New Mechanical Event Simulation Features Expanded 

By Daniel W. Pangburn, P.E.

The most notable developments ALGOR has recently introduced focus on its FEA-based Mechanical Event Simulation (MES) capabilities. In addition to MES enhancements, the latest version of the software also features CAD support, a wide range of mesh generation options, a user interface with right-click functionality and FEA improvements, including multiphysics enhancements. The common goal of all of these enhancements is to enable engineers to reduce physical prototype testing, thus reducing costs and time-to-market.

Tools for Simulating a Wider Range of Motion Scenarios 

MES calculates motion and stresses with built-in linear and nonlinear material models. The set-up of an MES uses only physical data, rather than calculated or assumed loads and boundary conditions. Because assumptions are not required, this type of simulation saves time in the CAE process and reduces the number of prototype tests. It also provides a more accurate and comprehensive analysis with more information about the dynamic loads and the way the design reacts including full, dynamic visualization of the behavior of the part for easier evaluation of results. 

Many enhancements enable engineers to simulate a wider range of motion scenarios. For example, the new actuator element enables engineers to simulate axial extension and retraction in three-dimensional space as well as rotational motion. It can replicate complex, computer-controlled motion over time in any direction and it can simulate the relative axial rotation between the ends of the element. I have previously simulated actuators with solid “pusher” elements and prescribed displacements, but the actuator element offers far greater control and avoids unwanted direction changes as the result of deformation. In addition, the induced forces of an actuator can be graphed with the post-processing tool, Monitor, providing graphical results output with hard copy if desired. 

Another new MES element is the slider element, which is composed of three nodes where the center node follows the path created by the line between the other two nodes. This element enables engineers to simulate slots or guides within mechanisms. 

Other utilities include the new KinePak and Timeline tools and an improved mass properties calculator which now also calculates products of inertia. The KinePak mechanism wizard enables engineers to define links and then dynamically examine the motion of various types of basic mechanisms including, four-bar, toggle, slider/crank and levers. Timeline is a utility for editing and viewing the multiplier data associated with a time-dependent loading event. With the editor, users enter curves into a spreadsheet-style dialog or defined with built-in functions to define individual events or loads. The viewer helps engineers validate event setup by displaying curves and seeing how loads will act on a model during analysis — their activation and deactivation times and how their magnitude changes over time. Products of inertia calculation have been added to the mass properties calculator to determine the dynamic balance in spinning structures. The mass properties calculator also outputs weight, volume and center of gravity for all models. 

Full Extensibility within CAD

Until recently, I used universal geometry file imports to interface with CAD. Today, I use ALGOR’s InCAD technology in my consulting work because it offers several advantages. First, InCAD technology captures the exact assembly or part geometry in coordination with the CAD API, eliminating file translation problems that can arise with universal geometry file formats. In addition, it works with a variety of CAD solid modelers including Autodesk Inventor, CADKEY, Mechanical Desktop, Pro/ENGINEER, Solid Edge and SolidWorks. Lastly, InCAD has the same interface and operations regardless of the location of CAD and FEA systems; the CAD system used; and the analysis types needed, including linear and nonlinear stress, linear dynamic stress, fluid flow, heat transfer, electrostatic and even more advanced analysis such as FEA-based motion and stress analysis. Making a full range of FEA capabilities available within a number of CAD packages gives engineers maximum flexibility in choosing compatible CAD packages and filling a wide range of analysis needs. 

New Interface with Right-Click Functionality

As a long-time user of ALGOR, one big change I have noticed is the graphical user interface. The new FEA editor environment offers right-click functionality across the entire software line. This interface enables right-click application, modification and removal of loads, constraints and finite element properties for all analysis types, including Mechanical Event Simulation. In addition to providing convenient means for selecting nodes, parts and surfaces, the interface offers more feedback about selections visually in the form of highlighting and textually with the specific vertices selected listed in the tree view. The tree view of model parts and associated data also graphically indicates which parts have associated data and where data is needed, adding valuable perspective in the design process.

Shown within ALGOR’s graphical user interface with right-click functionality is a model of a semi-trailer underride bumper. The interface includes a tree view of model parts and associated data (left) and Windows-native functionality like multiple model views (right). Model courtesy of Daniel W. Pangburn, P.E.

The FEA editor is Windows-native and so all input screens for all loads and constraints offer standard functions such as copy and paste support. The docking toolbars can be arranged to a user’s preference and multiple views of the same model can be open at the same time. The interface also provides dynamic viewing of FEA models, including automatic zooming using the scroll wheel on the mouse. The models are automatically shaded for realistic visual feedback. 

Multiphysics and a Full Range of FEA 

More realistic simulation is also supported by a range of analysis capabilities, which includes static stress analysis with linear and nonlinear material models, steady and unsteady fluid flow analysis with turbulence, steady-state and transient heat transfer analysis, electrostatic analysis, linear dynamic analysis and multiphysics.

An important consideration for engineers is always processing speed. New fast solvers use sparse solver technology to provide significantly faster processing times, especially when analyzing large CAD models. Faster solvers are critical to reducing analysis run times and shortening the entire design process. This is especially important when considering stresses in a large CAD assembly for transient analysis.

Multiphysics capabilities have also been augmented. New capabilities include a forced convection heat transfer capability for considering the effects of fluid flow when solving for temperature distribution and a film convection coefficient calculator to estimate the heat transfer coefficient between a solid and adjoining fluid. These new capabilities make thermal/fluid scenarios easier to perform than ever before. 

In addition to adding new multiphysics capabilities, many existing capabilities are more tightly integrated, such as thermal/structural and electrostatic/structural multiphysics capabilities. Now, the results of one analysis can be automatically applied as the input to a second analysis with just a few mouse clicks. 

No matter what type of analysis you choose to perform, built-in report features are valuable for documenting the results. The Report Wizard automatically generates a clearly organized, web-ready report with details about a model and its analysis results. In addition to data from the model files, reports can include user-defined images, animations, models in VRML format and graphical plots, including plots of actuator force vs. position graphs for a large deformation plastic analysis.

The semi-trailer underride bumper model was analyzed with ALGOR’s Mechanical Event Simulation (MES) software for predicting motion and stresses with built-in linear and nonlinear material models. In addition to reviewing stresses (upper left), Pangburn created a graph of force and energy over displacement (lower right). An actuator element was used to initiate the displacement of this large deformation plastic simulation. This project required many computerized design iterations to get a cost-effective underride bumper that would pass the government specifications for withstanding forces and absorbing energy during collapse.

Conclusion 

In surveying the latest release of ALGOR software, what impressed me most is that while many capabilities have been added for simulating a wider range of motion scenarios, ease-of-use functionality has been added to make FEA accessible to more engineers. Not to be overlooked is the very high productivity possible as a result of powerful modeling commands, seamless cooperation with CAD programs and fast desktop results.

Daniel W. Pangburn, P.E., holds B.S. and M.S. degrees in mechanical engineering and has over 47 years of experience in engineering and engineering management positions. Besides consulting, he has worked for Aerojet and Northrop Grumman Electronic Systems and holds several patents. He resides in Fullerton, California.