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MSC Nastran

Multidisciplinary Structural Analysis

MSC Nastran is a high performance computing enabled structural analysis application used by engineers to perform static, dynamic, and thermal analysis across the linear and nonlinear domains, complemented with automated optimization and award winning embedded fatigue analysis technologies.

From the high performance computing capability to the high degree of certainty it delivers, MSC Nastran is engineered to give you a heightened awareness of how your products will behave.

  • Accurately and quickly predict complex product behavior.
  • Find design conflicts early in the design cycle.
  • Reduce the number of design changes.
  • Make trade off studies for performance and reliability.

Capabilities:

Predict Product Life, Optimize Designs

 

Given the large costs associated with product recalls and warranties, fatigue analysis is a critical part of product development. Large investments are continuously made to give engineers better insight into fatigue related behavior early in the product development process.

Most fatigue life predictions involve a significant amount of time and effort to perform, due in part to a fragmented solution procedure, but MSC Nastran features a new embedded fatigue capability that delivers fatigue life results faster.

In one example of an automotive wheel carrier, the common fatigue approach took 8 hours and 11 minutes, but with MSC Nastran Embedded Fatigue, the process took 38 minutes. That is a 12x speed up.

In addition, MSC Nastran’s optimization technologies can be used to maximize product performance, i.e. minimize product weight while meeting fatigue life targets. In one case, optimization led to design changes resulting in a mass savings of 13% and an increase of life from 105 to 108 cycles.

MSC Nastran Embedded Fatigue capabilities include:

  • Stress-Life
  • Strain-Life
  • Factor of Safety (FOS) analysis (both S-N & E-N)
  • Multi axial responses processed using Critical Plane method
  • Parallel Processing (up to 100 threads)
  • Utilities Tools
  • Multiple Fatigue Analysis can be performed in a single job submittal

Advanced Nonlinear Capabilities

 

For a better prediction of product behavior, engineers go beyond the linear domain by performing nonlinear analysis. Nonlinear analysis is significantly more complex that linear analysis and usually not available in other FEA solvers. MSC Nastran includes nonlinear capabilities that enable engineers to:

  • Extend the value of linear FE models by reusing the same finite element (FE) model for nonlinear analysis.
  • Perform system level analysis by studying the behavior of contacting parts and associated load transfer
  • Avoid interferences between adjacent components in assemblies
  • Use simple contact body definitions for systems composed of numerous components.
  • Chain analysis disciplines together for multiple event simulations.
  • Simulate highly dynamic events.
  • Study the interaction between the structure and surrounding fluid with FSI technology.
  • Couple analyses where thermal and structural results affect each another.
  • Represent the characteristics of numerous nonlinear materials.
  • Go beyond first ply failure in advanced composites by performing progressive ply failure on composite laminates.

Develop High Performance Composites

 

To continuously reduce the weight of structural designs, MSC Nastran offers numerous capabilities that provide a wealth of insight into the complex behavior of composite structures. With MSC Nastran, engineers can:

  • Simulate across static and dynamic analysis domains for preliminary or detailed designs.
  • Perform high-fidelity modeling with a collection of efficient finite elements specially tuned for advanced composites.
  • Reduce subcomponent testing by predicting damage trajectories within composite laminates with MSC Nastran’s delamination capabilities.
  • Improve the damage-tolerance characteristics of your composite structures by going beyond first ply failure and performing progressive ply failure analyses.
  • Reduce weight while improving structural performance with built in optimization tools that enable you to optimize across multiple designs and analysis disciplines simultaneously.
  • Study the complex behavior of composite designs subjected to rapid loading. 

 

Effectively study the dynamic response of your structural designs

  When it comes to modeling and analyzing large systems for vibration, MSC Nastran is the best and most efficient solution available. Key capabilities enable engineers to:
  • Select from wide selection of eigenvalue extractors and efficiently determine the normal modes of undamped and damped structures.
  • Review structural responses caused by frequency and transient based loadings.
  • Monitor the load paths or energy flows through a structure with Transfer Path Analysis (TPA). 
  • Utilize Automated Component Mode Synthesis to quickly solve large-scale dynamic and acoustic problems.
  • Understand out of balance systems, determine system stability, detect imminent product failure, and calculate safe operating ranges for structures with the dynamics of rotating components.
  • Conveniently share design models and preserve proprietary information by utilizing external superelements.
  • Perform interior and exterior acoustic analysis with capabilities such as participation factor analysis, trimmed material analysis, element sensitivities, weakly coupled acoustics, and more.

Engineered for High Performance Computing

 

MSC Nastran is rapidly moving forward and taking advantage of the latest HPC advancements and hardware. With MSC Nastran:

  • Quickly obtain results for large modal based analyses and NVH studies with Automated Component Modal Synthesis.
  • Accelerate simulations by including GPU hardware as part of your HPC resources.
  • Take advantage of the latest parallelization techniques for multi processor systems in small to large clusters.
  • Efficiently analyze key structure sections with Automated Superelements.

 

Competitively Optimize Product Performance

 

Developing the best performing products is a common objective held by every engineer, but achieving this objective is not simple when multiple design variables, constraints, and objectives must be considered. MSC Nastran helps achieve this objective by offering numerous optimization capabilities that actively search for the best design given a design space. Use MSC Nastran to:

  • Simultaneously optimize multiple designs across multiple analysis domains with Multi Model Optimization.
  • Determine efficient material distributions for critical load paths, without compromising strength and stiffness, with MSC Nastran’s Shape and Topology Optimization.
  • Enhance the performance of beaded flat sheets with topography Optimization.
  • Find the best thicknesses distribution for thin structural designs with MSC Nastran’ Topometry/free-size Optimization..
  • Combine MSC Nastran’s optimization capabilities and effectively reduce the weight of composite laminates.

 

Simulate across multiple analysis disciplines

 

Rarely does a structure have to conform to design criteria from a single discipline. To obtain an effective design, multiple factors and often multiple disciplines need to be accounted for. The multiple disciplines could be as simple as a linear static analysis, a frequency response study, or as complex as accounting for loads from a multibody dynamic analysis for a automobile safety study. A multiple discipline analysis can also be an implicit nonlinear analysis on a pre-stressed structure followed by an impact study using explicit analysis which may still be followed by implicit analysis for any residual stresses.

Analysts often have to use multiple, incompatible tools to solve these various aspects of the design. MSC Nastran provides all of these disciplines in one environment and tightly integrates them, enabling engineers to accurately represent the behavior of their structures.

Multiphysics Simulation

 

Product development teams need to verify and optimize designs subjected to diverse events,  such as thermal or fluid loadings. An understanding of how thermal history or thermal state affects structural behavior, how vehicle trims influence cabin acoustistics, or how flow induced stresses or deformation affect a system’s behavior.

MSC Nastran supports a chained, uncoupled or coupled approach, giving flexibility to include the influence of multiple physical phenomena of your designs. Scalability of MSC Nastran also enables you to conduct entire structure studies without sacrificing accuracy. Typical examples of multiphysics scenarios include:

  • Brake squeal analysis
  • Fluid filled bottles
  • Hydroplanning
  • Brake heating
  • Plastic heat generation during forming

Aeroelasticity I for Static and Dynamic Aeroelasticity and Aeroelastic Flutter

   

Aeroelastic analysis is a critical aspect of aircraft design.  MSC Nastran Aeroelasticity I enables users to perform static and dynamic aeroelasticity analysis, as well as aeroelastic flutter analysis, in order to obtain necessary design and certification data.

Static Aeroelasticity

The structural load distribution on an elastic vehicle in trimmed flight is determined by solving the equations for static equilibrium. The solution process leads to aerodynamic stability derivatives, for example, lift and moment curve slopes and lift and moment coefficients due to control surface rotation, and trim variables, for example, angle of attack and control surface setting, as well as aerodynamic and structural loads, structural deflections, and element stresses. The analysis at subsonic speeds utilizes the Vortex-Lattice aerodynamic theory (that is, the steady case of the Doublet-Lattice method); the analysis at supersonic speeds uses the ZONA51* aerodynamic theory at zero reduced frequency. Control surface reversal speeds can be obtained by interpolation of roll control effectiveness, Cl, versus flight dynamic pressure. Static aeroelastic divergence speeds may be determined by the K- or KE-methods of flutter analysis at very low reduced frequency or from the PK-method of flutter analysis.

The static aeroelastic capability provides the following capabilities:

  • The user supplies finite element models for the definition of the structure and aerodynamic loading, including information on the flight condition. The loads and accelerations are assumed to be independent of time that is, quasi-steady.
  • Stability and control derivatives are produced for each unique flight condition (Mach number and dynamic pressure). Derivatives are produced for the rigid vehicle and for the restrained and unrestrained elastic vehicles.
  • A trim analysis is performed that determines unknown trim values and then performs standard data recovery for each trim subcase defined. Aerodynamic forces and pressures on the aerodynamic elements may also be obtained.
  • Three options are available for altering the theoretically predicted aerodynamics.
    • Correction factors
    • Experimental pressures
    • Adjustments to the downwash to account for, for example, the effects of camber and twist
  • A static aeroelastic divergence analysis is available. The divergence analysis is performed at the Mach numbers specified.

Any of the aerodynamic methods can be utilized for divergence analysis. Strip Theory, the Mach Box method, and Piston Theory are not available for trim and stability analysis.

Dynamic Aeroelasticity

The dynamic aeroelasticity capability provides analysis in the time or frequency domain. The following capabilities are available:

  • The user supplies finite element models for the structure and the aerodynamics. Aerodynamic matrices, including gust loads, are computed at each of the user-specified Mach number and reduced frequency combinations.
  • Frequency or time-dependent loading can be specified. Time varying loads are converted to the frequency domain using ad hoc Fourier transform techniques. The excitation can be aerodynamic (such as gust loading), or external (such as mechanical loads representing store ejection or landing loads).
  • A modal analysis is always performed. Changes in the mass and stiffness matrices may be made subsequent to the modal analysis via customized input.
  • Control systems can be modeled using extra point, transfer function, and customized inputs. The user can supply downwash vectors for extra point motions.
  • Basic computations are always performed in the frequency domain. If input is provided in the time domain, an inverse Fourier transform is used to provide output in the time domain.
  • The modal participation type of data recovery is used. The internal loads or stresses are found in each mode and the response loads are found from the linear combination of the products of the loads in each mode and its amplitude. This method of internal load response calculation is called the “Modal Displacement Method” in Bisplinghoff, Ashley, and Halfman (1955, pp 641-650).
  • Output can be displacements (including velocities and accelerations), stresses, or constraint forces. XY-plots are available. Aerodynamic data (pressures and forces) are also available with frequency response analysis.
  • Random response analysis obtains power spectral density, root mean square response, and mean frequency of zero crossings.

All MSC Nastran aerodynamic theories are available for calculating the dynamic aeroelastic response to external loading. The Strip, Mach Box, and Piston Theory aerodynamics are not available for gust loads.

Flutter Analysis

The dynamic aeroelastic stability problem, flutter, is solved by any of three methods. The traditional American flutter method developed by the Air Materiel Command (AMC) in 1942 is available in the first two methods. The first method is called the K-method and is a variation of the AMC method; the second method, called the KE-method, is more efficient from the point of view of tracking roots, but is limited in input (no viscous damping) and output (no eigenvectors). The third method, called the PK-method, is similar to the British flutter method, which was developed by the Royal Aircraft Establishment.

The flutter analysis provides the following capabilities:

  • The user supplies finite element models for the definition of the structure and the aerodynamic model. Aerodynamic matrices are computed explicitly at each of the user-supplied Mach number and reduced frequency combinations.
  • A modal analysis is always performed. Changes in the mass and stiffness matrices may be made subsequent to the modal analysis.
  • Control systems can be modeled using extra point, transfer function and customized inputs. The user can supply downwash vectors for extra point motions.
  • A flutter analysis is performed based on the parameters specified. The K- and KE-methods compute flutter roots for user-specified values of density, Mach number and reduced frequency. The PK-method extracts these roots for user-specified values of density, Mach number and velocity.
  • Multiple subcases can be specified. This enables the use of, for example, different flutter solutions or multiple sets of customized inputs.
  • A flutter summary is created and (optionally) V-g and V-f plots are produced.
  • Data recovery can be performed on the flutter eigenvectors produced for the K- and PK-flutter solutions.

All MSC Nastran aerodynamic theories are available and more than one aerodynamic theory can be present in the same aerodynamic model.

Available Aerodynamic Theories

MSC Nastran has implemented seven internal aerodynamic theories:

  • Doublet-Lattice subsonic lifting surface theory (DLM)
  • ZONA51* supersonic lifting surface theory
  • Constant Pressure Method for supersonic lifting surface theory
  • Subsonic wing-body interference theory (DLM with slender bodies)
  • Mach Box method
  • Strip Theory
  • Piston Theory

Automated Optimization Enabled

The automated optimization capabilities of MSC Nastran make it possible to optimize the designs of vehicles for aeroelastic loads, flying qualities, and flutter, as well as for strength, vibration frequencies, and buckling characteristics.

To learn more:

*Access to ZONA51 is available through MSC Nastran Aeroelasticity II

Connectors for Rapid Assembly Modeling

 

Very few FEA solutions offer various ways of modeling structural connections and fasteners effectively and simply. Spot welds, seam welds, bolts, screws, and so on can be represented, depending on the modeling goals, either with flexible springs or bars, rigid elements, or multipoint constraints (MPC). Though general, these elements are sometimes difficult to use; singularities may be introduced particularly in the out-of-plane rotational direction for shell elements, rigid body invariance may not be assured, and data preparation and input can be a formidable task in real-world applications. Increasing mesh refinement can also introduce further stiffness errors; point-to-point connections in which effective cross-sectional areas are larger than 20% of the characteristic element lengths can often lead to significant underestimation of connector stiffness.

The MSC Nastran Connector elements address and solve such modeling issues. Connections can be established with ease between points, elements, patches, seam lines, dissimilar meshes, or any of their combinations. The connector elements are applicable to numerous scenarios and are easy to generate.

To learn more:

Automated Optimization for Improved Structural Performance

   

As structural designs become increasingly complex, optimizing such designs becomes an overwhelming challenge.

MSC Nastran Optimization makes available technologies that can automate the optimization process of FEA models to

  • Produce more efficient designs having maximum margins of safety.
  • Perform trade-off or feasibility studies.
  • Assist in design sensitivity studies.
  • Correlate test data and analysis results (model matching).

Size Optimization

Use size optimization to improve the performance of your designs by varying basic design parameters such as beam cross sectional dimensions, sheet thicknesses, composite ply orientations, material stiffness, material densities, and more. Achieve design objectives such as structural weight, displacements, stresses, etc.

Shape Optimization

Implement Shape Optimization to optimize the profile of your designs. Specific boundaries may be selected and allowed to vary during the optimization process.

Topometry Optimization

Utilize topometry optimization to identify critical design regions, locate where to add or remove material, or find optimal locations of spot welds. Topometry is a special type of size optimization where the optimization process occurs on an element-by-element basis, traditional size optimization considers large groups of elements as a whole.

Topography Optimization

Apply topography optimization to improve the performance of sheet metal parts. Topography optimization (also called bead or stamp optimization) allows users to generate optimal design alternatives for reinforcement bead patterns. Topography optimization is a special shape optimization process where finite element nodes are allowed to move and vary normal to the shell element surfaces or the user's given direction.

Topology Optimization

Take advantage of topology optimization to generate conceptual designs that target structural mass, eigenvalue, displacements, or other global design responses. Topology optimization operates in an element-by-element basis, where finite elements are either retained or omitted from the design.

The most common difficulties with comparable topology optimization solutions have been checkerboard effects, large number of small voids, introduction of numerous smaller members especially with mesh refinement, design proposals difficult to manufacture, and large computation costs with increasing variables. The topology optimization in MSC Nastran provides answers to each of these difficulties.

If manufacturability is of importance, a large number of manufacturing constraints are available to ensure manufacturability, such as symmetry constraints including cyclic symmetry, extrusion constraints for uniform thickness along draw direction, single and two die casting constraints for preventing cavities along die movement.

To learn more:

Multi Model Optimization for Improved Performance Across Structural Designs

   

Improving the performance of structural systems requires the simultaneous optimization of both individual components and assemblies, but traditional FEA solutions are limited to single optimization tasks, i.e. only one model may be optimized at a time.

MSC Nastran Multi Model Optimization allows the combination of two or more related optimization tasks into a single combined optimization task. Multiple models that differ in their topology or in their analyses type may be optimized concurrently, not individually and independent from one another. One scenario might be if different variants of an aircraft share a common wing design but have different fuselages (standard and stretch configurations). It would be difficult to design this with the standard optimization capabilities in most FEA solutions, but it is readily achievable with Multi Model Optimization. Another scenario is one where a detailed model of a component is available and can be used to match analysis data with test results. At the same time, a less detailed model of the same component is included in a global model that is being used to perform optimization with global constraints, such as flutter speed. Multi Model Optimization can be used in this case to perform both optimizations simultaneously and thereby maintain a common design.

To learn more:

Krylov Solver for Faster Direct Frequency Response Analysis

 

 

Direct frequency response analysis of damped dynamic systems can be very compute-intensive in standard FEA solutions, especially if the problem contains numerous damping elements and considers a large frequency range.

The Krylov Solver shortens the time to perform direct frequency response analysis in comparison to standard FEA solutions. The Krylov solver is significantly efficient with solid models with small modal density and has been found to reduce solution times by up to a factor of 100. Faster solution times allows the specification of smaller frequency increments for a given frequency range to get a more comprehensive understanding of a system's dynamic characteristics. Pre-requisites: MSC Nastran Dynamics.

To learn more:

Progressive Failure Analysis (PFA) of Composite Laminates

   

The use of composite materials brings a number of advantages such as reduced weight, high strength or stiffness to density ratio, tailored stiffness and strength, and many others. The complexity of composite laminates are also accompanied with additional physical testing and higher costs than with traditional materials.

MSC Nastran PFA enables engineers to analyze the gradual failure of plies as a composite laminate is loaded, but without multiple structural analysis tools, excessive physical testing and associated costs. Pre-requisites: MSC Nastran Advanced Nonlinear.

Typical questions that may be answered with MSC Nastran PFA include:

  • What lies beyond first ply failure (FPF)?
  • Is FPF associated with abrupt failure?
  • How is the stress re-distributed over adjacent plies after a ply failure?
  • How far is FPF from last ply failure?
  • What are the design allowables?

To learn more:

MSC’s integrated solution for linear and nonlinear calculations facilitates reuse of models which saves a lot of time in pre- processing and enables us to standardize the data exchange formats for body models when collaborating with other departments or external suppliers”
- Sylvain Calmels Manager
PSA Peugeot Citroën
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