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.
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:
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:
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.
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:
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.
The dynamic aeroelasticity capability provides analysis in the time or frequency domain. The following capabilities are available:
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.
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:
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:
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.
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*Access to ZONA51 is available through MSC Nastran Aeroelasticity II
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.
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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
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.
Implement Shape Optimization to optimize the profile of your designs. Specific boundaries may be selected and allowed to vary during the optimization process.
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.
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.
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.
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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.
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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.
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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:
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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