abaqus经典声学分析例题l7-adiabatic-analysis

1、Adiabatic AnalysisLecture 7Copyright 2006 ABAQUS, Inc.L7.2OverviewAdiabatic AnalysisAdiabatic Analysis ExampleHeat Transfer and Thermal-Stress Analysis with ABAQUSCopyright 2006 ABAQUS, Inc.Adiabatic AnalysisCopyright 2006 ABAQUS, Inc.L7.4Adiabatic AnalysisAdiabatic analysis can be used in cases whe

2、re inelastic deformation of a material causes heating, yet the event is so rapid there is no time for heat to conduct in the material.The analysis is called “adiabatic” because each material point is treated as though it is perfectly insulated from its surroundingsall heat generated at the point sta

3、ys at the point.Typical examples are very rapid accident conditions or high-speedforming processes.Forging and extrusion are two examples: thermal generation goes entirely to local heatingHeat Transfer and Thermal-Stress Analysis with ABAQUSCopyright 2006 ABAQUS, Inc.L7.5Adiabatic AnalysisWhen to pe

4、rform an adiabatic analysisA guideline for determining whether a given event is occurring fast enough for the adiabatic assumption to be valid is shown:densityspecific heat rc Dl2typical element dimension of an element with plastic dissipationtApproximate time it takes for heat to conduct across an

5、element boundarytotal6kconductivityIf the time period of the process is on the order of the time it takes for heat to flow across a single element, consider modeling the process as an adiabatic analysis.Heat Transfer and Thermal-Stress Analysis with ABAQUSCopyright 2006 ABAQUS, Inc.L7.6Adiabatic Ana

6、lysisFor a mesh with elements 1 mm long, the time it takes for heat to conduct across one element is:(1)Multiply by length2 for different element sizeSource: Table B, Schaums Outline of Heat Transfer, 1977.Heat Transfer and Thermal-Stress Analysis with ABAQUSCopyright 2006 ABAQUS, Inc.Materialam2/s

7、x 105t1 mm (1)sSilver17.0.0010Copper11.4.0015Carbon steel1.27.013Stainless0.387.044Marble0.139.12Rubber0.0082.1Pine0.0082.1Still water0.0141.2Still air2.21.008L7.7Adiabatic AnalysisAdiabatic thermal stress analysis is available for elastic-plastic materials (with or without rate-dependent properties

8、) being analyzed with either*STATIC or *DYNAMIC analysis procedures.Required material options are:*ELASTIC*PLASTIC*INELASTIC HEAT FRACTION*DENSITY*SPECIFIC HEATOptional material behavior may include:*RATE DEPENDENT*LATENT HEATHeat Transfer and Thermal-Stress Analysis with ABAQUSCopyright 2006 ABAQUS

9、, Inc.Adiabatic Analysis ExampleCopyright 2006 ABAQUS, Inc.L7.9Adiabatic Analysis ExampleReference: Example Problem 1.3.16, Upsetting of a cylindrical billet: coupled temperature-displacement and adiabatic analysis.Youngs modulus = 200 GPa Poissons ratio = 0.3Thermal expansion =1.2E-5 / oC Initial s

10、tatic yield stress, so= 700 MPa Work hardening rate = 300 MPaportion modeledStrain rate dependence:30 mme= D (ss- 1)p; D = 40pl0p = 5s,Specific heat = 586 J/(kg oC) Density = 7833 kg/m3Conductivity = 52 J/(m-s-oC)y20 mmCylindrical billetxHeat Transfer and Thermal-Stress Analysis with ABAQUSCopyright

11、 2006 ABAQUS, Inc.L7.10Adiabatic Analysis ExampleDeformed shapeHeat Transfer and Thermal-Stress Analysis with ABAQUSCopyright 2006 ABAQUS, Inc.L7.11Adiabatic Analysis ExampleComparison of adiabatic and fully coupled modelsThe upsetting is formed very quickly (0.1 sec).The only differences between th

12、e ABAQUS models for the adiabatic analysis and those for the fully coupled analysis are:Element type CAX8R has been substituted for CAX8RT, and the procedure type is*STATIC, ADIABATIC1.5E-3, 0.1, 5.E-11, 5.E-3while for fully coupled analysis,*COUPLED TEMPERATURE DISPLACEMENT, DELTMX=100.1.5E-3, 0.1, 5.E-11, 5.E-3is used.Heat Transfer and Thermal-Stress Analysis with ABAQUSCopyright 2006 ABAQUS, Inc.L7.12Adiabatic Analysis Examp