Introduction
The Structural Mechanics Module is tailor-made for modeling and simulating applications and designs in the fields of structural and solid mechanics. Engineers and scientists use it to design new structures and devices and to study the performance of existing structures.
With this module you can perform static and dynamic analyses in for solids (1D, 1D axisymmetry, 2D, 2D axisymmetry, 3D), shells (2D axisymmetry, 3D), plates (2D), membranes (2D axisymmetry, 3D), trusses (2D, 3D), wires (2D, 3D), beams (2D, 3D), and pipes (2D, 3D). Other examples of capabilities are thermal stress, geometric nonlinearities (large deformations), and structural contact.
Figure 1: von Mises stresses caused by thermal expansion in a turbine stator model. From the Structural Mechanics Module application library: Thermal Stress Analysis of a Turbine Stator Blade (turbine_stator). This model uses both the Structural Mechanics and Heat Transfer Modules.
The Structural Mechanics physics interfaces are the backbone of the module. These have predefined formulations for the capabilities described above. This guide gives an overview of these physics interfaces as well as examples of the modeling procedures used in them.
Geomechanics, Nonlinear Structural Materials, Composite Materials, Rotordynamics, and Fatigue
There are five additional modules available to enhance the Structural Mechanics Module: the Geomechanics Module, the Nonlinear Structural Materials Module, the Composite Materials Module, the Rotordynamics Module, and the Fatigue Module.
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With the addition of the Geomechanics Module, you can add soil plasticity, nonlinear elasticity, creep, concrete, rocks, brittle damage, and specialized soil models like ‘hardening soil’ and ‘modified Cam–Clay’ to the physics interface.
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With the Nonlinear Structural Materials Module, hyperelasticity, nonlinear elasticity, volume-preserving and pressure-dependent plasticity, porous plasticity, creep, viscoplasticity, brittle damage, and shape memory alloys can be modeled.
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With the Composite Material Module, you get the possibility to model layered shells, either using the Layered Shell interface, or through special material models in the Shell and Membrane interfaces.
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With the Rotordynamics module, you can study the dynamics of rotors, including advanced bearing models and gears. The rotor can be modeled either as beams, or using 3D solids. The hydrodynamic bearings can also be used in solid mechanics and multibody dynamics models.
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Using the Fatigue Module, you can augment your stress analysis with low or high cycle fatigue evaluation, including random vibration fatigue.
The Multibody Dynamics Module is a related product, which does not require the Structural Mechanics Module. Here, you can study rigid and flexible bodies connected by different types of mechanical joints, gears, cam–follower mechanisms, springs, and dampers. You can also model lumped mechanical systems, defined by components like mass, spring, damper, or impedance.
You will also find a subset of the structural mechanics capabilities in the MEMS Module and the Acoustics Module.
The exact contents of the menus and windows shown in this document may vary depending on the licenses you have. All illustrations assume the presence of these additional modules, even though the examples given only require the Structural Mechanics Module.
Structural Mechanics Simulations
Simulations in structural mechanics are used in a wide range of applications — from the microscale of MEMS components to the geomechanics scale of civil engineering. These types of simulations are also frequently used to study the behavior of existing structures, from microscopic biostructures to glaciers.
Structural mechanics was the first engineering field to use the concept of finite elements as a standard tool. Over time, these verifiable and validated formulations have been developed and are applicable to a wide range of materials. Simulations can often replace experimental measurements. For example, finite element simulations are used extensively in safety-critical applications within the aerospace and nuclear industries.
A traditional use of structural analysis tools is depicted below. The device being studied is a pipe with a bolted flange, and the purpose of the study is two-fold: (i) to estimate the stress in the pipe and (ii) to evaluate the performance of the bolted joint. Figure 2 shows the deformation and the von Mises stresses in the pipe.
Figure 2: The deformation (exaggerated) and the von Mises stress in the pipe. From the Structural Mechanics Module application library: Prestressed Bolts in a Tube Connection (tube_connection).
A less traditional application of mechanical design for a MEMS device is shown in Figure 3. The microactuator is subjected to controlled thermal expansion by the application of a current through parts of the structure, which induces Joule heating. The thermal expansion then causes the actuator to deflect and the simulation predicts the deflection as a function of the operating conditions. The simulation also reveals the limitations of the design, because the device will not work properly if the legs of the actuator make contact along the free faces.
Figure 3: The total displacement in a MEMS device. From the MEMS Module application library: Thermal Actuator (thermal_actuator_tem).
Structural analysis is also important outside of traditional structural engineering, for example in the field of biomechanics. Figure 4 shows the results of a simulation of part of the vascular system in a young child. The purpose of the simulation is to study what happens when surgery is performed on a child with a malformed aorta. The aorta and its ramified blood vessels are embedded in biological tissue. Pressure from the moving fluid is applied as a face load in the structural analysis. The Structural Mechanics Module includes several types of couplings for fluid–structure interaction.
Figure 4: Displacements in the blood vessel. From the Structural Mechanics Module application library: Fluid-Structure Interaction in a Network of Blood Vessels (blood_vessel).