The Boeing Company

Mostafa Rassaian

Jonathan Henry Gosse

David W Twigg

Vladimir Balabanov

Yuan-Jye Wu

Stephen Christensen

Olaf Weckner

Simon D Senibi

Kenneth Joseph Hunziker

Eric Y Chan

Jeong-Beom Ihn

Marc Joel Piehl

Hong Hue Tat

Omid B Nakhjavani

Lee Charles Firth

Tuan Nguyen

James Johnathan Childress

David Mitchell Anderson

Peter S Guard

Shahriar Khosravani

Paul E Mikulencak

David L Banks

William John Koch, Iv

Forouzan Behzadpour

Adriana Willempje Blom

Joshua M Montgomery

Akif O Bolukbasi

Thomas A Grandine

Shawn M Pare

Jung-Chuan Lee

Thomas T Arakawa

Mohammad Ali Heidari

Matthew Todd Grimshaw

Mark W Beranek

James Frederick Ackermann

Michael Jeffrey Graves

Gerould K Young

Josh M Montgomery

Jaffar Sher Iqbal

Michael Andrew Epton

Anthony K Gilbert

Evin J Cramer

Richard William Brigman

Mark A Stadum

Matthew Steven Patterson

Leo E Dondlinger

Jeffery S Knowlton

Richard N Huizenga

Gilbert L Lewis

Zachary Robert Meves

Jeffery L Waugh

Thomas R Baxter

Kevin R Davis

Jenna Kristin Pang

Jeffrey Ko

Boris B Sokolov

Jeffrey S Knowlton

Alan Edqar Landmann

Jung-Chaun Lee

Abdelhai Maysara Saadi

Andrew E Parrish

Mark Voitek

David Gastellum

Terry N Christenson

A computer is configured to enable a rapid, consistent, ply-by-ply, quantitative analytical assessment of various Finite Element Method (FEM) material models based on metrics defined for impact damage. Additionally, the computer is configured to provide a method for determining the accuracy of such FEM material model(s) by comparing the output of those models to non-destructive evaluation (NDE) test data.

Composite ply-by-ply damage assessment using correlation factors between finite element models (FEMs) and non-destructive evaluations (NDEs)

A system comprises a model generation system and an analyzer. The model generation system is configured to modify a model of a laminated composite structure to meet a user defined objective and to meet at least one of user defined performance constraints or user defined manufacturing constraints by changing at least one ply characteristic of at least one ply of the model while maintaining ply boundary geometry constraints for each ply of the model. The ply boundary geometry constraints of the model generation system include a number of defined ply boundary geometries each described by a respective mathematical function. The analyzer is configured to return objective values or constraint function values for at least one ply of the model.

Controlling and adjusting ply shapes of laminated composite structures for performance and manufacturing considerations

A composite structure, such as a laminated composite panel, for example, comprises one or more layers or 'plies' embedded in a matrix material or otherwise fixed together in an arrangement, commonly referred to as a 'stack up.' Each material in the structure has a corresponding material failure model (MFM) defining the physical characteristics of that material. A ballistic threshold velocity computing device obtains the MFMs for each material in the composite structure, generates a predicted ballistic velocity threshold velocity for each MFM, and then generates a parametric model to compute a composite ballistic velocity threshold velocity for the composite structure.

Determining the ballistic threshold velocity for a composite structure using multiple failure models

A system for fabrication of an aerospace structure incorporates a mold having a surface and at least one unidirectional SFL head adapted to lay down a plurality of collimated tows in a predetermined laminated pattern on the mold surface to produce a fuselage skin. At least one cross plied laminate SFL head is adapted to lay down a cross plied laminate base interface on the fuselage skin to establish a lattice rib shape for each of a plurality of lattice ribs. The cross plied laminate SFL head has a band placement head steerable to avoid structural design features and to maintain spacing from adjacent steered lattice ribs. The unidirectional SFL head is further adapted to lay down a plurality of collimated tows on the base interface of each of the plurality of lattice ribs for a first plurality of unidirectional tow plies in each lattice rib. The unidirectional SFL head has a fiber placement head steerable to match the lattice rib shape to avoid structural design features and to maintain spacing from adjacent steered lattice ribs.

Method and apparatus for fabrication of lattice composite fuselage for commercial aircraft employing steered fiber lay up

A method of analyzing the durability of a structure. Load-controlled testing is performed on samples of a composite material of the structure to relate critical strain invariants of the material to cyclic rates of strain invariant accumulation and frequencies associated with the cyclic rates. The material is characterized based on effective properties of the material, including the cyclic rates of strain invariant accumulation. Laminate properties and a geometrical definition of the structure are used to obtain a parametric model. Material characterizations are used to determine model element frequency responses to applied load conditions. Each element's frequency responses and critical strain invariants are used to determine whether damage is indicated at the element. Progression of damage is tracked and accounted for in the model.

Analyzing structural durability in the frequency domain

Composite skin-stringer structures which reduce or eliminate the risk of delamination at the skin-stringer interface. This can be accomplished by arranging ply directions (i.e., the angles of the fiber paths of the ply) in a layup in a way such that for the dominant loading, the skin and stringer will each deform in a way that reduces relative opening (fracture Mode I) and/or sliding (fracture Mode II) and/or scissoring (fracture Mode III) at the skin-stringer interface. This is possible when coupling between specific deformations modes is purposefully activated instead of being suppressed. The ply directions in the stringer are adjusted so that the stringer deforms in a controlled fashion to suppress or 'close' cracks that are about to form&#x2014;before the undesirable modes of failure form&#x2014;as load is applied.

Skin-stringer design for composite wings

A design process that uses lamination parameter inversion to generate a set of baseline layups having desired stiffness properties. Then the underdetermined Newton's method can be applied to explore solution manifolds describing alternative designs having similar if not identical stiffness properties. The manifold of solutions can be methodically examined to find those with desirable properties. Desirable properties include those that have been traditionally captured by design rules or those that improve manufacturability. Combining lamination parameters as design variables with lamination parameter inversion provides an efficient optimization process for non-traditional laminates.

Lamination parameter-based method for optimal design and manufacturing options

A method of generating an optimized design model for a composite laminate may include computing a normalized set of lamination parameters and laminate stiffness matrices of an initial laminate design, and determining, using an optimizer operating on a finite element model, optimum values for the lamination parameters and the laminate thickness. The method may further include adjusting the optimum value of the laminate thickness, and performing an inversion process extracting multiple solutions from the lamination parameters, each solution including a unique set of individual fiber angles for each ply and representing an optimized design model of the composite laminate.

System and method for designing composite laminates using lamination parameters

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.

Strength prediction system and method for composite laminates

A system and method for creating an optimized composite laminate structure containing a plurality of plies. The system has a processor and a memory, including an application interface. The application interface, when executed by the processor, is configured to operably: receive an input file having one or more of a maximum number of plies, design variables, material properties, and design constraints; determine an initial layup sequence defining parameters of a fiber orientation angle for each ply, and a total percentage of plies at a given fiber orientation angle; iteratively adjust the parameters, until an optimum set of parameters is obtained that achieves one or more predetermined margins of safety, and that achieves optimization of the composite laminate structure; and generate an output file for creating a layup, according to the parameters. The system further has a layup system for creating the optimized composite laminate structure.

System and method for optimizing composite laminate structures

Methods and systems for reducing finite element simulation time for acoustic response analysis are disclosed. In one embodiment, a method includes analytically creating a finite element model, the finite element model including a plurality of subdivisions. A plurality of cross-correlations between respective pairings of the subdivisions is then specified. A portion of the cross-correlations are then eliminated to provide a reduced set of cross-correlations between respective pairings of the subdivisions. The elimination includes determining a spatial distance value between at least two subdivisions, and discarding at least one of the cross-correlations for which the spatial distance value is greater than a specified threshold value. The finite element simulation is then performed using the reduced set of cross-correlations.

Reducing finite element simulation time by reducing cross-correlation terms

A method, apparatus, and computer program product are present for creating a composite structure. A number of characteristics for a number of components for the composite structure is obtained from a simulation of the composite structure using a model of the composite structure. A number of changes in the number of characteristics needed to meet a desired level of performance for the number of characteristics is ascertained. A number of attributes for a number of composite materials used to form the number of components corresponding to the number of characteristics having the number of changes is identified. The number of attributes for the number of composite materials for the number of characteristics having the number of changes based on the desired level of performance is changed.

Multi-scale modeling of composite structures

A computational optimization process uses the variable stiffness performance of composite laminates attributed to steered fiber to guide the design of stream functions describing the fibers to build it. This design process combines a finite element-based analysis tool, failure criteria and geometry optimization to determine steered angles associated with stream functions by an optimization program to meet target performance requirements, e.g., load condition(s), and failure criteria for quasi-static or dynamic events. The fiber angle distribution and thickness buildup are computed based on the stream function. The simulated structure is analyzed using finite element analysis. The disclosed process allows the designer to impose manufacturing constraints such as fiber steering radius.

Curved fiber paths for composite laminates

A system comprises an automated fiber placement (AFP) machine and a layup mandrel tool supported by the AFP machine. The mandrel tool includes a truss core and a plurality of mandrel panels attached to the truss core to form a layup surface.

Automated fiber placement including layup mandrel tool

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Bellevue, WA, United States of America

Mostafa Rassaian