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Introduction
Andrew Drach currently works at the Institute for Computational Engineering and Sciences, University of Texas at Austin. Andrew does research in Computational Materials Science and Biomedical Engineering.
Current institution
Publications
Publications (51)
Simulations of the biomechanical behavior of the Mitral Valve (MV) based on simplified geometric models are difficult to interpret due to significant intra-patient variations and pathologies in the MV geometry. Thus, it is critical to use a systematic approach to characterization and population-averaging of the patient-specific models. We introduce...
The strength of three-dimensional woven composites is determined by their reinforcement configuration and the strength of their constituents. In the present work, we consider several criteria to predict initiation of damage in matrix of carbon/epoxy composites subjected to uniform temperature drop and uniaxial tension. The matrix is modeled as the...
Consistent growth of the marine aquaculture industry over the past decades calls for potential deployments of large-scale aquaculture structures to produce finfish, shellfish and macroalgae in varying inshore and offshore environments. Numerical simulations for engineering design applications become more challenging with increase of scale since cur...
Floating protective barriers provide essential protection to critical governmental, commercial, and private assets that are vulnerable to water-borne intrusion, such as liquefied natural gas terminals, tankers, etc. These barriers require additional evaluation in the case of their deployment at significant water depth in offshore environments. The...
The AdjustaDepth TechnoEconomic Analysis was prepared by Mark E. Capron PE, Co-PI, under the direction of Kelly Lucas, PhD, PI and submitted April 3, 2019 to U.S. Department of Energy ARPA-E under Phase 1 Contract DE-AR0000916. Its 33 tabs present the cost and yield projections for growing Gracilaria tikvahiae in the Gulf of Mexico. It can be adapt...
Hydrodynamic characteristics are needed to optimize the design of kelp aquaculture systems. To support this need, the objective of this study was to resolve both the normal and tangential drag forces acting on a dense aggregate of kelp blades using full scale physical model tests. The physical model was designed to match the exposed length, individ...
Farmers growing mussels in offshore environments have turned to submerged longline farming as a relatively safe, reliable and profitable way to produce mussels in the exposed ocean environment. However, variations in the environmental conditions (strong currents and storms) and potential presence of predator species (e.g. eider ducks) require robus...
AdjustaDepth Project was funded by the U.S. Department of Energy Advanced Research Projects Agency - Energy to design an artificial reef system for growing and harvesting seaweed for advanced sustainable biofuels. The team discovered that the system grows more seaweed per hectare when it is part of a complete ecosystem with shellfish, finfish, and...
The mitral valve (MV) is the left atrioventricular heart valve that regulates blood flow between the left atrium and left ventricle (LV) during the cardiac cycle. Contrary to the aortic valve, the MV is intimately coupled, fully functional part of the LV. In situations where the MV fails to fully close during systole, the resulting blood regurgitat...
A single kelp longline was designed for an exposed site in the Gulf of Maine. The structural properties of the kelp were taken from prior measurements of fresh samples of Saccharina latissima. Hydrodynamic properties were derived from prior tank tests of a physical model of a 1-m section of a kelp longline with 3-m long kelp fronds. Normal and axia...
The cover image is based on the Research Article A noninvasive method for the determination of in vivo mitral valve leaflet strains by Bruno V. Rego et al., https://doi.org/10.1002/cnm.3142.
Ischemic mitral regurgitation (IMR) is a currently prevalent disease in the US that is projected to become increasingly common as the aging population grows. In recent years, image-based simulations of mitral valve (MV) function have improved significantly, providing new tools to refine IMR treatment. However, clinical implementation of MV simulati...
Assessment of mitral valve (MV) function is important in many diagnostic, prognostic, and surgical planning applications for treatment of MV disease. Yet, to date there are no accepted non‐invasive methods for determination of MV leaflet deformation, which is a critical metric of MV function. In this study, we present a novel, completely non‐invasi...
This study provides an engineering approach for designing an aquaculture cage system for use in constructed channel flow environments. As sustainable aquaculture has grown globally, many novel techniques have been introduced such as those implemented in the global Atlantic salmon industry. The advent of several highly sophisticated analysis softwar...
Velocity vector field of x-z plane.
(MP4)
Velocity magnitude distribution of x-y plane.
(MP4)
Velocity vector field of x-y plane.
(MP4)
Velocity magnitude distribution of x-z plane.
(MP4)
An essential element of cardiac function, the mitral valve (MV) ensures proper directional blood flow between the left heart chambers. Over the past two decades, computational simulations have made marked advancements toward providing powerful predictive tools to better understand valvular function and improve treatments for MV disease. However, ch...
Several stress-based failure criteria (von Mises, dilatational strain energy density, parabolic stress and Drucker-Prager) are implemented in a numerical model of a 3D woven composite to predict initiation of damage due to cooling after curing. It is assumed that the composite is completely cured at elevated temperature and the residual stresses ar...
Ischemic mitral regurgitation (IMR) occurs when a mitral valve (MV) is rendered incompetent by left ventricular (LV) remodeling induced by a myocardial infarction (MI). Hemodynamically significant, IMR affects at least 300,000 Americans. This important clinical problem is expected to grow substantially during the next 20 years as the population age...
For solid specimens, Young's modulus is commonly determined from straightforward uniaxial tension experiments. However, honeycomb specimens are far more challenging to test in tension, and it is therefore desirable to conduct bending experiments to determine Young's modulus. The premise of this work is that the bending response of honeycomb specime...
Multiple studies have demonstrated that the pathological geometries unique to each patient can affect the durability of mitral valve (MV) repairs. While computational modeling of the MV is a promising approach to improve the surgical outcomes, the complex MV geometry precludes use of simplified models. Moreover, the lack of complete in-vivo geometr...
Mitral valve (MV) closure depends upon the proper function of each component of the valve apparatus, which includes the annulus, leaflets, and chordae tendineae (CT). Geometry plays a major role in MV mechanics and thus highly impacts the accuracy of computational models simulating MV function and repair. While the physiological geometry of the lea...
Computational modeling of the mitral valve (MV) has potential applications for determining optimal MV repair techniques and risk of recurrent mitral regurgitation. Two key concerns for informing these models are (1) sensitivity of model performance to the accuracy of the input geometry, and, (2) acquisition of comprehensive data sets against which...
Great potential may exist in the development of abalone aquaculture in underutilized, exposed marine environments. Abalone is a shellfish that feeds on kelp and as a product, can often render high market value. In this study, the development of a commercial-size, submersible abalone cage grow-out system with a modular box structure is described. Th...
In this paper, we present a procedure to develop realistic finite element models of unit cells of 3D woven composites based on the as-woven reinforcement geometry obtained by the textile modeling software. We illustrate our approach by considering a carbon/epoxy woven composite with a layer-to-layer orthogonal reinforcement and describe all steps o...
Statistical modeling is used to correlate geometric parameters of pores with their contributions to the overall Young’s moduli of linearly elastic solids. The statistical model is based on individual pore contribution parameters evaluated by finite element simulations for a small pore subset selected using the design of experiments approach, so the...
Copper alloys are widely used in marine applications because of their very good resistance to corrosion and biofouling. A promising new application is the use of copper alloys as wire material for fishnets in marine aquaculture cages. In this paper, a series of laboratory and field studies to evaluate the suitability of different copper alloys for...
Corrosion fatigue performance of two copper alloys (admiralty brass and cupronickel 90/10) is investigated by conducting fatigue tests in artificial seawater. Two different experimental setups are developed and used: immersed rotating beam bending of round wires and immersed flexural cycling of rectangular plates. For the second setup, two sets of...
Mesoscale modeling of three-dimensional woven composites presents significant challenges related to accurate representation of as-woven geometry of the reinforcement [1]. There are two approaches most commonly used to define the geometry of reinforcement. One is based on the nominal description of composite, and the other one involves fabric mechan...
We use statistical modeling to predict the overall elastic moduli of linearly elastic solids with multiple pores of various shapes. The model is based on the evaluation of contributions from the pore subset selected using the design of experiments approach. It is shown that the accuracy of the model predictions depends on the choice of pore geometr...
Open ocean aquaculture is a rapidly growing industry with the potential to satisfy the global seafood demand in the environment of declining wild fish harvesting. However, technologies developed for inshore aquaculture are not easily transferrable to the exposed fish farm locations. In particular, the structural integrity of fish cage/mooring syste...
It has been well established that aquaculture will supply an increasing share of the world’s seafood demand in the future. Most finfish are raised in marine fish cages consisting of a floating superstructure, polymer net chamber and a sinker weight(s). These systems are susceptible to large deformations, which can lead to reduction of the cage’s vo...
Statistical analysis procedure is proposed to characterize volume, shape and orientation distribution of pores in chemical vapor infiltrated carbon/carbon composites. The microstructure data is provided by X-ray microtomography. To characterize orientation distribution of pores, probability distribution functions of pore volume, orientation angles...
A field testing of corrosion and biofouling behavior of eight copper alloys was carried out at the Portsmouth Harbor, USA (North Atlantic Ocean). The plate specimens of the alloys were submerged for one year to investigate the effect of seawater exposure on corrosion and accumulation of biofouling. The specimens were divided into two sets to evalua...
A low cost monitoring system was designed to provide continuous real-time data on the presence of AC/DC underwater electric currents. The system consists of a PVC support structure with four pseudo-reference electrodes, digital compass and mini PC with high-gain ADC board. The electrodes are arranged as an orthogonal triad: one central electrode is...
A field study on corrosion was conducted on several copper alloys subjected to prolonged exposure in seawater. Rectangular plates made of nine alloys were deployed for a year in the North Atlantic Ocean. Material loss rates were quantified by measuring the difference in weight between the initial virgin specimens and the cleaned specimens after rec...
Copper alloy netting is increasingly used for offshore aquaculture, harbor protection and other marine applications. Its advantageous characteristics include high resistance to biofouling and increased strength compared to polymer nets. However, the hydrodynamic properties of copper nets are not well studied. In this paper, the results of experimen...
Questions
Question (1)
Hi everyone,
As far as I know, the user-defined forces can only be applied to elements (VDLOAD). I could not find in the manual any subroutine to apply user-defined forces to the individual nodes instead of elements. I thought about adapting the VDISP to provide "forces" in the form of incremental displacements/accelerations, but I was hoping that there is some other way to achieve this. On a related note, how about Abaqus Standard?
Thanks!
