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1、Lesson content:Introduction Laminated Shell Section DefinitionLaminated Solid Section DefinitionSection Point Based Postprocessing TechniqueAppendix 4: Alternative Modeling Techniques60 minutesIntroductionAs alternative modeling techniques for composites,Shell sections can be used to define a lamina

2、ted conventional shell made of one or more materials. Shell sections can also be used to model stacked continuum shell elements.Similarly, solid sections can be used to define a laminated solid and to model stacked solid elements.Section point based postprocessing can be applied to view contour plot

3、s of integration point values, material orientations, and output from reinforcement (rebar) layers in the shell. Consistent Abaqus/CAE and keywords interfaces are provided. Laminated Shell Section Definition (1/10)Shell section definitionA shell section can be defined with:*SHELL SECTIONemploys nume

4、rical integration during the analysis for use with nonlinear materials.*SHELL GENERAL SECTIONpre-integrates the section for use with linear materials.2121Laminated Shell Section Definition (2/10)Both section options support multilayer composite shells.The section can have any number of layers with i

5、ndependent orientation and independent material in each layer. *SHELL SECTION, COMPOSITE*SHELL GENERAL SECTION, COMPOSITELaminated Shell Section Definition (3/10)The SHELL SECTION, COMPOSITE option defines for each ply: Section pointsMaterial definitionMaterial orientationThickness Ply nameSimpsons

6、rule is used for section stiffness integration. In general this option is used when nonlinear material response must be modeled.Include the SYMMETRIC parameter to activate simplified modeling of symmetric composites.Laminated Shell Section Definition (4/10)The SHELL GENERAL SECTION option provides s

7、ignificant computational savings if the material behavior is linear. In this case the section stiffness matrix can be given directly:Laminated Shell Section Definition (5/10)Alternatively (and more commonly), the section is defined by giving the layers thicknesses and material properties for layers.

8、Abaqus will then calculate the sections behavior automatically.You can specify the idealization of the section response and the symmetric composites.In this case (as with the *SHELL SECTION option) stress and strain output is available throughout the shells thickness.Usage:*SHELL GENERAL SECTION, CO

9、MPOSITE, SYMMETRIC, MEMBRANE ONLY|BENDING ONLY|SMEAR ALL LAYERSLaminated Shell Section Definition (6/10)The shell section properties given through the *SHELL GENERAL SECTION option can be also defined via user subroutine UGENS. This approach is particularly useful if the section response involves bo

10、th geometric and material nonlinearity, such as may occur during section collapse.Usage: *SHELL GENERAL SECTION, USERLaminated Shell Section Definition (7/10)Example of thin laminated shell analysisFrom Laminated Composite Shells: Buckling of a Cylindrical Panel with a Circular Hole, Abaqus Example

11、Problems Guide, Section 1.2.2.Laminated Shell Section Definition (8/10)ResultsBuckling modes, element types S4R5, S9R5, and STR165Laminated Shell Section Definition (9/10)In this case delamination causes the shell to collapse suddenly (catastrophic failure). The finite element models predict only th

12、e structural failure there is no modeling of the delaminationand so fail to indicate the severity of the event. Examining the values of TSHR13 and TSHR23 at the collapse load might alert the analyst to this possibility.Composite panel: load-displacement responseLaminated Shell Section Definition (10

13、/10)Represents the current snapshot of the deformed shape as shown on the left side.Delta/LP/EADelta/LP/EADelta/LP/EADelta/LP/EAPostbuckling deformations: 10% h imperfection with S4R5Linear bulking loadLinear bulking loadLinear bulking loadLinear bulking loadNote: 10% is a very large initial imperfe

14、ction, and much smaller values are typically used. In this case 10% is specified for demonstration purposes.Laminated Solid Section Definition (1/6)Solid section definitionA solid section can be defined with:This section option supports multilayer composite solids: The section can have any number of

15、 layers with independent orientations and different materials in each layer.*SOLID SECTION, COMPOSITE, SYMMETRICto activate simplified modeling of symmetric composites*SOLID SECTIONLaminated Solid Section Definition (2/6)Example of laminated solid analysisFrom Thick composite cylinder subjected to i

16、nternal pressure, Abaqus Benchmarks Guide, Section 1.1.4.Geometry of laminated cylinderLaminated Solid Section Definition (3/6)In this model the cylinder is discretized with two C3D20R elements (of different sizes) in the radial direction.innerouterassign to the set innerassign to the set outerLamin

17、ated Solid Section Definition (4/6)The results are compared with the analytical solution.Normalized radial displacement Normalized displacementAnalytical solutionAbaqusRadial directionLaminated Solid Section Definition (5/6)Circumferential stressRadial directionNormalized stressAnalytical solutionAb

18、aqusLaminated Solid Section Definition (6/6)Radial stress The radial stress, especially near the inside of the cylinder, is not accurate due to the coarse mesh through the thickness. A refined mesh is required for an accurate result.Normalized stressAnalytical solutionAbaqusRadial directionSection P

19、oint Based Postprocessing Technique (1/4)As an alternative postprocessing technique, section point based postprocessing is available to visualize results.Selecting section point data by category is used to control the section points from which Abaqus obtains integration point results and material or

20、ientations.Reinforcement (rebar) layers in membrane, shell, composite solid, and surface elements are treated as section points for output purposes.Note: Details of reinforcement (rebar) layers will be discussed in Lecture 5, “Reinforcement Modeling.”Section Point Based Postprocessing Technique (2/4

21、)In many cases the location of a section point is described in terms of its position relative to the midpoint of the cross section.For shells and composite solids this relative position is reported as a fraction of the distance between the midpoint of the cross section and the SPOS or SNEG surface o

22、f the section. Reinforcement layers are indicated by their unique name. Contours of integration point values can be plotted as two-dimensional fronts located at the section points.Contours can be plotted for two section locations on the same shell (conventional or continuum) or composite solid.Section Point Base