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US 10,095,818 B2Granted
Strength prediction system and method for composite laminates
AssigneeThe Boeing Company
InventorsMostafa Rassaian, Jonathan H. Gosse, Andrew E. Parrish, Michael J. Graves
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Abstract
A method of predicting the strength characteristics of a composite laminate may include loading a structural model of a composite laminate formed of a material system. The method may additionally include comparing strain invariants from loading the composite laminate to critical strain invariant values of the material system. The method may also include identifying as a first significant event (FSE) a strain invariant of the matrix and/or the fibers reaching a critical strain invariant value.
Claims22
A method of predicting strength characteristics of a composite laminate containing fibers embedded in a matrix, comprising the steps of:
- loading a structural model of a composite laminate with one or more design loads, the composite laminate formed of a material system and having a ply layup of plies arranged in a ply stacking sequence;
- comparing strain invariants from loading the structural model of the composite laminate to critical strain invariant values of the material system;
- determining, if an applied matrix strain reaches a critical matrix dilatation strain, whether fibers can fail by comparing a fiber axial strain to a fiber principal strain, the fiber axial strain oriented parallel to a fiber axis, the fiber principal strain oriented normal to the fiber axis;
- loading, if the fibers can fail, the structural model until at least one ply reaches a critical fiber distortion strain and determining whether the fibers in the plies are in tension or compression and whether the fibers can fail;
- calculating, if the composite laminate contains fibers in compression that can fail and fibers in tension that can fail, a first significant event (FSE) as an amplified strain, the amplified strain representing a failure strength of the composite laminate in an undamaged condition, the amplified strain being based upon a combined strain amplification number that is a function of critical fiber strain invariant values and is unique to one of the following failure sub-states:
- the compression fibers fail before any tension fibers fail;
- the tension and compression fibers fail simultaneously;
- the tension fibers fail before any compression fibers fail;
- wherein the FSE is a localized deformation of the composite laminate leading to a cascading series of material failures resulting in structural failure of the composite laminate, the FSE representing an analyzed strength of the composite laminate;
- iteratively adjusting the ply layup of the composite laminate until converging on a ply stacking sequence for which the analyzed strength representing the FSE of the composite laminate allows the composite laminate to support the one or more design loads without structural failure of the composite laminate;
- and
- constructing a composite laminate having the ply stacking sequence.
9 more elements
A method of predicting strength characteristics of a composite laminate containing fibers embedded in a matrix, comprising the steps of:
- loading a finite element model of a composite laminate with one or more design loads until an applied matrix strain reaches either a critical matrix distortion strain or a critical matrix dilatation strain, the composite laminate having a ply layup of plies arranged in a ply stacking sequence;
- determining whether fibers in the composite laminate can fail when the applied matrix strain reaches the critical matrix dilatation strain by comparing a fiber axial strain to a fiber principal strain, the fiber axial strain oriented parallel to a fiber axis, the fiber principal strain oriented normal to the fiber axis;
- loading, if the fibers can fail, the finite element model until at least one ply reaches a critical fiber distortion strain and determining whether the fibers in each ply are in tension or compression and whether the fibers can fail;
- calculating, if the composite laminate contains fibers in compression that can fail and fibers in tension that can fail, a first significant event (FSE) as an amplified strain, the amplified strain representing a failure strength of the composite laminate in an undamaged condition, the amplified strain being based upon a combined strain amplification number that is a function of critical fiber strain invariant values and is unique to one of the following failure sub-states:
- the compression fibers fail before any tension fibers fail;
- the tension and compression fibers fail simultaneously;
- the tension fibers fail before any compression fibers fail;
- wherein the FSE is a localized deformation of the composite laminate leading to a cascading series of material failures resulting in structural failure of the composite laminate, the FSE representing an analyzed strength of the composite laminate;
- iteratively adjusting the ply layup of the composite laminate until converging on a ply stacking sequence for which the analyzed strength representing the FSE of the composite laminate allows the composite laminate to support the one or more design loads without structural failure of the composite laminate;
- and
- constructing a composite laminate having the ply stacking sequence.
8 more elements
Dependencies are inferred from the claim text.