Residual Strength Determination
Residual strength is the load or cycles (usually mechanical) that a damaged structure
or material can still carry without failing. This type of analysis requires an understanding
of damage state in a given structure. The damage can be caused by in-service loading, such as
introduction of micro-cracks in a composite panel, or damage and delamination in a panel when
subjected to impact loading. The capability is critical for aerospace and infrastructure
applications where post damage response is of great importance. For example, when fatigue causes
a crack in an aircraft panel to grow in flight, residual strength analysis is crucial to determine
how many more cycles can the aircraft sustain for safe landing assessment. Another example,
what is the reduction in compressive strength of a stiffened panel after the panel is subjected
to low velocity impact. Integrated computational simulation such as the one developed by AlphaSTAR,
can be used to determine post damage reduction ins residual strength.
Provide analysts and designers with accurate computational simulation capability to
determine residual strength following a specific damage event (example: tension after impact
TAI, compression after impact CAI and shear after impact SAI, residual strength after discrete
source damage in a stiffened panel of wing).
Use GENOA's multi-scale progressive failure analysis MS-PFA to determine all stages
of damage evolution under service loading. Damage evolution comprises damage initiation and
propagation (including delamination). MS-PFA is finite element based progressive failure analysis
that augments traditional commercial FEA stress solvers for durability and damage tolerance.
It allows the extraction of damage history for use in post-damage residual strength calculation.
Relevant GENOA modules are MS-PFA: static, fatigue, and impact (explicit). For example,
low or high cycle fatigue analysis for a given number of cycles, then damage history is extracted
from fatigue analysis for use in determining maxim static failure load (as typically done for
aircraft panels or wing component).
Determine damage history under service loading.
Determine post damage residual strength including failure modes and failure location)
Answer what can be done to improve residual strength post damage
Evaluate and manage risk associated with certain damage events
Technology was applied successfully to determine post impact residual strength
on coupon and element, and component level structures made polymer composites. Furthermore,
it was applied to determine residual strength on wing structures after fatigue.