and mature). The study is built on a finite element model of a synthetic tibia (Synbone®), which assumes linear and isotropic material behavior. It was utilized to bui...
In Venezuela there is an important demand of all kind of external prostheses components, basically due to the
fact that the available ones are imported and hence, too expensive for the people who needs them. Having
consciousness of it, the idea of this project is to produce adaptors of acceptable quality for a low cost, which actually get to the pa...
Most of the bone models used in biomechanical analysis are isotropic. This paper
presents the stress analysis results for an anisotropic model of proximal femur. The
geometrical reconstruction and assignation of heterogeneous mechanical properties was
made using CT data. Anisotropic behavior of bone is considered three-dimensionally,
assuming trans...
In Venezuela there is an important demand of all kind of external prostheses components, basically due to the fact that the available ones are imported and hence, too expensive for the people who needs them. Having consciousness of it, the idea of this project is to produce adaptors of acceptable quality for a low cost, which actually get to the pa...
The development of a prosthetic device for the replacement of the nucleus pulposus of the intervertebral disc is being widely studied in the recent years, with a great variety of designs and materials used. In this work is shown an approach to the elaboration of prosthesis for the nucleus pulposus, following the principal requirements about biomech...
El presente trabajo tuvo como finalidad realizar un modelo tridimensional de una unidad vertebral funcional de la columna lumbar donde se pueda estudiar la mecánica del disco intervertebral, tanto en su estado normal como al ser sustituido por lgún tipo de prótesis, para comparar su comportamiento. A travéws de tomografías axiales computarizadas de...
Bone materials are characterized for being highly heterogeneous and anisotropic, and therefore difficult to simulate through computational models. Computerized Axial Tomographies (CT) are currently used to obtain external geometry and elastic module of bone using the gray scale of CT by means of known experimental power equations. In the literature...
This investigation seeks to achieve a heterogeneous and
anisotropic characterization of bone in a simple form and with
low computational cost. The ultimate purpose is to create a
model and a platform to design and simulate medical devices.
CT is used to develop a geometric reconstruction of the bone,
and to assign the heterogeneous and symmetric me...
A three-dimensional model of the human tibia bone subject to realistic static physiological conditions was developed using the p-version of the finite-element method. The p-version of the finite-element method in combination with the blending-function method enabled the construction of elements displaying accurate representation of the domain's bou...
In this work a three-dimensional model of bone, under physiological conditions, is developed with the purpose of a better understanding of the bone tissue. To accomplish the simulation it is necessary to develop a methodology for the extraction of geometry and material properties from Computerize Axial Tomographies. An ASCII format properties-array...
In this work a three-dimensional model of bone, under physiological conditions, is developed with the purpose of a better understanding of the bone tissue. To accomplish the simulation it is necessary to develop a methodology for the extraction of geometry and material properties from Computerize Axial Tomographies. An ASCII format properties-array...
In this paper, a three-dimensional Boundary Element model of the proximal tibia of the human knee is described and stresses and displacements in the tibial plateau under static loading are computed. The geometry is generated via three-dimensional reconstruction of Computerized Tomographies and Magnetic Resonance Imaging. Various models of different...
The p-version of the finite element method is considered to be a very accurate
discretization method for linear elliptic partial differential equations. In a combination
with the blending function method, which enables to construct elements with an exact
representation of the domain's boundary, complex structures can often be modeled with a
few ele...
En este trabajo se ha desarrollado una herramienta computacional de simulación para un manipulador de 6 grados de libertad, el cual se acopla a un brazo robot real. EL software fué desarrollado en el lenguaje Visual Basic para lograr versatilidad gráfica, y los módulos de cálculo fueron programados en Fortran para mayor rapidez y eficiencia en las...
In this research a computational tool have been developed for the simulation of a 6 degree of freedom manipulator, which is connected with a real robot arm. The Software was developed in Visual Basic to obtain graphic versatility and the calculus modules were developed in Fortran 77 to ensure faster and more efficient mathematical operations. The f...
Se ha desarrollado una herramienta computacional de simulación para un manipulador de 6 grados de libertad. La figura del manipulador en pantalla esta constituida por elementos geométricos simples. Utilizando una caracterización basada en descripciones cinemáticas y sistemas de referencia "móviles". establecidos según la convención Denavit-Hartenbe...
A linear analysis of the parameters for the orbital transient response of journal-bearing systems is made with the purpose of computing the bearing dynamic coefficients using the minimum square method. The journal-bearing response is obtained from a nonlinear simulation that includes a transient solution of the Reynolds equation. The minimum square...
The problem of long beams with combined bending, shearing, elongation and torsion, with large deflexions, has long been avoided because of its complexity for modelling and solving. The transient response of the beams adds other complications. This paper introduces a model for this problem using the analogy of an elastic whip. Whips as slender weigh...
