Noran Engineering, Inc. in the Media

U.S. Naval Academy Selects NEi Nastran Finite Element Analysis (FEA) Software

Westminster, CA.  September 17, 2007.  Noran Engineering, Inc. (NEi) a world leader in the development of engineering analysis and simulation software announced that the U.S. Naval Academy, Annapolis MD has selected its NEi Nastran Finite Element Analysis (FEA) software for use in its accredited degree program for the training of officers in Naval Architecture. The Academy’s curriculum covers many different types of ships, boats, and vehicles that operate on, above, or under water and involves the analysis and simulation of hull shapes, stability, structure, arrangement, survivability, maneuverability, and seaworthiness.  The objective is to have students learn modern techniques of marine vehicle design and analysis.

Noran Engineering's NEi Nastran has a solid presence in the U.S. Naval community offering highly specialized capabilities to Navy contractors such as the ability to simulate the response of ship components to shock loads like mine, torpedo, depth charge or missile detonation. Other important attributes of the software include full NAVSEA compliance, full integration of DDAM (the U. S. Navy's Dynamic Design Analysis Method, DDAM, used to validate ship borne shock sensitive equipment) into the core NEi Nastran solution for high productivity, and security features for the handling of classified data. In addition, Noran Engineering has demonstrated its responsiveness to maritime issues by winning a U.S. Navy funded Small Business Innovative Research (SBIR) project on applying FEA to the handling of components in ship construction.

Beyond the U.S. Navy, Noran Engineering's software extends to the global Marine engineering community covering the full breath of industry from defense projects and commercial vessels to luxury pleasure craft and high profile racing like the America's Cup and Volvo Ocean racing series.   A webpage devoted to the application of analysis and simulation software to maritime vessels and structures can be found at www.nenastran.com/marine . In addition, interested parties can sign up for White Papers, a Maritime Newsletter, and Webinars on analysis and simulation in marine engineering.

NEiFusion Receives Award from Design News Magazine

Design News magazine awarded Noran Engineering its 2007 Golden Mousetrap Award for Best Product in the Category of Analysis & Calculation Software for NEiFusion v1.2. The award was presented at the National Design Engineering Show in Rosemont, IL in October. The award was particularly satisfying for NEi because Design News magazine is read by 170,000 subscribers involved in mechanical and electromechanical design and product development. Plus, NEiFusion was selected above many established brand names because of the many new features that make it an effective tool at the CAD design stage for virtual test and design validation.

Some excerpts from Design News’ assessment and selection process follow:

“Looking for finite element analysis (FEA) capabilities, but aren't an FEA simulation specialist? Look no further than NEiFusion, Noran Engineering Inc.'s new approach to engineering analysis and simulation software. The FEA program is designed specifically for engineers doing design and product development”.

“NEiFusion takes a 3D, feature-based, paramatic CAD approach, making it feel more familiar and friendly to most within a product development team.”

“For engineers, more accessible and affordable FEA software opens the door to doing virtual testing earlier and more often in the design process. NEiFusion presents design engineers with an easy-to-use tool to assess the performance of their parts before prototypes are built, which aids in reducing design cycle times and boosting quality improvements.”

“The software's Pre-Processor module incorporates a comprehensive element library, meshing capabilities and an extensive materials library to insure real world fidelity. Its Post-Processor component provides a wide variety of images and graphs to view simulation results and is equipped with file sharing and import/export capabilities for easily sharing FEA models. NEiFusion also employs the same NEi Nastran Solvers found in Noran Engineering’s other analysis products.”

To read more about the award and go to Design News online coverage.

Noran Engineering Featured Success Story

Bender Shipbuilding and Repair Implements NEi Nastran with Immediate ROI

Noran Engineering was pleased to hear the positive impact that NEi Nastran had on operations at Bender Shipbuilding from Krishan Aluthpatabandige, Design Engineer. He outlined the major reasons for selecting NEi Nastran and the benefits they realized in the following commentary.  "Bender shipbuilding has been using Nastran products since March 2007.  Our Research and Development group started looking for an FEA tool to use in our Marine Engineering Department.  NEi Nastran was ultimately selected as one of the FEA software products to be frequently used at Bender.  Program capability, the level of knowledgeable support available from NEi engineering and cost were all key factors in its selection ."  

In our short relationship, NEi has supported us closely and their engineers have provided excellent support after the sale.  Another benefit includes a seamless interface with classification society.  NEi Nastran helped eliminate the need to submit several iterations of our design based structural simulations.  After using NEi Nastran, we have had no exceptions come back to us from the classification society, our projects are being finished quickly and our customer satisfaction is high.

We now have a team of NEi Nastran operators dedicated to design and verification. Our Marine Design Engineering Department frequently uses this tool to verify mechanical and structural designs and it has been used for new design, as well as repair projects.

The following screen shots are some examples of the work done with NEi Nastran."

Engine Foundation (first R& D project with NEi Nastran)          

Engine Foundation (first R & D project with NEi Nastran)          

Stern Roller

Stern Roller

Stern Roller (cut out)

Under Deck Structure (tank top)

Farr Yacht Design's Use of NEi Nastran Featured at EntertainmentEngineering.com

EntertainmentEngineering.com an online publication that covers the technical side of the entertainment industry, featured Farr Yacht Design's application of NEi Nastran analysis software to the design of ocean racing yachts. See the story below or visit www.entertainmentengineering.com.

Farr Yacht Design (FYD) uses NEi Nastran to enhance its structural analysis and simulation for its line of yachts. FYD is a leader in the design and engineering of high performance racing yachts for major events including the America’s Cup and the Volvo Ocean Race, as well as custom and production yachts for builders around the globe.

“Structural analysis is an increasingly important component of successful racing yacht design”, comments Dave Fornaro, FYD design engineer. “We have been utilizing FEA for several years to validate and improve our designs and desired to enhance our suite of analysis tools with more advanced capabilities in several areas including laminated composites, nonlinear surface contact with friction, and bolted joints with pre-load. After an exhaustive review, NEi Nastran stood out as the best choice based on its advanced capabilities, cost-effectiveness, and quality technical support.”

FYD’s first application of Nastran is for its next-generation of designs for the Volvo Ocean Race, a grueling round-the-world race sailed in fully crewed, 70-foot carbon fiber yachts capable of speeds in excess of 40 knots. “These designs are forging new frontiers in ocean racing,” adds Dave Fornaro. “They operate in harsh and brutal conditions and require a rigorous level of structural design and analysis to ensure peak performance and safety.”

Two Phases of Analysis

 A typical analysis for a racing yacht is split into two phases: global and detailed. In the global analysis phase, FYD models the entire hull, deck and internal structure as laminated composite shell elements. A typical model will contain approximately 125,000 elements. The composite materials are orthotropic in nature - that is they have different mechanical properties in different directions. This adds an extra layer of complexity as compared to isotropic materials such as metals.

According to Dave, “NEi Nastran has excellent capabilities for modeling laminated composite materials. We use spreadsheets to calculate the properties for individual plies and laminates (collections of plies) based on classical laminate theory. We have developed an automated method for transferring this data from the spreadsheets directly into NEi Nastran such that all ply and laminate definitions are read in with the correct naming and formatting of all mechanical properties. These properties are then applied to the appropriate areas of the model.”

Global models can contain as many as 150 different laminates, each with three plies representing two skins on either side of a core material. Several load cases are then run representing various typical sailing conditions as well as extreme load cases such as grounding or slamming in waves. These load cases are then post-processed in NEi Nastran and the results compared to criteria for global strains and deflections. This information can then be used to update the laminates as needed and re-run the analyses in an iterative fashion until all areas of the design meet the requirements.

“In the detailed analysis phase,” David said, “we look more closely at critical areas of the yacht that experience large strains.” Such areas are often at the junction of major structural elements such as canting keel pivot pins mounted into transverse bulkheads. For these detailed models, FYD’s design team will often remove a portion of the global model complete with enforced boundary conditions from a particular load case to use as the starting point. “We will then modify the models as required to study the areas of interest in more detail. Typically we will use a combination of solid and shell elements,” David said.

The solid elements are required in areas where transverse strains need to be calculated, or at contacting surfaces such as pin joints where through-thickness effects need to be captured. NEi Nastran has particularly good capabilities for modeling and analyzing contacting surfaces so as to accurately study pressure distributions and strains across the interface between the components. “This is very helpful for studying effects such as the distribution of loads among the fasteners in a bolted joint, including the effects of clamping and friction due to bolt pre-load,” David said.

Through the combination of global and detailed analyses, FYD is able to engineer their yachts to a much higher degree of fidelity than would be possible using traditional engineering methods alone. However, traditional engineering methods are still a very necessary part of the job, both for initial design work as well as for a check on the FEA results.         

Noran Engineering Product Release Information

NEi Nastran v9.2 scheduled for release May, 2008

You asked for it and now you are about to receive it.  The following lists include the top ten features that were recently released as well as the top ten features currently in Beta v9.2.  NEiNastran v9.2 is planned to be released in May 2008.

Recently released:

NEiNastran v9.2 scheduled for May, 2008 release:

Events and Trade Shows

SAVIAC Trade Show

Noran Engineering, Inc. participates in a wide range of trade shows. Most notably is SAVIAC which was held November 4 – 9, 2007. 

Tony Abbey conducted a tutorial which was very well attended, as usual.  Tony manages to make this tutorial informative and entertaining year after year.

Tony also presented two papers. One was the Creation of DDAM Benchmarks for Industry Acceptance and the Promotion of Good Practice. The second paper was A New Analysis Procedure for Automatic Impact Analysis in NEi Nastran.  NEi received immediate attention from NAVSEA with regard to DDAM benchmarks and is currently working toward consensus with NAVSEA for “tightening” specific areas of the 3010 that should result in less conservative results that will ultimately save on material costs. 

Tech Tips

Using the Stress Error Quantification in NEi Nastran

A recently added feature of NEi Nastran is a value which quantifies the stress error for shell and solid elements, addressing the issue associated with mesh density.

When using shell and solid elements for stress contours, it is difficult to know when you have enough elements to capture the stress adequately.  To provide a guideline for using both the Shell Element Stress Error and Solid Element Stress Error to determine when enough elements have been used, we created test cases where we incrementally increased the mesh size for various models to determine the Stress Error value corresponding to a 2% stress convergence.  The max von Mises stress was used to quantify the Shell Element stress error, whereas the max Normal Stress was used to quantify the Solid Element Stress Error.

For a von Mises stress convergence within 2%, a Stress Error of approximately 0.015 or less is needed for shell elements.  To achieve a Normal Stress convergence of 2%, a Stress Error of approximately 0.03 or less is needed from solid elements.

Shell Stress Error Contour for an L-shaped bracket with 32 Shell Elements.

Using the Extended Results Labels in NEi Nastran

There is now added support for extended results titles and labels in the FEMAP Binary results File (FNO).  The new labels are now up to 80 characters long and provide a better description of the associated results measure.

The parameter RSLTFILEDBLERPRCS under Output Control Directives allows you to turn ON/OFF the double precision option for the FEMAP FNO.  When set to OFF, it will use single precision data storage with extended length titles and labels.  When set to ON, it will use double precision data storage with standard length titles and labels.  The OFF option is only compatible with FEMAP versions 9.3 and higher an will provide better performance and more informative results labels.

In the two screenshots bellow you can see the difference in the results titles from when the RSLTFILEDBLERPRCS parameter is set to ON and when it is OFF.  For example the shell element bottom side principle stress reads “SHELL MINOR-PRINCIPAL-1” when set to ON and “SHELL MINOR-PRINCIPAL-BOTTOM” when set to OFF.

Standard Length Titles and Labels, RSLTFILEDBLERPRCS = ON

Extended Length Titles and Labels, RSLTFILEDBLERPRCS = OFF

If you do not know what some of the result vectors are, you can look up descriptions in Appendix A of the NEi Nastran Reference Manual.  Simply go to Start>All Programs>NEi Nastran> Documentation and open the NEi Nastran Reference Manual PDF file.  In Appendix A, results descriptions are separated into three types of results, Element, Grid Point, and Vector, and within each of these types they are separated by element type.