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California Polytechnic State University, San Luis Obispo

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Articles 91 - 103 of 103

Full-Text Articles in Biomechanical Engineering

Predicting Articular Cartilage Constituent Material Properties Following In Vitro Growth Using A Proteoglycan-Collagen Mixture Model, Michael Stender Mar 2011

Predicting Articular Cartilage Constituent Material Properties Following In Vitro Growth Using A Proteoglycan-Collagen Mixture Model, Michael Stender

Master's Theses

      A polyconvex continuum-level  proteoglycan Cauchy stress function was developed based on the continuum electromechanical Poisson-Boltzmann unit cell model for proteoglycan interactions. The resulting proteoglycan model was combined with a novel collagen fibril model and a ground substance matrix material to create a polyconvex constitutive finite element model of articular cartilage. The true collagen fibril modulus , and the ground substance matrix shear modulus , were varied to obtain the best fit to experimental tension, confined compression, and unconfined compression data for native explants and explants cultured in insulin-like growth factor-1 (IGF-1) and transforming growth factor-β1 (TGF-β1).  Results indicate …


Low-Cost Prosthetic Leg For The Vida Nueva Prosthesis Clinic, Sarah M. Baker, Justin G. Lekos, Jen Van Donk, Kevin Yamauchi Jan 2011

Low-Cost Prosthetic Leg For The Vida Nueva Prosthesis Clinic, Sarah M. Baker, Justin G. Lekos, Jen Van Donk, Kevin Yamauchi

Mechanical Engineering

The Piernas de Vida team partnered with the Vida Nueva Clinic of Prostheses and Orthoses in Choluteca, Honduras to design, plan, and implement a prosthetic foot that could be manufactured entirely by the technicians at the clinic in order to reduce their costs and ultimately allow them to serve more patients each year. Currently, the clinic uses a prefabricated prosthetic lower limb provided by the International Committee of the Red Cross (ICRC) which can be adapted to both transDfemoral and transDtibial patients. The team has successfully developed a foot, currently called the Layer Foot, which can be used by the …


Strider, Eric Johnson, Alex Trask, Ricardo Garcia Jun 2010

Strider, Eric Johnson, Alex Trask, Ricardo Garcia

Mechanical Engineering

No abstract provided.


Medtronic Universal Crimping Machine, Justin Ginochio, Andrew Hanson, Zachary (Zach) Dieterle Jun 2010

Medtronic Universal Crimping Machine, Justin Ginochio, Andrew Hanson, Zachary (Zach) Dieterle

Mechanical Engineering

This project is geared towards the redesign and implementation of a crimping tool for use in the manufacturing of catheters produced by Medtronic Inc. Catheters require two steering cables to maneuver the end of the catheter through the body. The steering cables have a sleeve that is crimped onto their end in order to hold the cable in place inside the catheter steering handle. The current crimping tool, designed by Astro Tool Corp, has a few problems associated with its design. Additionally we are trying to get rid of a step in the manufacturing process that involves the adhesive, cyanoacrylate, …


Edwards Lifesciences: Heart Valve Tension Validation, Lucas Fochler, Alex Mark, Shilpan Shah Jun 2010

Edwards Lifesciences: Heart Valve Tension Validation, Lucas Fochler, Alex Mark, Shilpan Shah

Mechanical Engineering

No abstract provided.


An Investigation Of Humeral Stress Fractures In Racing Thoroughbreds Using A 3d Finite Element Model In Conjunction With A Bone Remodeling Algorithm, Ryan James Moore Feb 2010

An Investigation Of Humeral Stress Fractures In Racing Thoroughbreds Using A 3d Finite Element Model In Conjunction With A Bone Remodeling Algorithm, Ryan James Moore

Master's Theses

The humerus of a racing horse Thoroughbred is highly susceptible to stress fractures at a characteristic location as a result of cyclic loading. The propensity of a Thoroughbred to exhibit humeral fracture has made equines useful models in the epidemiology of stress fractures. In this study, a racing Thoroughbred humerus was simulated during training using a 3D finite element model in conjunction with a bone remodeling algorithm. Nine muscle forces and two contact forces were applied to the 3-dimensional finite element model, which contains four separate load cases representing fore-stance, mid-stance, aft-stance, and standing. Four different training programs were incorporated …


Mechanical Simulation Of Articular Cartilage Based On Experimental Results, Kevin Matthew Stewart Jun 2009

Mechanical Simulation Of Articular Cartilage Based On Experimental Results, Kevin Matthew Stewart

Master's Theses

Recently, a constituent based cartilage growth finite element model (CGFEM) was developed in order to predict articular cartilage (AC) biomechanical properties before and after growth. Previous research has noted limitations in the CGFEM such as model convergence with growth periods greater than 12 days. The main aims of this work were to address these limitations through (1) implementation of an exact material Jacobian matrix definition using the Jaumann-Kirchhoff (J-K) method and (2) quantification of elastic material parameters based upon research findings of the Cal Poly Cartilage Biomechanics Group (CPGBG). The J-K method was successfully implemented into the CGFEM and exceeded …


Simulating The Growth Of Articular Cartilage Explants In A Permeation Bioreactor To Aid In Experimental Protocol Design, Timothy P. Ficklin, Andrew Davol, Stephen M. Klisch Apr 2009

Simulating The Growth Of Articular Cartilage Explants In A Permeation Bioreactor To Aid In Experimental Protocol Design, Timothy P. Ficklin, Andrew Davol, Stephen M. Klisch

Mechanical Engineering

Recently a cartilage growth finite element model (CGFEM) was developed to solve nonhomogeneous and time-dependent growth boundary-value problems (Davol et al., 2008, “A Nonlinear Finite Element Model of Cartilage Growth,” Biomech. Model. Mechanobiol., 7, pp. 295–307). The CGFEM allows distinct stress constitutive equations and growth laws for the major components of the solid matrix, collagens and proteoglycans. The objective of the current work was to simulate in vitro growth of articular cartilage explants in a steady-state permeation bioreactor in order to obtain results that aid experimental design. The steady-state permeation protocol induces different types of mechanical stimuli. When the specimen …


A Cartilage Growth Mixture Model With Collagen Remodeling: Validation Protocols, Stephen M. Klisch, Anna Asanbaeva, Sevan R. Oungoulian, Koichi Masuda, Eugene J.-Ma. Thonar, Andrew Davol, Robert L. Sah Jun 2008

A Cartilage Growth Mixture Model With Collagen Remodeling: Validation Protocols, Stephen M. Klisch, Anna Asanbaeva, Sevan R. Oungoulian, Koichi Masuda, Eugene J.-Ma. Thonar, Andrew Davol, Robert L. Sah

Mechanical Engineering

A cartilage growth mixture (CGM) model is proposed to address limitations of a model used in a previous study. New stress constitutive equations for the solid matrix are derived and collagen (COL) remodeling is incorporated into the CGM model by allowing the intrinsic COL material constants to evolve during growth. An analytical validation protocol based on experimental data from a recent in vitro growth study is developed. Available data included measurements of tissue volume, biochemical composition, and tensile modulus for bovine calf articular cartilage (AC) explants harvested at three depths and incubated for 13 days in 20% fetal borine serum …


Articular Cartilage Tensile Integrity: Modulation By Matrix Depletion Is Maturation-Dependent, Anna Asanbaeva, Johnny Tam, Barbara L. Schumacher, Stephen M. Klisch, Koichi Masuda, Robert L. Sah Jun 2008

Articular Cartilage Tensile Integrity: Modulation By Matrix Depletion Is Maturation-Dependent, Anna Asanbaeva, Johnny Tam, Barbara L. Schumacher, Stephen M. Klisch, Koichi Masuda, Robert L. Sah

Mechanical Engineering

Articular cartilage function depends on the molecular composition and structure of its extracellular matrix (ECM). The collagen network (CN) provides cartilage with tensile integrity, but must also remodel during growth. Such remodeling may depend on matrix molecules interacting with the CN to modulate the tensile behavior of cartilage. The objective of this study was to determine the effects of increasingly selective matrix depletion on tensile properties of immature and mature articular cartilage, and thereby establish a framework for identifying molecules involved in CN remodeling. Depletion of immature cartilage with guanidine, chondroitinase ABC, chondroitinase AC, and Streptomyces hyaluronidase markedly increased tensile …


A Growth Mixture Theory For Cartilage With Application To Growth-Related Experiments On Cartilage Explants, Stephen M. Klisch, Silvia S. Chen, Robert L. Sah, Anne Hoger Apr 2003

A Growth Mixture Theory For Cartilage With Application To Growth-Related Experiments On Cartilage Explants, Stephen M. Klisch, Silvia S. Chen, Robert L. Sah, Anne Hoger

Mechanical Engineering

In this paper, we present a growth mixture model for cartilage. The main features of this model are illustrated in a simple equilibrium boundary-value problem that is chosen to illustrate how a mechanical theory of cartilage growth may be applied to growth-related experiments on cartilage explants. The cartilage growth mixture model describes the independent growth of the proteoglycan and collagen constituents due to volumetric mass deposition, which leads to the remodeling of the composition and the mechanical properties of the solid matrix. The model developed here also describes how the material constants of the collagen constituent depend on a scalar …


A Growth Mixture Theory For Cartilage, Stephen M. Klisch, Robert L. Sah, Anne Hoger Nov 2000

A Growth Mixture Theory For Cartilage, Stephen M. Klisch, Robert L. Sah, Anne Hoger

Mechanical Engineering

In this paper we present a model of growth for cartilaginous tissues in which there exists a saturated solid matrix composed of multiple constituents that may grow and remodel independently of each other. Klisch and Hoger recently developed a general theory of volumetric growth for a mixture of ν-1 growing elastic materials and an inviscid fluid, which included a treatment of two special types of internal constraints that are relevant to cartilage. Here, that theory is specialized to construct a cartilage growth model. This theory allows the constituents of the solid matrix to grow independently of each other, and can …


A Special Theory Of Biphasic Mixtures And Experimental Results For Human Annulus Fibrosus Tested In Confined Compression, Stephen M. Klisch, Jeffrey C. Lotz Apr 2000

A Special Theory Of Biphasic Mixtures And Experimental Results For Human Annulus Fibrosus Tested In Confined Compression, Stephen M. Klisch, Jeffrey C. Lotz

Mechanical Engineering

A finite deformation mixture theory is used to quantify the mechanical properties of the annulus fibrosus using experimental data obtained from a confined compression protocol. Certain constitutive assumptions are introduced to derive a special mixture of an elastic solid and an inviscid fluid, and the constraint of intrinsic incompressibility is introduced in a manner that is consistent with results obtained for the special theory. Thirty-two annulus fibrosus specimens oriented in axial (n = 16) and radial (n = 16) directions were obtained from the middle-lateral portion of intact intervertebral discs from human lumbar spines and tested in a stress-relaxation protocol. …