Newton, MA--Explosions. Collisions. Structural failures. Rare though these catastrophes may be, safety, liability issues, and other realities of modern life have forced engineers to design with them in mind. Fortunately, they have tools that help them predict the effect of these worst-case scenarios on their designs without destroying expensive physical prototypes.
Using finite element analysis and other simulation programs such as ABAQUS, ADAMS, ALGOR, ANSYS, COSMOS, I-DEAS, LS-DYNA 3-D, MARC, MSC/NASTRAN, MSC/DYTRAN, PAMCRASH, Pro/MECHANICA, and UAI/NASTRAN, engineers have computer-tested everything from faulty airbag activation to steering-mechanism failure. The payback: vital data that can help them optimize designs to lessen the dangers.
Accidents may sometimes be unavoidable, but engineering design can
lessen their impact.
Simulation and analysis software can point to potential problems or
explain how catastrophes happened.
The same analysis strategies that predict life-threatening failure
can predict small problems.
"Any mechanical system is a disaster waiting to happen, and that's what
analysis is for," says Algor President Michael Bussler. "It lets you simulate to
see if you're likely to have a catastrophe."
Few catastrophes would be more severe than a bomb explosion ripping through a crowded airplane at 32,000 feet. But, given the record of terrorist actions around the world, aerospace engineers can't dismiss the possibility. At Wright Patterson Air Force Base in Ohio, an engineering team has been running a series of analyses to predict the consequences of a bomb explosion in the cargo hold of commercial aircraft.
Using MSC/NASTRAN and MSC/DYTRAN, they are developing a "vulnerability map" that could form the basis for design and other strategies to improve planes' ability to withstand an explosion.
The aircraft they're studying: the 300 and 400 series of the Boeing 707. The team used MSC/NASTRAN's bar and plate elements to model longitudinal and transverse floor stiffeners, passenger window frames, door frames, membranes, and plates, among other features. They used MSC/DYTRAN to study the fluid-structure interactions during an initial blast inside the cargo compartment.
Analysis strategy. Among the initial results, the team has identified several steps engineers should take to determine the survival potential of an airplane after an inflight explosion:
Calcualte the allowable stresses for skins, frames, and longerons based on their material definition.
Identify the operating stresses on the forward fuselage for internal pressurization (8.6psi) and 2.5g load conditions.
Compute the design stress or the stress criteria for the structure as 30% higher than operating stress.
Perform a global MSC/DYTRAN analysis at a specific location and known charge size.
Superimpose the operating stresses on the stresses obtained at various times from the global MSC/NASTRAN analysis.
Remove from the MSC/ NASTRAN model elements that exceed the design stress limits.
In another example related to explosions, engineers at the Belvoir Research
Center in Fort Belvoir, VA, used ALGOR to design a mine rake for clearing a safe
path through mine fields, among the devastating weapons of choice employed by
Iraqi soldiers and the warring armies in Bosnia. The rake moves by lifting the
mines and pushing them aside to make way for heavy tanks and other armored
According to engineer Stephen H. Bennett, who performed the analyses on several variations in materials and geometry, one of the results was a large reduction in weight of the rake.
Liability the impetus. Beyond predicting the likelihood of disasters, analysis and
simulation software is sometimes a tool for determining how a catastrophe
happened. For example, engineers used Mechanical Dynamics' ADAMS to find out the
cause of a motorcycle crash. At stake in this case: the potential of a costly
Engineers modeled the cycle--two wheels, steering assembly, and frame--and the rider. For the latter, they used ADAMS Android, a tool for constructing an accurate model of a human body.
The results showed close correlation and helped establish operator negligence.
Many of the same analysis strategies engineers use to predict or explain these and other catastrophies are equally applicable to less life-threatening disasters such as structural failure of an exercise machine or computer enclosure. And that's the point, says Algor's Bussler:
"Simulation can help you predict and avoid catastrophes in design," he says, "and the tools are available to all engineers."
--Paul E. Teague, Editor
Design News showcases hot products, technology trends
Chicago--What's new in design? At this year's National Design Engineering Show, the Design News booth featured a diverse mix of new products and technologies, as reported in its most popular stories. The result was a look not only at what's new today, but the technologies of tomorrow.
New software programs, for example, now execute machine-code data on simulated NC machines, tools, parts, and fixtures. Visitors to the booth observed first hand "soft" machining operations, such as synchronous cutting on a dual turret lathe. "The ability to preview 'real machine' accelerations, feed rates, and tool change motions," says Lisa Lambro of SILMA, Div. of Adept Technology Inc., "eliminates the risk of damaging extremely expensive machine tools due to programming errors."
Also on display at the Design News booth: Smartplug™, a direct replacement for the ubiquitous spark plug. Patented by Automotive Resources of San Diego, CA, the device uses a catalyst-coated ceramic rod to improve an engine's combustion efficiency. "The conventional air/fuel limit is around 22:1," says President Mark Cherry, "but we've run at 28:1." Cherry also claims substantial NOx reductions--up to 90%--with no loss in performance. Auto-timed Catalytic Ignition, he predicts, may help engineers meet 1999 automobile emissions standards without exhaust after-treatment.
Automotive technology, and cars in particular, have always proven popular at the Design News booth, and this year was no exception. Chrysler's new Sebring convertible, cover story of the 1995 Design News auto issue, was designed from the very start to be a convertible. This should make it immune to conventional convertible shortcomings like body flex, noise, and leaks. Plus, it looks good.
Showgoers found Porsche's 911 Turbo on the stand as well. Dubbed the "Ultimate Porsche" in the Design News auto issue, this all-wheel-drive, 400-hp, 400-lb-ft sports car accelerates faster than most motorcycles from 0-60 mph, yet is claimed to be tame enough for everyday driving.
Chip vendors agree on performance rating spec
Sebastopol, CA--Advanced Micro Devices, Cyrix Corp., IBM Microelectronics, and SGS-Thomson Microelectronics have jointly developed a new microprocessor performance rating standard. The "P rating" expresses the performance of various microprocessors relative to comparably performing Intel Pentium chips.
The initial P-rating spec is based on the widely used Winstone® 96 bench-mark, employing 13 actual Microsoft Windows applications. Specification guidelines require a system-level comparison in which x86 microprocessors are tested in PC configurations with carefully documented peripherals. If, for example, a processor delivers performance equivalent to that of a 75-MHz Pentium, it gets a rating of "P75," regardless of its actual internal clock speed.
MDR Labs, launched by Microprocessor Report founder Michael Slater, supports the P rating and is performing the testing. Says Slater: "This is the first comprehensive and credible method for comparing competing processors. PC system manufacturers need a processor performance rating methodology that provides a consistent and objective way to rate Pentium-relative performance on Windows applications."
The first test results disclosed by the company are for
Cyrix's 6x86 chip. They show that the 100-MHz 6x86 delivers the performance of a
Pentium 120, the 120-MHz 6x86 provides Pentium-150 performance; and the 133- MHz
version equals the Pentium-166. The full report is available on MDR Labs' Web
site, http://www.chipanalyst.com .
Jade engineer wins Directory survey
Newton, MA--Richard Branco, mechanical engineer at the Jade Corp., Huntingdon Valley, PA, has won a $500 CompUSA gift certificate in the Design News OEM Directory survey.
Readers were asked for their opinion on whether the directory has been helpful, how often they use the directory and for what purposes, and if they might like next year's CD-ROM version. Branco's name was selected in a random drawing among those who responded to the survey.
OEM Directory listings are now on-line at http://www.dndir.com/ .
Technology turns out longer-lasting mufflers
Toledo, OH--A technology for filling car and truck mufflers will make its U.S. debut on 1996 Dodge Vipers and 1997 Ford F-150 pickups. Owens Corning patented the technology, based on the company's E-glass roving.
Walker Corp. has licensed the roving-filled muffler technology (RFMT) to produce its new Walker Quality Plus muffler. The E-glass roving system is said to last longer, be safer for the environment, and cost less to process.
Unlike basalt wool and other traditional muffler insulation materials, E-glass roving has high moisture resistance and less internal corrosion. The softening temperature of E-glass filaments ranges from 750 to 800C, which means lasting sound absorbency and fire durability. Also, the loosely structured fibers are uniform in diameter and allow for increased air flow.
The RFMT process places the roving inside the muffler shell, where it is blown up into wool-like insulation. The sound-deadening material will remain intact under the stresses of heat, vapors, and condensation. Because of its low density and resistance properties, E-glass evenly fills the muffler chamber.
The technology will adapt to meet manufacturing needs from a single manually operated machine or a fully automated muffler assembly line, including the new "clam-shell" mufflers. In contrast to traditional mufflers made of a closed cylinder with end caps, the clam-shell muffler consists of stampings joined together by a horizontal seam. This shape increases design freedom--mufflers can be made flatter and with more complex shapes to accommodate space under the vehicle. This, in turn, improves aerodynamics and leaves more space for a deeper trunk.
Owens Corning markets the glass fiber materials, as well as the RFMT equipment. Currently, Swedish automakers Volvo and Saab use the technology in Europe for cars and trucks.
New Ford truck features composite door
Inkster, MI--The latest addition to the Ford Aeromax Series truck line will, for the first time, highlight an all-SMC (sheet-molded composite) door with steel reinforcements in critical high-stress areas. The door will be used on 30,000 of the 1996-model trucks.
Eagle-Picher Automotive's Plastic Div. makes the doors. "This is a chance to show that composites can compete very successfully with steel," says Jim Grzelak, sales engineer for the E-P division.
The impetus for changing the door came from a Ford survey of truck drivers. One conclusion from that research, Grzelak reports, is that drivers wanted a door that was stylish, but still durable, without the corrosion issues associated with steel.
The SMC door was subjected to the same durability tests as a steel door, "and passed with very few problems," Grzelak adds. "In addition, the door is dent- and corrosion-resistant and has sound abatement. It also requires fewer parts than a steel door, which reduces assembly time and helps make the entire project very cost effective."
Eagle-Picher produces the two-piece inner and outer door using state-of-the-art processing, including robotic adhesive application and water-jet cutting. Although not done in this project, the door could incorporate the window mechanisms so they are mounted on an SMC insert fastened to the door.
Another benefit of using SMC: the door is 20% larger than its predecessor, but it weighs about the same. In all, the new Aeromax trucks incorporate about 450 lbs of SMC. Beside the door, the SMC parts include: front and fender extenders, hood, wind-deflector package (optional), and chassis side faring (optional).
"Historically, SMC was used for horizontal panels, such as hoods," Grzelak notes. "But, with fenders and now doors, a lot of design people are realizing that SMC can be used to make vertical panels."
Ford introduced its "Louisville" as a 113-inch bumper-to-back-of-cab length, medium conventional truck and tractor, with a body-side steel cab. It will complement the L-Series lineup, not replace any existing product at this time.
Thanks to "material-transparent" construction techniques, Ford can build the Louisville cab in corrosion-resistant, weight-saving aluminum, using the same gauge of metal, the same dies, and the same assembly tools used to construct the all-steel cab. The aluminum cab will be phased in as an option on highway-model Louisvilles. The lightweight, durable, corrosion-resistant composite doors will continue to be used on both steel and aluminum cabs.
Metal matrix composite gives zero-emission cars a boost
Phoenix, AZ--Conventional power modules haven't held up well in the constant thermal cycling of the electric-vehicle environment. In fact, their spotty reliability record has helped curb widespread use of these so-called zero-emission cars.
That problem could be resolved with the Hybrid Power Module (HPM) designed by Motorola Inc.'s Semiconductor Products Sector targeted for electric vehicles. The new motor-control power module features "space-age" materials, namely metal matrix composites (MMCs).
Motorola project leaders designed the MMC power module in solids, expecting the undertaking, like any significant departure from the conventional, to require lots of revisions. "We knew that introducing new materials would mean many process and design iterations," says James Fusaro, senior staff engineer and the team leader. "To accommodate the many changes we anticipated, but still provide a timely turnaround for each iteration, we chose to work from a core solid model on which all other operations were based."
The modeler used for the project: I-DEAS Master Modeler from SDRC, Milford, OH. Core solid models containing all facets of a design were used to construct geometry files and finite-element models. This information was transferred directly to external software, such as the ANSYS FEA system and the Ampere inductance program from Integrated Engineering Software Inc. Solid models also provided the main source of information for the stereolithography systems used for rapid prototyping.
Power modules for high-current applications typically house insulated gate bipolar transistors and free-wheeling diodes arranged in various configurations. In the past, the base plate for these modules consisted of copper. However, copper expanded more in response to heat than the other components within the module, causing high-stress areas that ultimately lowered the module's reliability.
To overcome this, Motorola turned to its patented MMC made of silicon carbide and aluminum. By offering a better thermal match with the other components, MMC eliminates areas of stress and improves reliability.
"In addition," adds Guillermo Romero, package design engineer, "it turns out that MMC has other advantages over copper. It weighs about two-thirds less, which means less energy is needed to power the car. And, normally with an ac drive system that uses copper, you need several modules per drive. Because MMC can be molded, you can conceivably combine several modules into one."
This project was a departure for Motorola in several respects. The company had plenty of experience with copper base plates, but a new material like MMC made it likely that the plate design would change. Also, they would need a new manufacturing process, since the MMC would be molded rather than machined. Experience told them that perfecting this product would take a lot of trial and error, and that led them to look at their development process. Here, SDRC's I-DEAS "won hands down," says Fusaro.
"This project represents a huge design paradigm shift in bringing in what we could call exotic or aerospace materials into the realm of consumer electronics," Fusaro concludes.
Mulally feted as Engineer of the Year
Chicago--Boeing's Alan Mulally picked up Engineer of the Year honors at the National Design Engineering Show last month, during a black-tie gala celebrating the profession's top achievers.
"I have lived an absolute dream," Mulally told about 250 banquet attendees. "I love airplanes...I wanted to make a meaningful contribution, and to be part of a big team." He was voted engineer of the year by Design News readers for his work heading the Boeing 777 project.
Senior vice president of airplane development and definition for Boeing, Mulally is "an ideal role model for any engineer who aspires to succeed in the 1990s," according to Design News Editorial Director Lawrence Maloney. As head of the "triple-seven" effort, Mulally oversaw development of a product that required 3 million parts from 18,000 suppliers, efforts of 350,000 people around the world, and an investment of $3 billion.
Mulally asked that the $20,000 Engineer of the Year education grant from the Torrington Co. be sent to his alma mater, the University of Kansas engineering school.
Eighty-seven-year-old John Hench was honored with the Special Achievement award for his half century of work at Walt Disney Imagineering, helping to bring Disney dreams to life. The Disney organization is "the very embodiment of team spirit," Maloney said. "They all work together to create Disney magic."
Hench requested that the $15,000 grant from NTN Bearing Corp. of America go to California State Polytechnic Institute's engineering school in Pomona.
Maytag's Vice President of R&D, Curran D. Cotton, garnered the quality award for leading engineering efforts to build dependability into the company's products. "At Maytag, quality was one of the first words that I heard when I joined the organization," he said.
Schneeberger Inc. donated $15,000 to Iowa State University's engineering school on Cotton's behalf.
Three Excellence in Design winners were honored as well, each receiving $5,000 awards from Computervision: Joshua Zulu, Caterpillar Inc., inventor of a continuously variable hydromechanical transmission; Dennis L. Vories, Consulting Engineer, who designed a hydrostatic altimeter; and Tommaso Rivellini, Jet Propulsion Laboratory, developer of a lightweight airbag-type impact attenuator to protect the Mars Pathfinder during its high-speed landing.
PC-based system improves ultrasound testing
Montreal, Canada--Ultrasound systems are expensive and can be difficult to use. Now, Perception Inc. has developed a PC-based ultrasound imaging system that may prove a cost-effective alternative to traditional hard-wired ultrasound systems.
To develop the HRS Scanner System, Perception needed to find off-the-shelf hardware and software that could handle stringent requirements. The company chose a Pentium-based computer to easily perform functions previously based on custom hardware. For the CPU to work efficiently, however, it needed real-time access to image data. The solution: a video card from Matrox Electronic System Ltd., Quebec, Canada.
During a scan, the sonographer moves a hand-held probe over the region of interest. The hardware generates a video signal, which is digitized by the frame grabber. The card then transfers the data to the system RAM in real-time. Perception selected the Matrox hardware because it offered both real-time transfer capabilities and an integrated display.
"We evaluated several video cards and software tools," says Albert Vara, chief software engineer at Perception. "We selected the Matrox card for its superior resolution and the ease of integrating the MIL software with our 'Virtual Console®' control system."
The control system replaces hardware-based knobs, levers, and switches with "virtual knobs" represented as software-generated icons on the computer's monitor. Features are activated and adjusted by either a touch screen or mouse.
"By using generally available hardware and software, Perception's system is not only less costly to build and maintain, but also more flexible," says Vara. "The 'Virtual Console' can be tailored to the user's requirements, and the system can be easily upgraded with off-the-shelf components."
Yacht design certified unsinkable
Malle, Belgium--Officials at Electro-Technical Apparatus (ETAP) say CAD technology has helped them design and modify yachts that exceed legal specifications for unsinkability. "The ETAP design ensures that, even when the boat is turned on its side and filled with water, it will right itself and can be sailed or maneuvered," according to Senior Design Engineer Frans Geukens--even if the boat has a hole in the hull.
The key is to inject a layer of close-celled polyurethane foam between the inner and outer hulls. Foam distribution and density are carefully calculated to ensure the proper distribution of buoyancy, he explains.
"The most interesting part of the design of an unsinkable yacht is also the most difficult piece of the boat to create: the so-called inner hull," according to Geukens. Engineers must weigh tradeoffs of living and storage space with the need to design in enough foam volume for unsinkability. ETAP uses EMS from Intergraph for the design work.
"With the computer, it is possible to calculate the volume and repartition of foam at the same time we develop the inner hull, so we can change the foam volume if necessary," he explains. "So, we are sure when we start making the expensive molds, the boat will meet regulations for unsinkability. We don't have to change the molds after testing the boat."
Repeated attempts by yachting experts in Japan, Europe, and North America have failed to sink any of ETAP's boat models. In fact, the firm's designs have been so successful staying afloat that they have been officially sanctioned by the French maritime authority to require no life raft for coastal cruising.
DEC claims workstation lead
Maynard, MA--Digital Equipment Corp. has significantly boosted the performance-per-dollar of its Alpha workstation line, slashing prices on the lower end of the family and speeding up the mid-range. Company officials say the products keep DEC ahead of the price/performance pack.
"We are maintaining substantial leadership in the workstation industry," says Ty Rabe, Digital's manager of CAD application marketing. DEC claims its AlphaStation 500/266 features 33% better performance when running Parametric Technology's Pro/ENGINEER than a Sun UltraSPARC 140, 61% better than an HP C100, and 78% better than an SGI Indigo2 R4440/250. And, Bob Irwin at Moog Inc., an aerospace manufacturer, said DEC's new workstations "outperformed the other vendors' offerings" running Unigraphics from EDS.
Digital says the AlphaStation 500, featuring 266-, 333-, and 400-MHz microprocessors, offers performance up to 11 SPECint95 and 14 SPECfp95 (new industry benchmarks for integer and floating-point performance). Prices range from $15,863 to $30,063.
The AlphaStation 255, with prices from $7,399 to $11,995, is rated up to 4.61 SPECint95 and 5.71 SPECfp95. These workstations use 21064A microprocessors with 233- and 300-MHz clock speeds.
DEC engineers redesigned some Alpha models into smaller desktop packages, versus earlier deskside enclosures, taking advantage of continued cuts in component size and cost.
The company also unveiled a PowerStorm line of PCI-based graphics adapters, supporting OpenGL graphics libraries, UNIX, and Windows NT. An 8-bit, 1280 x 1024 resolution card is priced at $399; the top-of-the-line $15,000 PowerStorm 4D60T will be available this summer.
'97 pickup offers muscle and comfort
If you're accustomed to thinking of trucks as work vehicles, Ford's new 1997 F-150 pickup will surprise you. I commute in my trusty '88 Taurus, and the test truck assigned to me handled quite as well as my car. Its nicely finished interior added to the car-like impression. The vehicle's ergonomics were excellent.
Ford uses a new 4.2l V-6 as the standard powerplant on the F-150. It develops 205 hp at 4,400 rpm and maxes out at 210 hp at 5,000 rpm. Torque reaches 255 lb-ft at 3,000 rpm. On road or highway, the engine kicks you along in quite an acceptable fashion. For those who want a bigger engine, Ford offers the 4.6l Triton V-8, which produces 210 hp at 4,400 and 290 lb-ft of torque at 3,250 rpm. The company intends to offer a 5.4l V-8 as an additional option this autumn.
Lest the unwary believe that the new F-150 lacks an appetite for hard work, Ford says the new pickups underwent more than five million miles of durability, developmental and fleet testing. Styleside and Flareside models will be offered in Regular Cab and SuperCab models, short and long-wheelbase versions, and 4 x 2 and 4 x 4 drivetrain configurations. Other options include captain's chairs, power seats, leather seats, a six-disc CD changer, and anti-theft systems.
Why all this foofraw for a class of vehicles once associated with contractors, farmers and the like? Well, according to Ford, about 90% of all new full-size pickups have been sold and registered, or leased, to individuals. And only about 1/3 of buyers surveyed during the 1994 model year reported using their trucks in their business. Instead, the number-one use for today's pickup is commuting. What differentiates the use of full-size pickups from cars, according to Ford, is the greater use of the vehicle for recreational activities. Also, pickup owners are no longer mostly rural folks. The pickup has gone suburban.
Handsome interiors, car-style options, and a standard third door on extended cab pickup models all demonstrate Ford's response to this trend. It's quite understandable, but to this editor seems a bit overdone. Where are the pickups of yesterday? I miss the bone-jarring ride, the lousy handing, the plastic seats of the pickups I drove in those years consumed by the locusts.
--Brian J. Hogan, Managing Editor