Engineering Tools

Specialized Software Tools

Ghiocel Predictive Technologies, Inc. has developed a series of engineering computational tools that include computer codes for advanced engineering analysis including finite element techniques, stochastic response modeling, stochastic-optimization for complex problems, reliability calculations for mechanical systems and components under progressive stochastic damage produced by low-cycle and high-cycle fatigue and/or corrosion, engine health risk management in heavy transient operating conditions, stochastic seismic wave in propagation in soil media, dynamic soil-structure interaction, blast wave and missile effects on structures and other engineering analysis modeling aspects. Below is a short list of the computer codes that we promote for sale as commercial software packages or as customized, user-friendly in-house implementations for industry clients.

Software Packages

ACS SASSI

It is a highly specialized user-friendly, finite element computer code on the MS Windows PC platforms for performing efficiently linear or nonlinear 3D dynamic soil-structure interaction (SSI) analyses for complex geometry foundations subjected to spatially varying incoherent motions or multiple support seismic excitations. ACS SASSI that is a modern software coded using advanced features of VC++ and Fortran90+, languages, provides a set of totally new engineering capabilities for SSI analysis in comparison with the original SASSI developed by Professor J. Lysmer and co-workers at University of California at Berkeley.

ACS SASSI V4.2 COMING IN FALL 2020:
The new ACS SASSI V4.2 is tentatively planned for release by November. A detailed technical newsletter will be available on this page later this month. For now, here is a short slide presentation entitled:  "New ACS SASSI NQA V4.2 Capabilities for Improving SSI Analysis of Embedded Structures and SMRs Based on ASCE 4-16 and JEAC 4601-2015 Guidelines for Severe Earthquakes".

ACS SASSI V4  BRIEF DESCRIPTION OF TECHNICAL CAPABILITIES:
The ACS SASSI V4 is a state-of-the-art engineering analysis tool for performing the seismic analysis of complex, surface, embedded, deeply embedded or buried structures. ACS SASS offers a good engineering balance between numerical sophistication and engineering practice with the intention to provide an affordable safe design for the hazardous facility structures. ACS SASSI includes a totally unique set  of SSI analysis capabilities not existent in other specialized SSI codes, that extended the original linearized SASSI Flexible Volume methodology to nonlinear soil and nonlinear structures, and also probabilistic SRA and SSI, also including incoherent seismic waves using advanced stochastic simulation algorithms. The many added specialized capabilities made ACS SASSI the most complete engineering analysis tool for the seismic SSI analysis of safety-related structures of hazardous facilities. The recent versions included automatic section-cut capabilities and back-bone curve generation for RC walls, and a powerful ACS SASSI-ANSYS integration capability that permits to use the ANSYS modeling capabilities, such as dynamic super-elements or fluid elements necessary for a refined  seismic fluid-SSI analysis. It also includes special 3D HVD base-isolators (acting in horizontal and vertical directions) which outperform the traditional 2D-space LRB (only in horizontal directions), especially in vertical direction, and for incoherent seismic motions that could affect severely the efficiency of base-isolation systems.

The current ACS SASSI NQA Version 4 software includes in addition to the main software three additional advanced SSI analysis options including Option A-AA (ACS SASSI integration with ANSYS), Option PRO (probabilistic site response and SSI per ASCE 4-16 Sections 2 and 5), Option NON (nonlinear concrete shearwall buildings per ASCE 4-16 Section 3) and Option RVT-SIM (SSI analysis based on the random vibration theory combined with stochastic simulation), which are described below:.

i) Option A-AA. The Option A for ACS SASSI-ANSYS interfacing includes an automatic export of the seismic SSI boundary conditions for performing a detailed nonlinear or linear ANSYS stress SSI analysis using either quasi-static or dynamic refined FE models, or computing soil pressure on baseslabs and embedded walls including soil separation effects. The Option AA for the advanced ACS SASSI-ANSYS integration permits to run SSI analysis using directly ANSYS FEA models. The Option AA ANSYS models could include advanced ANSYS FE types, pipes, shells including shear flexibility, coupled nodes, constraint equations, MPC elements, and even fluid elements (FLUID80) and super-elements (MATRIX50). Option AA uses directly the ANSYS FE model dynamic matrices with no need for model conversion to ACS SASSI. More recently, the Option AA includes two SSI analysis options: 1) The Option AA that uses the ACS SASSI solver for the SSI solution, and 2) The Option AA-REDUCE or AA-R that uses the ANSYS solver for the SSI solution in complex frequency. The Option AA-R capability was introduced starting with the 4.1 version. The Option AA-R largely extends the Option AA capability of using directly ANSYS structure FE models for seismic SSI analysis. The Option AA-R ANSYS models are applicable only to the ANSYS Harmonic SSI analysis in complex frequency. To make Option AA-R more practical a reduced-size soil impedance matrix and a reduced-size seismic load vector are used, based on the condensation of the excavated soil impedance full matrix done in the ANALYS module. The frequency-dependent condensed excavated soil matrix and the reduced load vector produced by ACS SASSI is exported to ANSYS as a super-element (MATRIX50 element) that is attached to the ANSYS structure FE model. Option AA-R is a particular useful tool for performing ANSYS Fluid-SSI analysis (including FLUID30 elements) using SASSI methodology.

ii) Option PRO for probabilistic site response analysis (PSRA) and SSI analysis (PSSIA) using efficient LHS simulations. Option PRO is consistent with probabilistic site response and SSI procedures in the coming-soon ASCE 04-2016 standard (in Sections 2 and 5) and the USNRC guidance for computing the FIRS for new licensing applications. The Option PRO probabilistic modelling includes: i) Response spectra shape model for the seismic motion input, ii) Soil shear wave velocity Vs and hysteretic damping D profiles, defined for each soil layer for low shear strain values, iii) Soil shear modulus G and hysteretic damping D, as random functions of the soil shear strain values for each soil layer, and iv) Equivalent linear values for the effective structural stiffness and damping for each group of elements depending on the stress levels in different parts of the structure.

iii) Option NON or nonlinear structure SSI analysis uses a fast hybrid time-complex frequency approach based on a iterative equivalent-linearization for each nonlinear RC wall structure SSI analysis as functions of the local deformation of the wall panels. It is hundreds of times faster and much more robust than the time-domain integration nonlinear SSI approaches available in other FEA codes. Option NON is applicable to the reinforced concrete structures by simulating the concrete cracking and post-cracking behavior in low-rise shearwalls for design-level or beyond-design-level seismic inputs, or to model the hysteretic behavior of the seismic base-isolators, as LRB or FP isolators. The new upgrade of Option NON to be released in November 2020  includes a significant new development with several new software modules, to include both shear and bending effects in place walls based on the latest engineering practices in US and Japan (ACI-318, ASCE 4/43 standards in US, and JEAC 4601 and AIJ RC standards in Japan).

iv) Option RVT-SIM. The RVT-SIM approach combines the Random Vibration Theory (RVT) in complex frequency domain with the stochastic simulation (SIM) in time domain for efficiently computing the maximum SSI responses. The RVT-SIM approach input is the ground response spectra (GRS). No input time histories are required in this approach. The RVT-SIM approach uses the input GRS to compute the ground power spectral density (GPSD), and then, used the stochastic simulation to compute the maximum SSI responses based on the computed response power spectral density (RPSD).

v) Option UPLIFT is based on the Japan JEAC 4601-2015 standard recommendations. It uses two nonlinear uplift approaches based on the foundation uplift severity: 1) A simplified nonlinear uplift approach based on a nonlinear static uplift analysis, applicable if the base surface contact ratio is in the 65%-75% range, and 2) A refined nonlinear uplift approach based on a nonlinear time-domain dynamic uplift analysis, applicable if the surface contact ratio is in the 50%-65% range. For contact ratios above 75%, the linear SSI analysis results are considered reasonable accurate. The JEAC 4601 foundation uplift approaches were implemented in the ACS SASSI software by combining the equivalent-linearization of the overall SSI analysis in complex frequency with the nonlinear base uplift analysis occurring at the foundation-soil interface per the JEAC 4601-2015 standard.

ACS SASSI V3 2015 NEWSLETTER entitled "Engineering Advances for Deterministic and Probabilistic, Linear and Nonlinear Seismic SSI Analysis". The newletter describes some key implementations of the ACS SASSI software over last decade. Newer developments are described in more recent papers and presentation shown below.

RECENT PAPERS AND PRESENTATIONS ON THE ACS SASSI APPLICATIONS:

2020: DOE-NRC Natural Phenomena Hazards Meeting, US NRC Headquarters, Rockville, MD, October 20-22, 2020 (slide presentations)
"Nonlinear Seismic SSI for Reinforced Concrete Buildings in Accordance with Engineering Practices in US and Japan"
"Seismic SSI Analysis of RB Complex on Pile Foundation Including Soil Nonlinear Hysteretic Behavior"
"A Comparative Seismic SSI Study for A Nuclear Island Sitting on Different Base-Isolation Systems"

2020: Architecture Institute of Japan (AIJ) Conference, September 2020 (draft papers):
"3D SSI Analysis of Nuclear Islands Including Foundation Uplift Effects Based on JEAC 4601-2015 Recommendations"


2019: The SMiRT25 Conference, Division III, Charlotte, NC, USA, August 4-9 (papers and slide presentations):
"Sensitivity Studies for Nuclear Island Founded on Piles Including Effects of Seismic Motion Spatial Variation and Local Nonlinear Behavior" and slides are here.
"Probabilistic Seismic SSI Analysis Sensitivity Studies for Base-Isolated Nuclear Structures Subjected to Coherent and Incoherent Motions" and slides are here.
"Extending SASSI Methodology to Seismic SSI Analysis of NPP Buildings on Soil Deposits with Inclined Layering" and slides are here.

2019:  3-Days ACS SASSI V4 Training Notes for the US NRC (Part 1, Part 2 and Part 3), US NRC Headquarters, Rockville, MD, June 25-27, 2019.
Part 1: "ACS SASSI Modeling, Theory and Implementation" (slightly modified and reduced)
Part 2: "Advanced Options A-AA (Integration with ANSYS), PRO (Probabilistic SRA and SSI) and NON (Nonlinear concrete structures or base-isolated structures)" (slightly modified and reduced)
Part 3: "User Guide for ACS SASSI V4 Software & Demos" (slightly modified, without demos and example problems)

2018: Invited Technical Seminar Presentations for the US NRC (Session 1, Session 2 and Session 3), US NRC Headquarters, Rockville, MD, November 15, 2018.
Session 1: "An Overview of Seismic SSI Analysis for Nuclear Structures Based on Various Case SSI Studies" - 9:00am-10:00am
Session 2: "Studies on Seismic SSI Effects for Deeply Embedded Nuclear Reactors, as SMRs" - 10:15am-12:00am (proprietary, not available)
Session 3: "ACS SASSI Capabilities and Options Including Demo Sample Problems" - 1:00pm-3:00pm

2018: DOE-NRC Joint Natural Phenomena Hazards Meeting, US NRC Headquarters, Rockville, MD, October 23-24, 2018 (slide presentations)
ASCE 4-16 Standard-Based Probabilistic Seismic SSI Analysis. Part 1 Application for Design Basis Earthquake (DBE)
ASCE 4-16 Standard-Based Probabilistic Seismic SSI Analysis. Part 1 Application for Beyond Design Basis Earthquake (BDBE)
Limitation of RVT SASSI Approach for Application to Seismic SSI Analysis of Nuclear Structures
Probabilistic Simulation Procedure for Developing Site-Specific Plane-Wave Coherence Functions

2018: 2nd International Nuclear Power Plants: Structures, Risk & Decommissioning, NUPP2018, London, UK, June 11-12, 2018 (papers)
Seismic SSI Effects for Deeply Embedded Nuclear Islands Surrounded by Soft Backfill Soil
Evaluation of Reinforced Concrete Cracking and Post-Cracking Behavior for Nuclear Buildings Under Design and Beyond Design Earthquake Levels
ASCE 4-16 Standard-Based Probabilistic Seismic SSI Analysis for Design-Basis and Fragility Analysis

2017: The SMiRT24 Conference, Special Session SS6 on "ASCE 4-16 BASED PROBABILISTIC/NONLINEAR SOIL-STRUCTURE INTERACTION, Seoul, Korea August 2017 (papers):
"New ASCE 4 Standard-Based Probabilistic Soil-Structure Interaction (SSI) Analysis for Seismic Design-Basis Analysis and Fragility Calculations"
"Automatic Computation of the Strain-Dependent Concrete Cracking Pattern for Nuclear Structures for Site Specific Applications"
"Fast Nonlinear Seismic SSI Analysis of Low-Rise Concrete Shearwall Buildings for Design-level (DBE) and Beyond Design-Level (BDBE)"
"Understanding Seismic Motion Incoherency Effects on SSI and SSSI Responses of Nuclear Structures"
"Accurate Linear and Nonlinear Seismic SSI Analysis Based on ANSYS FE Modeling by Extending SASSI Methodology"
"Seismic SSI Effects on Design of Curved Sliders for Base-Isolation and Recentering Capability of Rectagular Shearwall Structures"

2016: 10th Nuclear Plants Current Issues Symposium: Assuring Safety against Natural Hazards through Innovation & Cost Control, Charlotte, North Carolina, December 11-14, 2016 (slide presentation).
 "New ASCE 4-Based Probabilistic Nonlinear SSI Analysis for Improving Seismic Fragility Computations"

2016: 2-Day U.S. Department of Energy Natural Phenomena Hazards Meeting, Germantown, MD, USA, October 18-19, 2016, Session on "Soil-Structure Interaction" (slide presentations)
"Fast Nonlinear Seismic SSI Analysis for Low-Rise Concrete Shearwall Buildings for Design-Basis and Beyond Design Application"
"Critical Modeling and Implementation Aspects for Seismic Incoherent SSI Analysis of Nuclear Structures with Surface and Embedded Foundations for Rock and Soil Sites"
"Probabilistic SSI Analysis Per ASCE 4-16 Standard; A Significant Improvement for Seismic Design Basis Analysis and Fragility Calculations"

2016: The 3rd Annual ACS SASSI Workshop in Tokyo, Japan, May 12-13, 2016 (slide presentation). Herein is the 1st day wokshop presentation on  "ACS SASSI Application to Seismic SoilStructure Interaction (SSI) Analysis of Highway Bridge Structure"

2015: Technical presentation on "Sensitivity Studies for Evaluating SSI Effects for Seismically Base-Isolated NPP Structures." for the ASCE Dynamic Analysis Nuclear Structure (DANS) working group during the ASCE 43 standard meeting in San Diego, November 6, 2015, PART 1:Deterministic SSI Analysis and PART 2:Probabilistic SSI Analysis The seismic SSI analysis for the base-isolated RB complex was performed using the advanced ACS SASSI Options NON and PRO. Please see animation for coherent and incoherent inputs for the base-isolated RB complex.

2015: The SMiRT23 Conference, Manchester UK, August 2015 (papers):
"SASSI Flexible Volume Substructuring Methods for Deeply Embedded Structures; Selection of Excavated Soil Interaction Nodes and Element Meshing"
"Fast Nonlinear Seismic SSI Analysis Using A Hybrid Time-Complex Frequency Approach for Low-Rise Nuclear Concrete Shearwall Buildings"
"Probabilistic-Deterministic SSI Studies for Surface and Embedded Nuclear Structures on Soil and Rock Sites"
"Seismic Motion Incoherency Effects on Soil-Structure Interaction (SSI) and Structure-Soil-Structure Interaction (SSSI) of Nuclear Structures for Different Soil Site Conditions"
"Random Vibration Theory (RVT) Based SASSI Analysis for Nuclear Structures Founded on Soil and Rock Sites"

2015: The 2nd Annual ACS SASSI Workshop in Tokyo, Japan, April 14, 2015, on "Engineering Advances Implemented in ACS SASSI Version 3.0 for Seismic SSI Analysis of Nuclear Structures"(slide presentations). The SSI wokshop presentation slides can be downloaded here by clicking on Part 1 and Part 2

2014: 2-Day U.S. Department of Energy Natural Phenomena Hazards Meeting, Germantown, MD, USA, October 21-22, 2014, Session on "Soil-Structure Interaction" (slide presentations)
"Effects of Seismic Motion Incoherency on SSI and SSSI Responses of Nuclear Structures for Different Soil Site Conditions"
"Comparative Probabilistic-Deterministic and RVT-based SASSI Analyses of Nuclear Structures for Soil and Rock Sites"
"SASSI Methodology-Based Sensitivity Studies for Deeply Embedded Structures Such As Small Modular Reactors (SMRs)"

2014: The 1st Annual ACS SASSI Workshop in Tokyo, Japan, March 24-25, 2014, on "Recent Advances Implemented in ACS SASSI Software for Linear and Nonlinear Seismic Soil-Structure Interaction (SSI) Analysis"(slide presentations). The wokshop presentation slides can be downloaded here by clicking on Part 1 and Part 2

2014: ACS SASSI Workshop in Shanghai, China, April 3, 2014, on "Recent Advances in Seismic Soil-Structure Interaction (SSI) Analysis of Special Structures Using ACS SASSI"(slide presentations). The wokshop presentation slides can be downloaded here by clicking here

2014: The 2nd European Conference on Earthquake Engineering and Seismology, for Civil Engineering Structures, August 2014 (papers):
"Nonlinear Seismic Soil-Structure Interaction (SSI) Analysis Using An Efficient Complex Frequency Approach"
"Seismic Structure-Soil-Structure Interaction (SSSI) Effects for Dense Urban Areas" collaboration with "Dan Ghiocel International Research Center", Bucharest, Romania
"Incoherent Soil-Structure Interaction (SSI) Effects for A 242M Long Concrete Founded on Deep Piles" collaboration with "Dan Ghiocel International Research Center", Bucharest, Romania

2013: The SMiRT22 Conference, for NPP Structures, August 2013 (papers):
"Validation of Modified Subtraction Method for Seismic SSI Analysis of Large-Size Embedded Nuclear Islands" and associated slides
"Comparative Probabilistic-Deterministic Investigations for Evaluation of Seismic Soil-Structure Response" and associated slides
"Efficient Probabilistic Seismic Soil-Structure Interaction(SSI) Analysis for Nuclear Structures Using A Reduced-Order Modeling in Probabilistic Space" and associated slides
"Comparative Studies on Seismic Incoherent SSI Analysis Methodologies" and associated slides
"Structure-Soil-Structure Interaction Effects for Two Heavy NPP Buildings With Large-Size Embedded Foundations"
"Generic Input for Standard Seismic Design of Nuclear Power Plants"
"Fast Nonlinear Seismic Soil-Structure Interaction (SSI) Analysis of Nuclear Shearwall Concrete Structures Subjected to Review Level Earthquake"
"Simplified Modeling of Effects of Concrete Cracking on Out-of-Plane Vibrations of Floors"

2011: ACS SASSI Related Papers Presented at the SMiRT21 and ASEM11 Conferences, for NPP Structures, Fall 2011 (papers)
Seismic Incoherent Soil-Structure Analysis of A Reactor Building Complex on A Rock Site
Seismic Soil-Structure Interaction (SSI) Effects for Large-Size Surface and Embedded Nuclear Facility Structures

2010: OECD NEA/IAEA SSI Workshop, Ottawa, October 6-8, 2010 (papers):
Seismic SSI Response of Reactor Building Structures
Seismic Motion Incoherency Effects for Nuclear Complex Structures On Different Soil Site Conditions
Seismic Motion Incoherency Effects for CANDU Reactor Building Structure
EPRI AP1000 NI Model Studies on Seismic Structure-Soil-Structure Interaction (SSSI) Effects

2009: ACS SASSI Related Papers Presented at ICOSSAR09, SMIRT20 and ASME PVP2009 Conferences, in July-August 2009 (papers):
ICOSSAR09 Paper on Seismic Motion Incoherency Effects for Nuclear Island Complexes
SMIRT20 Paper on AP1000 Nuclear Island Complex
SMIRT20 Paper on EPRI AP1000 NI Stick Model
PVP2009 Paper on Typical PWR Reactor Building

2007: ACS SASSI Related Papers Presented at SMiRT19 Conference, August 2007 (papers):
"Seismic Ground Motion Incoherency Effects on Soil-Structure Interaction Response of NPP Building Structures"

TECHNICAL NOTES on Seismic SSI Analysis and Modeling for Nuclear Island Applications:

FAST NONLINEAR SEISMIC SOIL-STRUCTURE INTERACTION (SSI) ANALYSIS IN COMPLEX FREQUENCY DOMAIN, Technical Note GPT-001-10-01-2013, October 1, 2013 and associated slides
THE SASSI FLEXIBLE VOLUME SUBSTRUCTURING METHODOLOGIES, Technical Note GPT-001-430-2012, April 30, 2012. Please see animations of the excavated soil motion for an embedded RB complex foundation using DM , SM and MSM methods.
SOME INSIGHTS ON FREQUENCY VS. TIME-DOMAIN APPROACHES FOR SEISMIC SSI ANALYSIS OF NPP STRUCTURES, Technical Note GPT-001-201-2012, February 1, 2012

1998-2002: Selected Papers on ACS SASSI Application for Probabilistic Seismic SSI and Seismic Fragility Analysis for Nuclear Structures:
Uncertainties of Seismic Soil-Structure Interaction Analysis: Significance, Modeling and Examples, US-Japan SSI Workshop, USGS, 1998
Stochastic Finite-Element Analysis of Seismic Soil–Structure Interaction, Journal of Engineerings Mechanics, ASCE, 2002

2004-2005: Selected Papers on ACS SASSI Application for Seismic Analysis of Large Span Concrete Bridges on Piles in New York City and Washington D.C., USA, and Japan:
Seismic Geotechnical Investigations of Bridges in New York City, 2004
Seismic Soil-Foundation Interaction Analyses of the New Woodrow Wilson Bridge, 2005
Load Bearing Mechanism of Piled Raft Foundation during Earthquakes, 2004

2011: HAND-NOTES FROM ACS SASSI TRAINING in January 2011: 3-Day ACS SASSI Training at the North Marriott Convention Center, Bethesda, MD, in the Washington D.C. area (across US NRC building), January 25-27, 2011, on "ACS SASSI Application to Linear and Nonlinear Seismic SSI Analysis of Nuclear Structures Subjected to Coherent and Incoherent Inputs". Please contact Dr. Dan M. Ghiocel, Instructor, at dan.ghiocel@ghiocel-tech.com if you have any question on the SSI training. The hand-notes could be downloaded here by clicking on Part 1-Day 1 and Part 2-Day 2-3 The list of the 21 atendees of the 3-day SSI training is available here. A brief professional profile of the Instructor is provided here.

STRUCTURE DEFORMED SHAPE AND STRESS CONTOUR ANIMATIONS:

  • Comparison between SSSI Effects for Coherent and Incoherent Motions
  • Embedded Nuclear Reactor Building Acceleration Response
  • Nuclear Standard Plant Seismic Response Animation
  • Large-Size Structure Acceleration Under Coherent Input - Below Basemat View
  • Large-Size Structure Acceleration Under Incoherent Input with Wave Passage
  • Seismic Pressure Fluctuation for Y-Input on An Embedded Foundation
  • Deeply Embedded Structure Acceleration Deformed Shape Under Coherent Input
  • Deeply Embedded Structure Acceleration Deformed Shape Under Incoherent Input
  • Deeply Embedded Structure SYY Stress in Walls Under Coherent Input
  • Deeply Embedded Structure SYY Stress in Walls Under Incoherent Input
  • EPRI AP1000 Stick Coherent Displacement on Rock Site wrt to Free-Field Input
  • EPRI AP1000 Stick Incoherent Displacement on Rock Site wrt to Free-Field Input
  • Embedded EPRI AP1000 Stick Acceleration for A Soft Soil Under Coherent Input
  • Embedded EPRI AP1000 Stick Acceleration for A Soft Soil Under Incoherent Input
  • EPRI AP1000 Stick and Annex Bldg. Coherent Displacements wrt FF Input
  • EPRI AP1000 Stick and Annex Bldg. Incoherent Displacements wrt FF Input
    http://www.ghiocel-tech.com/storage/document/14/58/c7/ec551878b2b55797051e45d517effc8d.news-summary-acs-sassi-v-4-2-august-25-2020-.pdf

ProCORFA

It is a highly specialized, Windows XP, user-friendly computer code for performing probabilistic life, and reliability prediction for aircraft and vehicle structures subjected to progressive stochastic corrosion-fatigue damage including the effects of maintenance activities. In addition to stochastic modeling and risk prediction capabilities, ProCORFA includes a stochastic cost modeling module. ProCORFA has a fully integrated software interface with the USAF AFGROW code for fatigue crack propagation computation. ProCORFA package also includes an interface with ANSYS code that is programmed in ANSYS ADPL language. ProCORFA is being developed in collaboration with STI Technologies and Cornell University. ProCORFA is programmed in Visual Basic and Fortran90.

Description

Slide Presentation

Related Paper

Animated Demo

GEOMIS

It is a highly specialized computer code for performing extremely fast and accurate mistuning analysis of bladed disk assemblies of gas turbine engines or power turbines. GEOMIS has the unique capability of considering the blade geometry mistuning effects due inherent manufacturing deviations on turbine blade-disk system vibration. GEOMIS performs geometry mistuning analysis using an efficient reduced-order modeling (ROM) based on “iterative eigensubpace projection” (IES) and "stochastic perturbation matrix" (SPM) approach.

GEOMIS is intimately interfaced with the ANSYS code that is used for bladed-disk system finite element modeling. Both the IES and SPM ROMs were developed by GP Technologies under its own internal resources. No publication is available for IES, and only a single publication is available for SPM (but only for mistuning analysis directly in the complex frequency domain, not in the modal domain - click on "related paper" link to see the paper on SPM). Both IES and SPM are very accurate for both frequency and geometry bladed-disk mistuning predictions. Both IES and SPM do not need any preliminary sector frequency calculations that provide a significant relief to the structure analyst.

Also, both IES and SPM do not require any preliminary work for identification and separation of system modes in isolated mode families which many times is an almost an impossible task for the analyst, especially for frequency ranges in which mistuned mode frequencies of different mode families interfere in a unknow, random pattern. Under "Animated Demo" selection a prototype MATLAB software version is shown. The full capability version of the GEOMIS code is programmed in VC++ and Fortran90.

Slide Presentation

Related Paper

Animated Demo

BladeHCF

It is a highly integrated, graphical computational environment for preforming probabilistic forced response and failure risk assessment for turbine engine bladed-disk assemblies that are subjected to high-cycle fatigue (HCF). The HCF damage occurs due to the structural vibration of these assemblies due to steady and unsteady gas pressure fluctuations on rotating blades. BladeHCF is a user-friendly, object-oriented, prototype software developed under the MATLAB/SIMULINK environment that can be easily adapted to various advanced turbine design, analysis and risk prediction applications.

The BladeHCF structure is modular and incorporates a number of graphical computational modules. BladeHCF uses ANSYS finite element code for steady and unsteady structural stress analysis. Aero-forcing is defined deterministically or probabilistically using simple engineering calculations based on aeromechanical tests. Brief animated demos for different graphical computational modules can be seen by clicking on Blade Geometry Variation module, Preliminary Deterministic System Force Response module, Probabilistic System Forced Response module, and Blade HCF Risk Prediction module.

It should be noted that GEOMIS code (please see above) that provides unique computational capabilities using reduced-order modeling for performing efficient and accurate geometry-based mistuning analyses of bladed-disk assemblies is included as a part of BladeHCF, namely within the Probabilistic System Forced Response module. Blade HCF risks are predicted using the probabilistic Goodman diagram failure criteria. Stochastic modeling uncertainty effects on probabilistic blade stresses due to small sample size effects, i.e. limited number of measured blades/rotors are included and used to define HCF risk variation bounds. BladeHCF also includes algorithms for aggregation of various information sources coming from computational blade stress/strain predictions, available test data, i.e. strain-gage and/or rig test data, and expert opinions.

Related Paper

Animated Demo

BLASTEX

It is a set of five highly specialized, Windows XP interactive, easy-to-use computer programs for a rapid evaluation of typical explosion blast effects on buildings, vehicles and surrounding people. The five computer codes are designed to be used by non-experts in blast physics and non-engineers. An earlier version of BLASTEX codes was distributed at a number of police departments, government agencies and national labs. The distribution of the BLASTEX package is limited to the US government agencies or institutions and national labs.

Description

ProMACOR

It is a highly specialized, Windows XP interactive, user-friendly computer code for performing probabilistic life, and reliability prediction for gas turbine engine blades subjected to low-cycle fatigue (LCF) and high-cycle fatigue (HCF) damage including the uncertainties associated with periodic maintenance inspections. For computing LCF-HCF interaction effects, ProMACOR uses advanced nonlinear damage models. Effects of random foreign object impacts on blade can also be included using stochastic simulation. ProMACOR is being developed together with STI Technologies. ProMACOR is not available as an integrated commercial package for sale. We are interested to work with gas turbine engine manufacturers to develop in-house customized versions for them.

Related Paper

StoFIS

It is a collection of software modules and libraries that can be integrated for performing in-flight risk-based fault diagnostics and prognostics in aircraft jet engines. To capture the complex functional stochastic relationships between different engine performance parameters or statistical features of vibration measurements, StoFIS combines advanced stochastic modeling with artificial intelligence tools for engine health risk management. StoFIS is an adaptive stochastic-fuzzy network-based inference and prediction system. Although, the software is based on complex stochastic approximation and prediction techniques, its output is simple, easy to interpret and highly practical. The user views probabilistic predictions interms of simple reliability metrics that can be easily interpreted for maintenance decisions. StoFIS has been developed together with STI Technologies. StoFIS is not available for sale as an integrated commercial package. We are interested to work with aircraft and helicopter engine manufacturers to develop refined in-house customized versions for them.

Slide Presentation

Related Paper

StoOPT

It is a collection of powerful computational toolboxes for complex stochastic-optimization problems involving large number of uncertain variables and/or high nonlinear noisy responses. The StoOPT package uses advanced dynamic simulation based on multilevel Markov Chain Monte Carlo algorithms with gradient hints coming from moving particle inertia. Based on extensive testing of convergence robustness for finding the global extrema, the StoOPT algorithms outperform all other reputed stochastic-optimization algorithms. To take full advantage of these robust algorithms in our reliability-based design optimization analyses, we use these algorithms in conjunction with advanced response surface modeling techniques based on stochastic field models integrated in our StoRES software. StoOPT is not available for sale as an integrated commercial software package. We are interested to work with our industry customers to developed in-house customized implementations for them.

StoRES

It is a collection of computational toolboxes for approximating complex system response surfaces involving a large number of uncertain variables and/or high nonlinear noisy responses. The StoRES package uses advanced stochastic field models for response surface modeling including one-level, two-level and three-level hierarchical stochastic approximation models, MCMC simulation-based approximation models, statistical and fuzzy clustering-based interpolation models, (non-Gaussian) translation field models and spatial stochastic-interpolation models including Gaussian krigging and radial-basis functions. The StoRES approximation models applied in conjunction with the StoOPT simulation-based stochastic-optimization models provide a unique set of toolboxes for rapidly solving reliability-design optimization problems. Based on numerical investigations done in-house and in collaboration with University of Iowa, we noticed that our StoOPT-StoRES suite of algorithms can reduce the number of computational mechanics analyses (function evaluations), such as finite element analyses or computational fluid dynamics analyses, needed for performing a reliability-based design optimization by 4 to 8 times. StoOPT is not available for sale as an integrated commercial software package. We are interested to work with our industry customers to developed in-house customized implementations for them.

StoUNC

It is a collection of computational toolboxes based on new theoretical concepts that were developed in-house for incorporating epistemic uncertainties in probabilistic structural mechanics analyses. The new concepts are being built on the imprecise probability theory that addresses practical, real situations when available statistical data is limited or very limited. StoUNC is not available for sale as an integrated commercial software package. We are interested to work with our industry customers to developed in-house customized implementations for them.