Some of the main advantages of event simulation is the need to make fewer assumptions. With event simulation, there is no need for elaborate hand calculations, interpretation of results, or experiments to determine equivalent loading. Fewer assumptions lead to fewer chances for errors.
Performing Event Simulation
You can perform event simulation with MES to model an entire design event, including imbedded motion and impact, and analyze it for linear or nonlinear dynamics.
Event simulation is performed in three stages:
- Setting up the model: Generate the model and set up the event simulation parameters.
- Analyzing the model: Execute the event simulation and monitor its progress.
- Results evaluation: Examine the results of the event simulation, including its animated history.
To perform event simulations, follow these general steps:
- Determine the type of element to use. Select from bricks, tetrahedral, beams, plates, 2D, and so on, to represent the geometry and type of analysis required. These elements may also contain mid-side nodes for models that are expected to experience bending. Joints or pivots can be included between two or more separate parts within the model. A joint or pivot is a shared node on two sub-parts of a model. A pair of scissors, for example, consists of two subparts and one pivot.
- Make a finite element model of the geometry of the part. An event simulation can contain more than one body and can also contact impact surfaces or other parts in the event.
Select the analysis from this list.
- Static Stress with Linear Material Models
- Static Stress with Nonlinear Material Models
- MES with Linear Materials Models - considers vibration, impact, and motion on the part or connected parts. Loadings resulting from changes in motion are computed and applied internally and automatically. Any local buckling is detected and shown on the screen.
- MES with Nonlinear Material Models - in addition to the MES with Linear Material Models analysis, this analysis can include nonlinear material behavior and nonlinear deformation.
- Specify linear material properties. Include the modulus of elasticity, Poisson's ratio and the shear modulus. For orthotropic materials, these values must be supplied for each direction.
- If materials are nonlinear, select a nonlinear material model and supply data as needed. If large strains or failure of the part under loading are a possibility, use an elastic-plastic material model. Using this type of model, you supply the yield strength of the material and a factor for the reduced strength after yielding in addition to the linear material properties. Consequently, if the part fails during the event, you witness the failure and the way it fails on the screen.
- Specify the length of time you wish to observe the event. You can extend this length later if the event takes longer, or cut it short. Additionally, specify the number of steps to take per second to calculate the displacements and stresses over time. The results of the analysis will only be output to the result files at these time steps.
- Constrain the model to simulate the actual conditions that it will experience. Specify boundary conditions which affix the model to set reference points with varying degrees of freedom.
- Specify load curves to use to scale the magnitudes of all the loads during the analysis.
- Specify the gravity or acceleration field, if necessary.
- Specify any revolutions or angular acceleration that the model can be experiencing. Rather than directly producing stresses, however, these items can initiate additional motion which in turn create additional forces (which create stresses) during an event.
- Specify any prescribed displacements. They produce an impact or acceleration, which can produce motion through space. Assign these prescribed displacements to a load curve. Prescribed displacements are specified as being applied by ramping up over time. These can be further modified, applied, or removed at any time during an event.
- Specify the location of all impact surfaces by coordinate position. Any contact between a part of the model and the impact surface is determined automatically. It is not necessary to specify which nodes make contact. All nodes are considered automatically.
- Specify forces and assign them to a load curve. This specification is optional and used only when such forces are known in a precise manner. Otherwise, structure the event so changes in motion determine the forces.
- Specify pressures and assign them to a load curve. Pressures are like forces except that pressure is defined as a force over an area. Using specified pressures is like using specified forces.
- . Specify initial directions of pressures. Pressures optionally change direction automatically as the model deforms or moves in space to retain their original orientation with respect to the surfaces upon which they were originally applied.
- Specify the mass density of materials so that mass can be calculated, its weight used for loading, and the inertia of the part can be utilized during the event. In addition, mass can be added or subtracted from the model at different points in time during the event. This feature is useful to simulate a subpart of the model being removed or added during the event simulation.
- Initiate an interactive process to perform the event. You can see the event proceed by live monitoring of motion, deformations, and stresses as they occur. Both graphical plots of values vs. time and graphical visual displays are available. Additionally, velocities and accelerations at points on the model can be monitored.
- Produce graphical plots of stress contours, motion, actual deformations for each step recorded during the event simulation. Obtain the minimum and maximum stresses during the event to facilitate fatigue analysis.
- Produce time-based animations of the event from start to finish in real time, fast time, or slow motion. Play these back with a multimedia program such as Media Player.
- Generate an HTML report of the analysis parameters and results.