Femap • NX Nastran

www.siemens.com/plmHigh tech and electronics

XyratexTest system manufacturer uses dynamics analysis as a competitive edge

the thermal environment), and contact by the robotic mechanism that inserts and removes the drives. Xyratex test equip-ment is specifi cally designed to isolate the hard disk drives from these and other sources of vibration.

Interactive mesh modifi cationsThe job of predicting vibration in new system designs falls to Thomas Hugin, a senior dynamics engineer, and his colleagues in the Technical Analysis group at Xyratex. “Too much vibration and the performance of the drives go down, so this is an important purchase consideration for our customers,” Hugin explains. “Our job is to guide the design to minimize vibration so that our systems meet the criteria supplied by drive manufacturers.”

Femap with NX Nastran simulations guide the design of testing equipment to minimize harmful vibration

Testing thousands of hard disk drives at a timeXyratex has more than 25 years of experience in research and development relating to hard disk drives, storage systems and manufacturing process technology. The company is divided into two business units: Networked Storage Solutions, which designs and manufac-tures a range of data storage solutions for original equipment manufacturers (OEMs); and Storage Infrastructure, which provides hard disk drive testing equipment that is used by hard drive manufacturers around the world.

Xyratex offers multiple confi gurations of its test equipment, but in general, these are large, automated systems that can evaluate the performance of thousands of hard disk drives at a time. With more than 7,000 test systems shipped, Xyratex estimates that its equipment is testing drives at a rate of 10 million parts per day, worldwide.

One of the key factors limiting the speed of testing hard disk drives is vibration. Too much vibration increases the time required for testing and thus limits the throughput of the factory. Sources of vibration during testing include the adjacent drives being tested, cooling fans and pumps (control of

IndustryHigh tech and electronics

Business challengesMinimize hard disk drives’ exposure to external vibrationPerform dynamics analyses fast enough to guide the design process

Keys to successComplete, interactive control over the analysis meshAbility to import and easily defeature CAD geometryMany options for presenting analysis results

ResultsDynamics analysis results guide design process1-day to 1-week turnaround on analysis requests NX Nastran solutions take about 15 minutes (550,000 node model with 3.3 million degrees of freedom)

Hugin uses Femap™ with NX™ Nastran® software from Siemens PLM Software to predict the dynamic performance of new test systems. He has access to other finite element analysis (FEA) solutions, including Ansys® software and Cosmos® software (the latter as part of the company’s computer-aided design (CAD) system, SolidWorks® software). He prefers the Siemens PLM Software solution because it gives him more control over the analysis process – from the creation of the finite element mesh to the presentation of the results.

“I have tried to do this work with other, more automated preprocessors, and I could not always get the mesh that I wanted,” Hugin explains. “Or, I could get it but only after finding work-arounds. With Femap, I can specify something like, ‘I want this many nodes in this direction,’ and the software does it.”

Hugin particularly likes the Femap Meshing Toolbox, which provides interactive mesh preparation functionality in a separate pane. “The meshing toolbox lets us go in after the mesh is created and modify it. It’s brilliant. We can even move a single node,” he says. “It’s interactive so we can instantly see how the mesh is being modified. I really like this feature.”

Working from CAD modelsAnother important aspect of the Femap meshing tool is that it simplifies the creation of analysis models from CAD geometry. In most cases, Hugin imports a CAD file into Femap to use as the basis for the finite element model. He doesn’t analyze an entire test system; that would be too large. Instead, he looks at a cell (the place where an individual drive is positioned during the testing process). In addition to its structure, a cell contains electronics and fans. The CAD model usually has some geometric features that aren’t important to the analysis, and Hugin removes these with the Femap

“I prefer Femap to the more closed, automated systems.”

Thomas Hugin Senior Dynamics Engineer Technical Analysis Xyratex

meshing tool. He has the option of feature suppression (removing features temporarily and only affecting the mesh, not the CAD model) or feature removal (actually deleting features from the geometry model permanently). Features can also be removed from an already-meshed model with an immediate mesh update, so it’s possible to interactively remove features and immediately view the effect on the mesh.

Because of the high frequencies that Hugin wants to simulate, the finite element models he creates are quite large. “The higher the frequency we want to analyze, the finer the mesh needs to be,” he explains. A typical model has 550,000 nodes with 6 degrees of freedom, or approximately 3.3 million degrees of freedom. The solution time using NX Nastran is about 15 minutes.

© 2011 Siemens Product Lifecycle Management Software Inc. All rights reserved. Siemens and the Siemens logo are registered trademarks of Siemens AG. D-Cubed, Femap, Geolus, GO PLM, I-deas, Insight, JT, NX, Parasolid, Solid Edge, Teamcenter, Tecnomatix and Velocity Series are trademarks or registered trademarks of Siemens Product Lifecycle Management Software Inc. or its subsidiaries in the United States and in other countries. Ansys is a trademark or registered trademark of Ansys, Inc. or its subsidiaries in the United States and other countries. MATLAB® is a trademark or registered trademark of The MathWorks, Inc. NASTRAN is a registered trademark of the National Aeronautics and Space Administration. SolidWorks and Cosmos are registered trademarks of Dassault Systèmes Solidworks Corporation. All other logos, trademarks, registered trademarks or service marks used herein are the property of their respective holders.Z13 25388 8/11 Cwww.siemens.com/plm

Siemens Industry Software

Americas +1 800 807 2200 Europe +44 (0) 1202 243455 Asia-Pacific +85222303308

Solutions/ServicesFemap with NX Nastran www.siemens.com/plm/femap

Client’s primary businessXyratex is a leading provider of enterprise-class data storage subsystems and hard disk drive capital equipment. www.xyratex.com

Client locationHavant United Kingdom

PartnerTEAM Engineering

Fast resultsThat solution time is fast enough to make dynamics analysis a key element of the design process. Hugin says that after he gets a request from a design team, he can usually have results back to them within a day to a week.

“Once we actually build the cells, we losethewindowformodification,soit’simportant to predict during the design phase the kind of performance we will get,” Hugin explains. “With Femap and NX Nastran, I can turn the analysis around fast enough to provide that kind of input to the designers.”

Hugin uses the Femap postprocessing functionality to generate images and reports. As with mesh creation, the advantage of using Femap here is control.

“Iliketheoutputfilesaswell.Wehavetremendous control,” Hugin says. He also exports analysis results to Matlab® for additional postprocessing.

In addition to the dynamics analyses performed by Hugin, engineers at Xyratex use Femap and NX Nastran to perform structural and nonlinear analyses as well. It is the dynamics analyses, however, that aresocriticaltothecompany’ssuccess.“Our customers look at dynamic performance, and the system with the lowest vibration is the one they want,” Hugin says. “Our use of Femap and NX Nastran directly addresses that concern.”