The Scientific Computation Research Center (SCOREC)
Automated Adaptive Finite Element Modeling Techniques to reliably automate all aspects of finite element analysis over arbitrary 3-D domains are developed. Research topics include automatic 3-D mesh generation, a posteriori error estimation, and multilevel mesh enrichment by h- and hp-methods.(Shephard/Georges/Flaherty)
Unsteady Rotor Aerodynamics This project is concerned with the development of effective numerical analysis techniques to predict global/local failure of multichip interconnects subjected to both thermal and mechanical loads. Specialized variational techniques are used for the global analyses while the local thermal analysis is performed using a floating random wald method and the local thermomechanical analysis by automated adaptive finite element techniques. (Shephard/LeCoz/Sham/Tiersten)
Unsteady Rotor Aerodynamics This project is concerned with the development of automated adaptive finite element techniques to perform compressible flow analyses of 3-D rotorcraft configurations accounting for the large rigid body and coupled elastic deformation of the rotor and its interaction with the airframe.(Shephard/Bauchau/Busak)
Automated Metal Forming Modeling In the development of automated finite element modeling techniques for three dimensional bulk forming simulations, emphasis is placed on the procedure to track the evolution of the domain definition of general 3-D forming problems as the simulation proceeds. (Shephard)
Automated 3-D hp-Meshing for Structural Acoustics This prject is concerned with the development of automatic mech generators to produce optimal hp-meshes for use in acoustics analysis of complex 3-D structures. (Shephard/Georges)
Analysis Idealization Control System Development and implementation of a framework to support the explicit control of analysis idealization steps during the multiple engineering design is the focus of this project. The system supports, in a consistent feedback structure, all levels of idealization based on a posteriori estimation to knowledge-based modeling rules. (Shephard)
Mechanism-Based Modeling of Composite Materials This project is concerned with the development of advanced multiscale analysis and adaptive idealization control techniques to predict the thermo-mechanical behavior of high performance composites accounting for nonlinear materials, damage and local failure. Automated adaptive finite element techniques employing superposition and hp-refinements are being emphasized.(Fish/Shephard)
Composite Material Process Modeling Finite element based techniques to model the diffusion and chemical reactions governing the vapor deposition of matrix materials onto fibers is under consideration and development. (Flaherty/Shephard)
Adaptive Analysis of Soft Hydrated Materials Soft tissure structures can be modeled using bi-phasic equations. The accurate solution of these equations over the complex 3-D configurations common to human joints requires the development of automated adaptive finite element modeling techniques, which is the focus of this projects. (Spilker/Shephard)
Automated Adaptive Analysis on Parallel Computers The number of computations required to solve the complex nonlinear behaviors governing many phenomena of engineering interest is well beyond solution on a uni-processor, even when effective adaptive techniques are used. This project area is concerned with the development of efficient parallel solution techniques for adaptive finite element techniques on general unstructured 3-D meshes (Flahery/Shephard)
Simulation and Control of Fatigue Crack Propagation Modeling Techniques for Stiffened Shells This project is concerned with the development of reliable analytical and numberical tools to predict the structural integrity and residual strength of aircraft fuselage structures with damage in order to determine the safe and economical service life of pressurized fuselage structures. (Fish)
Modeling of Discontinuous Fields Efficient numerical tools to model discontinuities, such as cracks, delamination, shear bands, etc. are being developed. (Fish)
Multiscale Computational Techniques in Laminated Composite Shells Prediction of failure mechanisms in laminated composite shell structures on the macro-scale, critical displacements and stresses, buckling loads, and on the microscale, including microbuckling, microstresses, microcracking, etc. are the major concerns of this project. (Fish)
The s-Version of the Finite Element Method This project focuses on the development of innovative adaptive techniques for solving partial differential equations based on the combination of superposition and multigrid methods. (Fish)
Multiscale Computational Techniques Mulutipurpose computational techniques aimed at hierarchically improving the quality of numerical solutions and mathematical models are being developed. (Fish)
Extraction TechniquesThis project is concerned with the development of postprocessing techniques in extracting engineering data of interest, such as reactions, natural frequencies, stresses and displacements from the basic numerical solution. (Fish/Shephard)
Parallel Automatic Mesh Generation Parallel implementations of our automatic 3-D mesh generations are aimed at producing meshes with over billion elements. (Shephard)
Mechanics of High-Temperature Composites Several projects in this general area are concerned with identification of deformation mechanisms and development of constitutive relations for fibrous and particulate composite matericals made of ceramic, intermetallic, and metal constituents. Of particular interest is the behavior at high-service temperatures where time-dependent deformation may become significant. Response to both monotonic and cyclic loads and to thermal changes is considered.
Modeling of Hot Isostatic Pressing and Thermomechanical Processing Many high-performance composite systems are fabricated by hot isostatic pressing of elemental powders and fibers at elevated temperature. Cooling to room temperature causes dissimilar thermal deformation of the phases and thus creates a residual stress state thate may reduce the load-bearing capacity of the finished product. This research explores modifications of the processing variables to obtain more favorable initial stress states.
Thermomechanical Fatigue of Sic/Ti Systems Titanium matrix composite laminates are considered as candidate materials for advanced aerospace vehicles and propulsion systems. Thermomechanical cyclic loading is of concern as it may lead to fatigue damage and failure. Micromechanical modeling and experimental simulation of the intermal cyclic strain states is conducted to gain understanding of the admissible loading conditions for these systems.
Optimum Design of Submersible Composite Structure Carefully manufactured carbon fiber-epoxy matrix laminates exhibit high compressive strength that is desirable in structures supporting high pressures. Optimized, minimum weight design procedures are being studied for improved performance at reduced cost.
Transformation Field Analysis of Heterogeneous Media and Composite Laminate In addition to extermal load, composite materials and heterogeneous media in general are often loaded by internal deformations that may be caused by thermal changes, phase transformations, moisture absorption, or inelastic deformation. A general method for analysis of these effects has been developed for application to diverse practical problems.
Thermomechanics of Functionally Gradient Materials Composite materials with prescribed distributions of elastic moduli and coefficients of thermal expansion are of interest in applications involving large temperature or stress gradients. Micromechanical modeling of the local gradient fields and overall thermomechanical properties, and design of such systems, are in progrss.
Experimental Characterization of Composite Materials Measurement of overall mechanical properties, such as stiffness, inelastic deformation as a function of loading path and time, and strength, are conducted under axial and biaxial monotonic or cylic loading, on plate and tubular specimens, at temperatures up to 1200 degress C.
Mechanics of Piezoelectric Composites and Active Materials Composite materials made of electroelastic constituent materials exhibit coupled properties. Micromechanical modeling of such systems reveals the intermal structure of the macroscopic constitutive relations that need to be considered in design. Related studies of composites with shape memory alloy constituents are in progress.
Damage Development in Composite Laminates Internal damage states, such as fiber debonding and matrix cracking, can reduce stiffness, open the material to environmental attack, and inhibit strength. Failure maps that indicate the overall stress states leading to onset of damage in ceramic and intermetallic systems are in development.
Earthquake Response of Circular Concrete Water Tanks This project is concerned with reviewing the ACI and AWWA Design Standards for the consideration of earthquake design provisions and updating them to conform to modern code standards. Simplified design provisions are also being developed (Feeser)
Electrified Roadway for Battery Recharging for Electric Highway Vehicles The technical feasibility of using microwave technology for transmitting power fro the road way to electric highway vehicles is being studied. This includes investigation of the power distribution infrastructure needed to move toward electried highways. (Feeser, Grivas, Salon)
Snowloads on Structures This projects focuse on the development of relationships for snow drift loads on multilevel roofs suitable for use in building codes and load standards. (O'Rourke)
Seismic Behavior and Design of Buried Pipelines Relative displacement and rotation at the joints of buried pipelines subject to seismic wave propagation is being determined. Studies include consideration of the variablility of parameters in actual systems and comparison of analytical estimates with observed behavior during the September, 1985, Mexico City earthquake. (O'Rourke)
Prediction of Earthquakes Strong Motion The focus of this project is the analysis and modeling of earthquake strong motion accounting properly for local site effects. The earthquake response of geologic structures such as sedimentary valleys and canyons is studied in a unified treatment with the seismic source. The ultimate objective is the prediction of earthquake strong motion in a form useful for earthquake engineers based on understanding the basic physical laws governing fault mechanics and propagation of waves through realistic media. (Papageorgiou)
National Center for Earthquake Engineering Research (NCEER) A $50 million, 5-year National Center for Earthquake Engineering Research was established in 1986 at SUNY Buffalo as a consortium of several universities, including Renssalear. The Center is supported by the National Science Foundation and the State of New York. The Center was renewed in 1991 for another 5 years, and received additional support from the Federal Highway Administration for research on design and retrofitting of highway structures. This earthquake center is an interdisciplinary effort involving seismologists, geologists, structural and geotechnical engineers, and social scientists. At Rensselaer, the research activity is concentrated in the Civil and Environomental Engineering Department, and includes the following major areas: strong ground motions in soils and alluvial valleys, soil failure, seismic behavior of earth dams, seismic response of buried lifelines, and earthquake geotechnical entrifuge model studies of liquefaction, retaining walls, foundations, and highway bridge structures.
Development of Site Coefficients for Seismic Codes Systematic research is conducted to study local amplification of earthquake rock motions by the soil to develop site categories and site coefficients for building seismic codes. Computer parametric studies cover a wide range of rock and soil conditions, earthquake types and levels of shaking typical of the various U.S. seismic regions. These studies help generalize the existing experience from instrumental records on different ground types during earthquakes such as Mexico City in 1985 and Loma Prieta, California in 1989. The results and proposed code modifications are coordinated with other centers and universities and are presented to various national commitees preparing the new generation of seismic codes. (Dobry/Papageorgiou)
Development of Soil Cyclic Laboratory and New Geotechnical Centrifuge With support from NCEER, NSF, New York State, the Air Force Office of Science Research, and Rensselaer, a plan has been implemented for the rapid modernization and ecpansion of Rensselaer's Class of 1933 Earthquake Engineering and Cyclic Loading Soils Laboratory. This includes acquisition of miscellaneous laboratory and computer equipment to enhance the operation of the existing cyclic direct simple shear, cyclic triaxial/torsional and resonant column devices, and development of a new in situ shaking facility for full-scale soil and soil-structure systems. The centerpiece of this development plan was the acquisition of a geotechnical centrifuge for static and seismic model testing of soil and soil-structure systems. This medium-size (100 g-ton, 2.5m nominal radius) centrifuge is one of the largest of its type in the United States and is installed in a circular underground enclosure 7m in diameter by 3m in height, connected by a tunnel to the rest of the Class of 1933 Laboratory. Small and large in-flight earthquake simulators, as well as special containers to simulate the seismic in situ conditions, have been designed/constructed at Rensselaer and successfully used in several projects. Rensselaer's Geotechnical Centrifuge Research Center has been formed to coordinate the research and administer the centrifuge-related activities. (Dobry/Elgamal/Zimmie)
Earthquake Response of Dams The earthquake response of two Mexican earth dams is investigated. The dams have undergone a number of significant earthquakes over the last 10 years including the event of September 1985. the investigation is motivated by the availablity of intensive documented information about the properties of the two dams and their response during each shaking event. The current condition of the dams and the consequnces of future earthquakes will be assessed. (Elgamal)
Liquefaction Failure of Loose Alluvium and Hydraulic Fill Centrifuge model studies are conducted of the earthquake response and liquefaction failure of very soft saturated granular soil. Silty sand is deposited in layers in water, allowing for segregation, thus simulating the soil density and fabric of many natural and artifical soil deposits. Models of small embankments are placed on this poor foundation soil. The system is first consolidated by centrifuge spinning, and is then shaken in flight. Accelerations, pore water pressures, and ground deformations are monitored during and after shaking. Tests are conducted with ans without implementing ground remediation measures. (Dobry)
Permanent Ground Deformation Deformations Due to Earthquakes An engineering method is being developed for the evaluation of permanent ground deformations caused by seismic loading. Large displacements and cracking of the ground surface have been observed after earthquakes in the United States, Japan, and other countries typically associated with liquefaction of saturated sandy soil. The research involves cyclic loading tests of saturated sand samples, modeling of the stress-strain-strenght and pore water buildup behavior of the soil, shaking table/centrifuge test of modeling, and detailed study of some well-documented case histories. Permanent deformations in slopeds and earth dams due to earthquake action are also studied. A well-instrumented earth dam where significant crest movements have been observed after several earthquakes is analyzed in detail using Newmark's method and other analytical techniques. (Dobry/Elgamal)
Centrifuge Earthquake Studies of Sand Liquefaction The earthquake liquefaction response of water-saturated sand is studied in the centrifuge. Rigid-wall containers and laminar boxes (stacked-ring devices) are used. Parameters varied and configurations tested include: horizonal and sloping homogeneous deposits with a slit or clay layer on top of the sand, shallow foundations on both homogeneous and 2-layer deposits, shallow foundations on saturated compacted sand surrounded by loose liquefiable sand, and use as pore fluid of a glycerine-water mixture with the appropriate viscosity to satisfy the corresponding scaling laws. (Dobry)
Geotechnical System Identification During Earthquakes A novel, simple, effective procedure has been developed to analyze seismic accelerations recorded by downhole (beneath the ground surface) vertical instrumentation arrays. Such arrays are being increasingly deployed in seismically active area including Taiwan, Japan, and the United States. Seismic histories of stresses and strains are calculated at various levels beneath the ground during each recorded earthquake. Significant insights are gained into the actual dynamic soil response on a load-cycle-by-cyle basis. The analysis procedure offer a particularly attractive approach to investigate results from seismic centrifuge experiments as well. Dynamic soil properties (resonances, shear wave velocities, small and large strain cyclic response, and progressive loss of strength due to liquefaction) are easily estimated at various depths beneath the ground. (Elgamal)
Reliability of Earth Retaining Structures Under Seismic Loading Attemptes are made to quantify the magnitude and distribution of forces imposed upon earth retaining structures during earthquakes and to asses their reliability and their dependence on the seimic characteristics of a structure. (Grivas)
In Situ Dynamic Testing of Retaining Walls In view of the virtual absence of quantitative earthquake data for retaining walls, full-scale dynamic testing is undertaken to evaluate in situ dynamic testing response characteristics. Reinsforced concrete earth walls have been tested. The full-scale testing results will be used for calibrating newly developed analytical/numerical methods to be used for design. (Elgamal)
Centrifuge Earthquake Studies of Bridge Foundations and Abutments In this multi-year work, sponsored by the Federal Highway Administration and the National Center for Earthquake Engineering Research (NCEER), several bridge foundation and abutment systems are modeled and seismically shaken in the centrifuge. Based on these tests and corresponding interpretations and analytical modeling, engineering recommendations and national guidelines are developed for seismic retrofitting of existing bridges and design of new bridges. Systems studies include: (1)p-y curves and lateral capacity of pile foundations in water-saturated sand before, during, and after liquefaction; (2)lateral spreading dure to liquefaction and its effect on abutment and bridge deck; (3)lateral stiffness, damping and capacity of seat-type abutments; and (4)relative contributions of the various prarts of a pile-cap system to the lateral stiffness, damping, capacity of the foundation. (Dobry)
Radioactive Contaminant Transport The transport of radioactive waste contaminants through groundwater and undersea repositories is being studied by using the geotechnical centrifuge, to simulate long periods of time. (Zimmie)
Landfill Cover Performance Unconventional cover material, for example waste paper sludge, is being used to close landfills. the project includes laboratory tests and field instrumentation of actual landfills. (Zimmie)
Freeze/Thaw Effects on Landfill Cover Soils Freezing and thawing can cause the clay covers of landfills to crack, allowing contaminants and precipitation to pass through the cover. Freeze/thaw effects are studied in the laboratory and verified by long-term studies of instrumented lanfills. (Zimmie)
Micromechanics and Constitutive Relation of Cohesionless Soil The stress-strain response of cohesionless soil is studied for a variety of static and cyclic loading conditions, both dramined and undrained. Laboratory experiments, analytical studies, and distinct element computer simulations of regular and random arrays of rough elatic shperes, are used. The results are expressed within a continuum mechanics framework in an effort to develop a general constitutive relation for cohesionless soil. (Dobry)
Expert Systems in Civil Engineering Knowlegde-based expert systems are developed and utilized in order to assess performance, diagnose damage, and establish rehabilitation procedures for civil engineering structures. (Grivas)
Pavement Management System Rensselaer researchers work closely with NYS Thruway personnel to develop and implement a pavement management system (PMS) for the nation's longest toll road. The plan consists of three phases: (1) expand the PMS condition assessment procedures to include the expanded Thruway inventory, provide additional studies on traverse cracking, rutting, and toughness, and utilize image processing techniques for crack detection; (2) refinement of the developed decision methodologies to reflect changes in the condition assessment process and suggested improvements from evaluation and operational use of methods; (3) modify, covert, and integrate component stand-alone computer programs and the Pavement Integrated DataBase System into an integrated system. (Grivas)
Adaptive Real-Time Control Strategies for Highway Networks This is a series of projects spanning more than seven years directed toward the development of advanced traffic management systems for Intelligent Vehicle Highway System (IVHS). Instrumentation, communication, and control systems are the principle focus. Emerging sensor technologies are exploited, as well as advanced control tools such as neural nets, expert systems, and fuzzy logic. (List)
Evaluation Tools for Goods Mobility Improvements This effort, spanning four years, focuses on creating advanced tools and techniques that help assess the benefits and costs of network improvements that enhance goods mobility in urban areas. The first project was directed toward estimating multi-class truck trip matrices from disparate observations. Current efforts focus on creating network models that can evaluate the benefits and costs of system enhancements like dedicated truck-only lanes on freeways, shared use of auto-only parkways by anto-like commercial vehicles, construction of truck-only entrance and exit ramps, geometric improvements in interchanges, and motorist information systems for truck drivers. Geographic Information System (GIS) is sued extensively in tool building, database management, and results presentation. (List)
Decision Support Systems for Hazardous Materials Logistics This series of projects spanning five years is directed toward developing GIS-based analysis tools for hazardous materials logistics problems. Routing is of particular interest as is the siting of emergency response teams, and the siting of waste treatment facilities. GIS plays a central role, as does multi-objective routing and multi-objective siting. Basic research on new analysis tools and techniques is supplemented by case studies that focus on analyzing shipments of spend nuclear fuel, retired nuclear weapons, and hazardous materials and wastes. (List)
Restrictive Routing on Highway Networks This recent pair of projects focuses on developing faster, more efficient ways to process permit requests for overweight, over-dimension trucks, including approval of routes to be followed. Close integration between highway condition databases, GIS, and routing algorithms forms the core of the decision support system. Real-time data exchange is also being explored and advanced, with the objective of achieving direct machine-to-machine interchange between requestor and authorizing agency. An eye toward coordination of such permit approvals on a multi-state basis is included. (List)
Using Interactive Simulation to Study the Impacts of Advanced Traveler Information System on Driver Behavior This project focuses on developing more robust models of driver behavior to take robust model of driver behaviors as well as dynamics of day-to-day adaptations of behavior are considered. Interactive microcomputer simulation techniques are employed for coducting in-laboratory experiments. (Adler)
Dynamic Network Simulation Current network simulators rely on relatively simplistic models of driver behavior for assigning and routing vehicles. In response to the development and deployment of IVHS technologies it is necessary to integrate simulation programs with more complex models that can account for route switching and information acquisition behavior. (Adler)