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Events Archive
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MARPA Conference
September 29 to October 1, 2009
Renaissance Hotel, Las Vegas, NV
Frank Priscaro, VEXTEC VP of Marketing:
"Computer Modeling as the Test Bed of the 21st Century"
www.pmamarpa.com |
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AeroMat 2009 Conference
June 7 – 11, 2009, Dayton, Ohio
Session: Symposium on Materials/Structural State Awareness and Prognosis
Abstract # 1: Probabilistic Microstructural Model to Predict Dual Fatigue Mechanisms in AA 7050-T7451
Wednesday, June 10, 2009 2:30 pm
Presenter & Co-Author: Raja V. Pulikollu
Co-Authors: Ganapathi Krishnan, Robert G. Tryon, J. VEXTEC Corporation
Most current design analysis approaches assume material homogeneity and ignores the effects of microstructure on the reliability of aluminum components. VEXTEC has developed aluminum 7050-T7451 probabilistic microstructural model to predict dual crack initiation mechanisms, distribution of cracks and the fatigue life of varying component geometries. Crack coalescence and mission modeling capability is incorporated in the model.
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Abstract # 2: Physics-Based Model for Gear Health Prognosis
Thursday, June 11, 2009 9:00 am
Presenter & Co-Author: Raja V. Pulikollu
Co-Authors: Robert Mcdaniels, Richard Holmes, Robert G. Tryon VEXTEC Corporation
The Helicopter Integrated Diagnostic System has achieved a documented success rate of up to 70% in detecting faults. However, despite all the improvements in failure detection, the remaining 30% of faults are not diagnosed. VEXTEC has developed a physics-based model for detection of gear faults by modeling the effects of tooth bending, contact fatigue and lubrication on gear performance. The technology involves successful modeling of the gear material microstructure and the highly localized multi-axial stresses at tooth contact. The prognostic model is demonstrated through comparison of the modeling results with gear test data.
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2009 Machine Failure Prevention Technology Conference
Abstract # 1: Scaled Turbine Engine Testing for Cost-effective Health Prognosis
Richard Holmes, Thomas Brooks, Robert Tryon
Full scale gas turbine engine testing is expensive and time consuming. An efficient alternative is the use of low cost subscale engine testing that can simulate the conditions of a full-scale engine and its failure mechanisms. VEXTEC has developed scaled turbine engine tests as a platform to gather probabilistic data on multiple material failure mechanisms such as thermal mechanical fatigue, biaxial crack growth, creep and foreign object damage. These tests are efficient in terms of cost and schedule and provide insight into full scale engine behavior. Complex multi-axial stress fields and thermal environment typically observed in gas turbine engines are naturally reproduced in the scaled engine testing. Subscale engine testing is validated by comparing the test data with full scale engine testing results. This paper discusses the capabilities of the scaled engine and its benefits compared to full scale engine testing.
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Abstract # 2 : Physics-Based Gear Health Prognosis via Modeling
Richard Holmes, Rajasekhar V. Pulikollu, Robert Tryon
VEXTEC has developed a physics based methodology that accurately predicts the remaining useful life of gears to greatly reduce engineering design time and cost. Gears are one of the oldest mechanical devices but remain a critical component in many military and commercial applications. The fundamental approach to gear analysis continues to be based on empirical standards; therefore, today’s gear analysis methods cannot predict damage accumulation for conditions outside of the experimental basis. This is a key barrier to accurate assessment of wear, gear health or to prognosticate remaining useful life for complex loading scenarios. Another major flaw in the existing industry approach is that it assumes material homogeneity. A complex load state exists at the surface of meshing gear teeth. Surface stress gradients are very shallow, on length scales similar to the material’s microstructural constituents. Current approaches ignore the microstructure inhomogeneity in the highly stresses surface and often predict misleading results.
VEXTEC’s methodology accounts for arbitrarily sequenced variable amplitude loading. Damage accumulation in the form of nucleation and small-crack growth within the microstructure of the highly stressed surface is explicitly modeled by accounting for the grain (colony) size, grain orientation, micro-applied stress and micro-yield strength. VEXTEC’s crack models incorporate randomness using Monte Carlo probabilistic techniques. The computer simulation is set up with built-in material libraries and appropriate modeling linkages are established to predict the scatter in fatigue life. The probabilistic micromechanical approach is integrated with the CAPRI hertzian contact model developed by Dr. Thomas Farris of Purdue University. This model provides the localized loading at the sub-grain size necessary for the micromechanical approach to predict component durability from fretting fatigue. VEXTEC’s proprietary virtual simulation tool provides detailed insight into the gear component fatigue and reliability issues.
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11th Annual Gorham PMA-DER Conference
VEXTEC has developed a Physics based methodology that will accurately predict the certification-required durability information for repaired engine components. All All turbine engine repairs must be certified for each specific engine, component (e.g. blade), material, and type of repair. But the FAA has traditionally certified repair processes only after reviewing an extensive
amount of physical test data proving the validity of the repair. The trouble is, physical testing takes time – generally between 12 and 24 months. VEXTEC’s Virtual Life Management™ (VLM) simulation technology can predict the certification required durability information in as little as 60 to 90 days.
Component failure or wear-out is caused by a material breakdown within the repaired component. A repair is an assemblage of different materials connected together at the micro scale. At this level (an order of magnitude above the molecular level), microstructural analysis reveals that materials are made up of grains, and that these grains have a pattern. That pattern determines the
material’s strength, or lack thereof. Individual failures occur how, where and when the material microstructure breaks down due to stress. Using physical testing to determine the integrity of repairs is time consuming (often as much as 24 months), and inconclusive at best. Only VEXTEC can simulate 1000s of repaired parts, with all these microstructural differences at various stress levels, to predict the repair durability, in as little as 2 to 3 months.
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P-SAR CONFERENCE 2009
Abstract#1: Physics-Based Gear Health Prognosis via Modeling Coupled with Component Level Tests
Abstract#2: Prognosis model for predicting high cycle fatigue (HCF) in gas turbine blades
Abstract#3: Durability Analyses, Life Prediction, and Life Cycle Cost: A Systematic Approach |
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Abstract # 1
Submit Under “Mechanical Systems & Drives”
Physics-Based Gear Health Prognosis via Modeling Coupled with Component Level Tests
VEXTEC has developed a Physics based methodology that will accurately predict the remaining useful life of gears to greatly reduce engineering design time and cost. Gears are one of the oldest mechanical devices but remain a critical component in many military and commercial applications. The fundamental approach to gear analysis continues to be based on empirical standards; therefore, today’s gear analysis methods cannot predict damage accumulation on a cycle by cycle basis. This is a key barrier to accurate assessment of wear, gear health or to prognosticate its remaining useful life. A major flaw in the existing industry approach is that it assumes material homogeneity. This approach ignores the vast difference in microstructure between the brittle case hardened surface layer of the gear and its more ductile core.
VEXTEC’s methodology takes nucleation and small-crack growth regimes into specific account by modeling the grain size, grain orientation, micro-applied stress and micro-yield strength. VEXTEC’s crack models incorporate randomness using Monte Carlo probabilistic techniques. The computer simulation is set up with built-in material libraries and appropriate modeling linkages are established to predict the scatter in fatigue life. The probabilistic micromechanical approach is integrated with the CAPRI hertzian contact model developed by Dr. Thomas Farris of Purdue University. This code provides the localized loading at the sub-grain size necessary for the micromechanical approach to predict component durability from fretting fatigue. VEXTEC’s proprietary virtual prototyping tool significantly reduces engineering design costs while simultaneously providing a more detailed insight into the gear component fatigue and reliability issues.
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Abstract # 2
Prognostics & Health Management for Engines
Prognosis model for predicting high cycle fatigue (HCF) in gas turbine blades
VEXTEC has developed an innovative life prediction capability for gas turbine engines by incorporating microstructure failure mechanisms and foreign object damage (FOD) events into a consolidated model. This approach is capable of greater accuracy and offers unique capabilities not otherwise available. The VEXTEC approach also provides a lifing capability for situations where it is not possible to detect the damage state of the blade in service. The prognostics model (based on the material’s physics of failure) was validated with experimental data gathered on aero turbine blades and showed that the micromechanical models accurately predict fatigue crack growth and fatigue lives of the blades.
The simulated component Goodman methodology accurately predicts the high cycle fatigue resistance of turbine engine components under various vibratory modes. VEXTEC’s simulated Goodman technology differs from the existing OEM design methods, in that it considers the component geometry, vibratory mode along with the material microstructure variability to predict HCF limits.
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Abstract # 3
Submit Under “Fleet Management Practices”
Durability Analyses, Life Prediction, and Life Cycle Cost: A Systematic Approach
VEXTEC successfully developed a comprehensive diagnostic and prognostic system that will allow the Army to build and sustain the fighting force of tomorrow. The VEXTEC system directly enables valuable insights into vehicle reliability and the related costs of sustainment, thus providing for a more battle-ready fleet with a reduced life cycle cost.
By using existing vehicle performance data, VEXTEC’s methods will predict component, mission, and fleet reliability over time. Considering the sheer size of the Army’s fleet of vehicles, deploying the VEXTEC system reliability software fleet-wide could cut life cycle costs by billions of dollars annually while increasing in-service availability.
Products are composites of many component elements all stitched together to create a final overall product. The reliability of the final system is a function of the reliability of all of the components, including inter-relationship among them. If component reliability is sufficiently understood, it becomes possible to mathematically model the contributions to overall system reliability from each of the lower level elements. This has been the core methodology VEXTEC developed. Design is an iterative process. It can optimize product reliability while considering physical, performance and cost constraints. If the cost, performance and reliability sensitivities of the design can be determined, the effect of a set of design changes on life cycle cost can be estimated. VEXTEC’s system reliability methods thus provide the necessary tools, analysis capability, and information required to cost effectively maintain and sustain the in-service availability of the fighting force of today’s and tomorrow’s Army. |
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