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The Science of
Damage Tolerance is a multidisciplinary subject, involving a
combination of fatigue and fracture of metallic and polymeric
materials, structure and component design, manufacturing quality,
damage detection and monitoring systems and structural reliability.
HLA’s experience includes all of the above disciplines including
loads, materials, computational procedures, structural analysis,
stress analysis, and fatigue and fracture Mechanics analyses. Using a
combination of these disciplines and related software, HLA has
performed complex fatigue life predictions and fracture mechanics
characterizations to evaluate structural integrity of commercial
structures.
HLA Engineers, Inc. has several years of experience in various areas
of Damage Tolerance Assessment, Fatigue and Fracture Mechanics. We
have participated in several Government Programs and Industrial
Studies of Fatigue, Fracture Analysis and Durabilitity and Damage
Tolerance Analyses in the Aircraft and Railroad Industries. Our
extensive background in Structural Analysis, FEA and Material
Behaviour and Characterization gives us a unique combination of
analytical and experimental capabilities that can be applied for
diverse problems in failure analysis.
Our Experience includes:
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FEA of structures
using commercial finite element programs like ANSYS, NASTRAN and
MARC with linear and nonlinear elasticity and plasticity.
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Thermal and
Structural vibration and Stress Analyses.
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Fracture mechanics
including residual strength of cracked components, crack growth,
arrest and damage tolerance.
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Railroad Tank and
Freight Cars, Fatigue in Railroad Structures, Construction
Materials, Fatigue in Pressure Vessels, ASME Pressure Vessel and
Boiler Codes.
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Fatigue in
Aircraft and Helicopter Structures, Advanced composites, Design of
composites, Polymers and Elastomers, Adhesives, Joining and
Interlaminar Fracture, Fatigue of Polymers, Polymer matrix
composites, matrix cracking and fiber failure.
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S-N Curves,
Endurance Limits and Fatigue Strength Evaluation, Mean Stress
Effects, Goodman & Haigh Diagrams.
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Low-cycle Fatigue,
Neuber Notch Strain Analysis, Cumulative Damage Acumulation and
MINER'S Rule and Its Applicability.
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Fracture Toughness
— Thickness & Directionality Effects, Residual Strength, Creep &
Thermal Fatigue, Radiation.
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Crack Initiation
and Propagation, crack arrest and multiple load paths studies,
Paris, Forman, & Walker equations, crack growth calculations,
variable amplitude loading, retardation, Willenborg, Wheeler, and
closure models, multiaxial loadings — mixed mode crack problems,
progressive cracking and damage models, cracking at structural
holes, loaded and unloaded structural holes, structural failure
modes: creep, fatigue, and corrosion cracking etc.
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Load spectrum
analysis, sequence effects, truncation, clipping and retardation
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NASA FLAGRO and
NASGRO crack growth computer programs.
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Establishing
structural inspection intervals, POD analysis, Weibull analysis for
reliability.
HLA can provide state-of-the-art design, analysis, testing and
computation capabilities, in DTA. We have worked extensively and can
partner with Research Organizations and Universities in identifying
practical efficient and cost effective methods of evaluating Durability
and Damage tolerance of structures.
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