Papers by Jordan Kelleher
Piston with insulating air gap formed by additive manufacturing
OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Oct 19, 2021
Flow-structure interaction in phonation – The role of vocal fold tissue
Vocal folds are functionally graded tissue structures
Multiphysics and multiscale simulation of phonation: Analysing the effects of smoking on phonation
An Applications-Oriented Measurement System Analysis of 3D Digital Image Correlation
Conference Proceedings of the Society for Experimental Mechanics Series, 2016
The purpose of this paper is to document a measurement system analysis (MSA) for a stereo digital... more The purpose of this paper is to document a measurement system analysis (MSA) for a stereo digital image correlation (DIC) system such that ISO 9001 specifications are met. Many of the prior uncertainty or error studies on DIC have focused on the numerical calculations alone or only specific stages of the metrological process. Thus, there is a need to conduct an MSA to understand the various sources of uncertainty introduced over the entire process and their individual contributions on the final results. The focus of the present MSA was for the practicing engineer in an industrial environment/laboratory. Therefore, the primary sources of uncertainty investigated in this study were the common adjustable parameters that are available to the end user during the system setup and operation. The interdependence of all the factors, both controllable and concealed, elucidated in the literature is acknowledged and conveyed. The measurand of interest was displacement and the particular software utilized to compute the displacements was Vic-3D™ (version 2012) from Correlated Solutions, Inc. The procedure outlined in ISO 98-3 “Guide to the expression of uncertainty in measurement” (GUM) was followed.
Connecting Rod FEA Validation Using Digital Image Correlation
Conference Proceedings of the Society for Experimental Mechanics Series, 2016
Standard structural analyses were performed on a connecting rod in order to assess its durability... more Standard structural analyses were performed on a connecting rod in order to assess its durability. The finite element (FE) model predicted a significant amount of ovalization at the crankpin (i.e. big) end of the connecting rod when subjected to high tensile loads. This ovalization imposed a large bending moment on the crankpin end cap screws. Accounting for the cap screw’s axial preload and the bending moment, the combined stress state was very near the yield strength of the cap screw. It was desired to experimentally validate the FE model. Therefore, an axial tension test was conducted on a sample connecting rod and the deformation near the cap screws was measured using digital image correlation (DIC). Both the axial and lateral deformations between the analytical and experimental data were very well matched. The results of this investigation showed that with good modeling and experimental methods, DIC can be an effective method for model validation.
Biomechanical influences on the vibration of human vocal fold tissue
This investigation attempts to shed light on phonation from a solid mechanics (i.e. biomechanics)... more This investigation attempts to shed light on phonation from a solid mechanics (i.e. biomechanics) perspective. The global hypothesis is that the biomechanical properties of the vocal fold lamina propria are critical to understanding phonatory mechanisms. The contributions of this research can be summarized into two main categories: (1) using optical measurements of vocal fold tensile deformation to determine spatial heterogeneities in the biomechanical properties and the implications of said heterogeneities to phonation, and (2) measuring the vocal fold biomechanical anisotropy and subsequently exploring the effects of the anisotropy on vocal fold vibration through models (computational and analytical). The biomechanical properties were examined using in vitro experiments of human vocal fold cover and vocal ligament specimens isolated from excised larynges. In one study, an improved uniaxial testing protocol was used involving optical measurements of the actual tissue deformation (not simply the applied displacement). The initial longitudinal elastic modulus was found to be considerably higher if determined based on optical displacement measurements than typical values reported in the literature. Also, digital image correlation (DIC) was used to obtain the entire spatial deformation field for a ligament specimen. DIC results revealed that the elastic modulus was very heterogeneous, being approximately 10 times higher at the mid-point of the vocal ligament than in the anterior and posterior macula flavae regions. However, it was discovered that the modulus heterogeneity was much greater in specimens from non-smokers as opposed to those from smokers. Additionally, microstructural images revealed that the collagen fibers were less aligned and less dense at the mid-membranous location in smokers than in non-smokers, which may support the biomechanical heterogeneity findings. The strong modulus gradient is proposed to have a functional role of enabling more complete glottal close which was verified through a finite element eigenmode analysis. A new protocol was developed to enable empirical measurements of the biomechanical anisotropy (i.e. longitudinal elastic modulus to longitudinal shear modulus ratio) within a single specimen by conducting uniaxial tensile and transverse indentation experiments. In the unstretched state, the anisotropy was discovered to be substantially impact the vibration characteristics through transversely isotropic finite element models and analytical Timoshenko beam models. Finally, the anisotropy was represented in a microstructural, anisotropic, nonlinear, hyperelastic constitutive model (Gasser-Ogden-Holzapfel model). Multiphoton microscopy images of a vocal ligament specimen\u27s micro-architecture were analyzed and the degree of collagen fiber dispersion was quantified. The natural frequencies of vibration were predicted using Euler-Bernoulli and Timoshenko beam models in dependence of the neuromuscular elongation of the ligament. The primary factor influencing the natural frequencies as the anisotropy increased was transverse shear deformation
Journal of Biomechanics, 2015
New studies show that the elastic properties of the vocal folds (VFs) vary locally. In particular... more New studies show that the elastic properties of the vocal folds (VFs) vary locally. In particular strong gradients exist in the distribution of elastic modulus along the length of the VF ligament, which is an important load-bearing constituent of the VF tissue. There is further evidence that changes in VF health are associated with alterations in modulus gradients. The role of VF modulus gradation on VF vibration and phonation remains unexplored. In this study the magnitude of the gradient in VF elastic modulus is varied, and sophisticated computational simulations are performed of the self-oscillation of three-dimensional VFs with realistic modeling of airflow physical properties. Results highlight that phonation frequency, characteristic modes of deformation and phase differences, glottal airflow rate, spectral-width of vocal output, and glottal jet dynamics are dependent on the magnitude of VF elastic modulus gradation. The results advance the understanding of how VF functional gradation can lead to perceptible changes in speech quality.
The Laryngoscope, 2014
This investigation quantitatively characterizes the collagenous microstructure of human vocal lig... more This investigation quantitatively characterizes the collagenous microstructure of human vocal ligament specimens excised postmortem from nonsmokers and smokers. Retrospective cohort study. Second harmonic generation (SHG) imaging was performed at three anatomical locations of vocal ligament specimens: anterior, mid-membranous, and posterior regions. Two microstructural parameters were extracted from the SHG images: (1) normalized fiber density, and (2) fiber dispersion coefficient, quantifying the degree of collagen fiber dispersion about a preferred direction. For both the nonsmoker and smoker subjects, the fiber dispersion coefficient was heterogeneous. Differences in the collagenous structure of nonsmokers and smoker subjects were pronounced at the mid-membranous location. However, the directionality of the heterogeneity in the smoker subjects was opposite to that in the nonsmoker subjects. Specifically, the fiber dispersion coefficient in the nonsmoker subjects was lower in the ...
SAE International Journal of Commercial Vehicles, 2014
In recent years, the focus on engine parasitic losses has increased as a result of the efforts to... more In recent years, the focus on engine parasitic losses has increased as a result of the efforts to increase engine efficiency and reduce greenhouse gasses. The engine gear train, used to time the valve system and drive auxiliary loads, contributes to the overall engine parasitic losses. Anti-backlash gears are often used in engine gear trains to reduce gear rattle noise resulting from the torsional excitation of the gear train by the engine output torque. Friction between sliding surfaces at the gear tooth is a major source of power loss in gear trains. The effect of using anti-backlash gears on the gear friction power loss is not well known. As a part of the effort to reduce parasitic losses, the increase in friction power loss in the Cummins ISX 15 gear train due to the anti-backlash gear was quantitatively determined by modifying the methods given in ISO 14179-2 to fit the anti-backlash gear sub-assembly. A test case with a two gear mesh arrangement was designed for the purpose of validating the analysis by rig testing. The torque required to drive the test case as a function of gear rotational speed was measured on the rig. The test plan consisted of two configurations: 1. the anti-backlash gear and a regular spur gear mesh, and 2. the anti-backlash gear replaced by a regular spur gear. An anti-backlash and spur gear from the gear train of the Cummins ISX 15 engine-for the heavy duty market-were used in the rig. Results revealed that the antibacklash gear-regular spur gear mesh required a mean torque of approximately 5 Nm, whereas the regular spur-regular spur gear mesh only required a mean torque of approximately 0.75 Nm. The power losses for these configurations were found to be in good agreement with the analytical results obtained by using the equation for friction losses according to Mauz. The conclusions of this study will impact engineering decisions that must consider the advantages of an antibacklash gear (e.g. reduced gear rattle noise) with its disadvantages (e.g. cost and increased friction).
Progress in Biophysics and Molecular Biology, 2011
Mechanostasis describes a complex and dynamic process where cells maintain equilibrium in respons... more Mechanostasis describes a complex and dynamic process where cells maintain equilibrium in response to mechanical forces. Normal physiological loading modes and magnitudes contribute to cell proliferation, tissue growth, differentiation and development. However, cell responses to abnormal forces include compensatory apoptotic mechanisms that may contribute to the development of tissue disease and pathological conditions. Mechanotransduction mechanisms tightly regulate the cell response through discrete signaling pathways. Here, we provide an overview of links between pro-and anti-apoptotic signaling and mechanotransduction signaling pathways, and identify potential clinical applications for treatments of disease by exploiting mechanically-linked apoptotic pathways.
Journal of the Mechanical Behavior of Biomedical Materials, 2010
The vocal ligament is known to have nonlinear variation in geometry, yet this is rarely considere... more The vocal ligament is known to have nonlinear variation in geometry, yet this is rarely considered in empirical or computational studies. This paper investigates the effects of a nonlinear variation of the anterior-to-posterior geometry and the corresponding spatial variation in elastic modulus on the fundamental frequency of vibration for the vocal ligament. Uniaxial tensile tests were performed on a vocal ligament specimen dissected from an excised 60-year-old male larynx. Digital image correlation (DIC) was used to obtain the spatial deformation field for the entire ligament specimen. DIC results revealed that the tensile deformation was very heterogeneous, with the least amount of deformation occurring in the region of smallest cross sectional area. The elastic modulus was calculated locally and was found to be approximately 10 times higher at the mid-point of the vocal ligament than in the anterior and posterior macula flavae regions. Based on the spatially varying material properties obtained, finite element models (isotropic and transversely isotropic) were created to investigate how the effects of varying cross-section, heterogeneous stiffness, and anisotropy could affect the fundamental frequency of vibration. It was found that the spatial cross-section variation and the spatially varying anisotropy (i.e. modulus ratio) are significant to predictions of the vibration characteristics. Fundamental frequencies predicted with a finite element model are discussed in view of rotatory inertia and contribution of transverse shear deformation.
The Journal of the Acoustical Society of America, 2013
One of the primary mechanisms to vary one's vocal frequency is through vocal fold length chan... more One of the primary mechanisms to vary one's vocal frequency is through vocal fold length changes. As stress and deformation are linked to each other, it is hypothesized that the anisotropy in the biomechanical properties of the vocal fold tissue would affect the phonation characteristics. A biomechanical model of vibrational frequency rise during vocal fold elongation is developed which combines an advanced biomechanical characterization protocol of the vocal fold tissue with continuum beam models. Biomechanical response of the tissue is related to a microstructurally informed, anisotropic, nonlinear hyperelastic constitutive model. A microstructural characteristic (the dispersion of collagen) was represented through a statistical orientation function acquired from a second harmonic generation image of the vocal ligament. Continuum models of vibration were constructed based upon Euler–Bernoulli and Timoshenko beam theories, and applied to the study of the vibration of a vocal li...
Journal of Biomechanics, 2011
In voice research, in vitro tensile stretch experiments of vocal fold tissues are commonly employ... more In voice research, in vitro tensile stretch experiments of vocal fold tissues are commonly employed to determine the tissue biomechanical properties. In the standard stretch-release protocol, tissue deformation is computed from displacements applied to sutures inserted through the thyroid and arytenoid cartilages, with the cartilages assumed to be rigid. Here, a non-contact optical method was employed to determine the actual tissue deformation of vocal fold lamina propria specimens from three excised human larynges in uniaxial tensile tests. Specimen deformation was found to consist not only of deformation of the tissue itself, but also deformation of the cartilages, as well as suture alignment and tightening. Stress-stretch curves of a representative load cycle were characterized by an incompressible Ogden model. The initial longitudinal elastic modulus was found to be considerably higher if determined based on optical displacement measurements than typical values reported in the literature. The present findings could change the understanding of the mechanics underlying vocal fold vibration. Given the high longitudinal elastic modulus the lamina propria appeared to demonstrate a substantial level of anisotropy. Consequently, transverse shear could play a significant role in vocal fold vibration, and fundamental frequencies of phonation should be predicted by beam theories accounting for such effects.
Biomechanics and Modeling in Mechanobiology, 2012
The vocal folds are known to be mechanically anisotropic due to the microstructural arrangement o... more The vocal folds are known to be mechanically anisotropic due to the microstructural arrangement of fibrous proteins such as collagen and elastin in the lamina propria. Even though this has been known for many years, the biomechanical anisotropic properties have rarely been experimentally studied. We propose that an indentation procedure can be used with uniaxial tension in order to obtain an estimate of the biomechanical anisotropy within a single specimen. Experiments were performed on the lamina propria of three male and three female human vocal folds dissected from excised larynges. Two experiments were conducted: each specimen was subjected to cyclic uniaxial tensile loading in the longitudinal (i.e. anterior-posterior) direction, and then to cyclic indentation loading in the transverse (i.e. medial-lateral) direction. The indentation experiment was modeled as contact on a transversely isotropic half-space using the Barnett-Lothe tensors. The longitudinal elastic modulus E L was computed from the tensile test, and the transverse elastic modulus E T and longitudinal shear modulus G L were obtained by inverse analysis of the indentation force-displacement response. It was discovered that the average of E L /E T was 14 for the vocal ligament and 39 for the vocal fold cover specimens. Also, the average of E L /G L , a parameter important for models of phonation, was 28 for the vocal ligament and 54 for the vocal fold cover specimens. These measurements of anisotropy could contribute to more accurate models of fundamental frequency regulation and provide potentially better insights into the mechanics of vocal fold vibration.
Annals of Biomedical Engineering, 2012
The physical mechanisms leading to the acoustic and perceptual qualities of voice are not well un... more The physical mechanisms leading to the acoustic and perceptual qualities of voice are not well understood. This study examines the spatial distribution of biomechanical properties in human vocal folds and explores the consequences of these properties on phonation. Vocal fold lamina propria specimens isolated from nine excised human male larynges were tested in uniaxial tension (six from nonsmokers, three from smokers). An optical method was employed to determine the local stretch, from which the elastic modulus of three segments in the anterior-posterior direction was calculated. Several specimens exhibited a significant heterogeneity in the modulus with the middle segment stiffer than the other segments. It was concluded that such modulus gradients are stronger in specimens from non-smokers than smokers. To understand the functional implications of a modulus gradient, the first eigenmode of vibration was calculated with a finite element model. With a modulus gradient, the vocal fold's eigenmode deflection was spread along the anterior-posterior length, whereas for a homogeneous modulus distribution, the deflection was more focused around the mid-coronal plane. Consequently, the strong modulus gradient may enable more complete glottal closure, which is important for normal phonation, while a more homogeneous modulus may be responsible for poor glottal closure and a perceived ''breathy'' voice.
Piston Cooling Nozzle Oil Jet Evaluation Using CFD and a High Speed Camera
SAE International Journal of Commercial Vehicles, 2016
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Papers by Jordan Kelleher