Technical Innovations
Deere and MSC collaborate to reduce design time
 Deere used MSC.Adams for durability analysis on its rotary cutting systems. |
The implementation of durability analysis at the John Deere Welland Works, Welland, Ontario, contributed to reduced development time for its rotary cutter systems. On the last two product generations, each design and test cycle was completed in one or two weeks using a virtual prototype instead of several months required by physical prototypes. As a result, development on a 20-ft (6-m) cutter has been reduced to one year, compared to about two to four years in the past.
The 15- and 20-ft (4.5- and 6-m) Flex-Wing rotary cutters made by Deere are used by farm operators, road-side-maintenance companies, and municipalities for turf and grass mowing, pasture clipping, knocking down and shredding stalks, and clearing out brush. The heavy-duty, articulated cutter assembly consists of the center and two wings, as well as rotating cutting blade sets and support wheels. The sectional design floats to follow the ground contour, allowing uniform cutting height on hilly terrains while preserving the full cutting width of 15 or 20 ft (4.5 or 6 m).
Deere has traditionally relied upon a series of physical tests to ensure the durability of its rotary cutters when subjected to static and cyclic loadings. The most important test is performed on a bump-test fixture, which simulates the jarring and twisting impact a cutter experiences when running over large bumps and rocks. The cutter is attached to a grounded drawbar while the wheels ride on rotating drums—one for the center section and one for each of the wings. Triangular-shaped cleats attached to the drums are used to simulate bumps. "In the past, we had to keep building new prototypes and testing them on this fixture until we were satisfied with their life," said Terry Ewanochko, Product Engineer for Welland Works. "The prototypes are very expensive and take a long time to build and test. When we found problems with one or more major structural components, we would have to redesign and rebuild the prototype and start the testing again several times. This build-and-break process had to continue until the quality level was acceptable."
Determining that the design process could be improved while they were creating several small component-level virtual prototyping models, Deere hired Mechanical Dynamics (now MSC.Software Corp.) as consultants to use their ADAMS (MSC.Adams) multibody software to simulate the performance of several components. "We were impressed with the ability of the software to generate component-load profiles that can be used as input for fatigue analysis software," said Ewanochko.
Using the MSC.Adams/Durability product enabled complete integration of key virtual prototyping techniques such as FEA (finite-element analysis), multi-body simulation, and fatigue-life prediction. The initial MSC.Adams model of the cutter and test fixture was generated in PTC's Pro/ENGINEER environment using the embedded product MSC.Adams MECHANISM/Pro. This software package is seamlessly integrated within Pro/ENGINEER, so the consultants were able to perform kinematics analysis to validate the model without leaving the CAD environment, then perform one-button transfer to MSC.Adams where full dynamic simulations were performed.
 A tractor that provides a mechanical PTO together with hydraulic line tows the cutter. The PTO drives the rotating cutters while the hydraulic lines drive the actuator cylinders that are used to control the cutter height and wing lift. |
MSC.Software engineers finalized the model by adding higher-fidelity features such as contacts, bushings, motions, couplers, and more complex joints for the bump test. The flexibility characteristics of the structural parts were modeled by generating finite-element meshes of these components using Pro/MECHANICA and exporting them in the format used by ANSYS finite-element software. ANSYS was then used to generate flexible body modal neutral files that contain the modal mass, stiffness, and deflection characteristics using a modal representation of the component. The orthonormalized modes, including static correction modes, were computed within ANSYS and then transferred to MSC.Adams, which modeled the flexible body deformations as a linear combination of mode shapes.
The dynamic bump test was simulated in the virtual prototyping environment by first reaching static equilibrium for 1 s, then accelerating the drum operating speed. Using the full finite-element models of critical components, Deere engineers obtained local stresses with the MSC.Adams solution. The mode shape participation factors were used as the scalars on the stress solution of each mode shape in a linear superposition to represent the component's instantaneous stress shape. This superposition was performed at every node in the finite-element model for each time step in the simulation, making it possible to define a stress time-history at every location in the flexible component models. The modal coordinates, or scaling factor time-histories, were output from MSC.Adams for each component in a format that is directly readable by FE-Fatigue, a popular durability analysis software package from nCode International. Also, the stress solution for each mode shape was solved in ANSYS and exported to FE-Fatigue. FE-Fatigue then performed the stress superposition at every node for the purpose of life prediction. This involved automatic, multi-channel peak/valley extraction and rainflow cycle counting, followed by the damage sum.
Because the results of the durability analysis showed good correlation with Deere's physical test results on the initial prototype, the company integrated the virtual prototyping process midway into the development cycle on its 20-ft (6-m) rotary cutter, and from the very beginning of its latest 15-ft (4.5-m) rotary cutter.
- Jean L. Broge
Vansco's drive toward off-highway electronics
 While Vansco can provide custom solutions to OEMs, it offer off-the-shelf driver display modules that include stepper motor gauges, light indication panels, and a driver information LCD. Click to enlarge |
It is becoming increasingly important for off-highway OEMs to install body control systems and instrument panels as part of their overall electronic system approach. Body multiplexing eliminates point-to-point wiring, reduces or eliminates fuses and relays, and reduces installation and troubleshooting costs. The design approach of Vansco Electronics Ltd. allows for off-the shelf installation of a CAN bus-based control system while at the same time allowing an optional customer user interface. The system enables the vehicle drivetrain network and chassis control network to communicate and provide information from both networks to the operator. All modules are designed to meet or exceed SAE environmental specifications. The drivetrain network is linked to the chassis network and to gauges and displays through a gateway module.
Vansco's Pocket Gateway Module (PGM) is a general-purpose data protocol converter that can receive, translate, and transmit information over J1708, and J1939 protocols. The PGM has two J1939 ports, one J1708 port, and an RS232 interface. The PGM allows the manufacturer to connect the engine and transmission to the rest of the vehicle electronic system, isolating the different vehicle networks while allowing specified information required by the instrumentation to pass through bi-directionally. All other information is blocked, ensuring that the drivetrain network does not see unnecessary data that might hinder performance of the controllers on that network.
The Multiplexing Module (VMM) from Vansco allows manufacturers to reduce vehicle electrical system costs, while increasing flexibility in design and improving vehicle diagnostic capability. This system forms the communication backbone of the chassis. Each identical module communicates via the J1939 data network and passes sensor, switching, and lighting information to the driver interface. Since each module is identical in hardware and software configuration, the OEM only needs to carry one part number. The user-friendly software uses a ladder logic format in a Microsoft Windows environment to allow for easy programming and configuration changes, as well as simple diagnostics. The high-capacity, self-limiting outputs eliminate the need for breakers and fuses and can be used in parallel for higher current requirements. Two different modules are available, both capable of 12- or 24-V operation. The VMM 2820 has 28 inputs (digital and analog) and 20 outputs (18 high side only and 1 bi-directional). The VMM 1210 has 12 inputs (digital, analog, and frequency) and 10 outputs (8 high side only and one bi-directional). The modules have LED diagnostic indicators to allow users to quickly detect the location of a circuit fault.
Vansco's Driver Information Center is a two-line 20-character LCD display that provides vehicle data and programmable alarms. The user can adjust contrast and select imperial or metric units. The two function keys allow the user to choose the items to be displayed. The Lamp Indicator Module (LIM24) is a CAN module with 24 LEDs illuminating 24 icons on a graphic overlay. The overlay itself is a custom component for each machine while the module is a common part. The module can be installed without the use of fasteners using a friction-fitting gasket in a cut-out in the dash panel. PC diagnostic software allows a PC to be linked to the vehicle system through the PGM RS232 port. A complete view of the vehicle system including the engine and transmission can be seen from a laptop, allowing for easy diagnostics and vehicle repair.
As environmental regulations have forced manufacturers to install electronically controlled engines and transmissions, they are also looking for a cost-effective way to bring this data into the instrument cluster. The individual stepper motor instruments allow the OEM to have a complete instrument cluster system while keeping their tooling costs to a minimum. The gauges can obtain information directly from the vehicle data bus or from sensors through pressure and resistive sensing modules. Resistive sensing input modules and pressure sensing modules allow sensor data to be communicated to the gauges and the driver information center via the vehicle data bus.
The key benefits of the individual CAN bus stepper motor gauges include simplified vehicle integration, minimal behind-dash wiring, ease of installation, and serviceability. Compact stepper motor designs typically reduce clutter behind the dash thus improving serviceability. In contrast, air core gauge depth is approximately doubled. The precision Swiss-made stepper motors control needle positioning and provide accuracy to 1% on all gauges. Traditional air core gauges vary in accuracy from 5% to 10% from gauge to gauge. In the stepper motor system offered by Vansco, the speedometer acts as the master gauge by reading and translating the data bus information from up to 34 gauges. The microprocessor in each gauge then uses this data to control the position of the needle. As well, the speedometer interprets and distributes dash illumination dimming controls to all other gauges. The daisy-chain wiring harness links the gauges, thus simplifying the attachment of additional remote gauges, allowing off-highway OEMs to use the same system for various machines, as well as allowing for easy upgrades.
- Jean L. Broge
A commercial military
  As assistant product manager for the Army's new Stryker vehicle evaluates virtual designs with a contractor and a U.S. Army Training and Doctrine Command representative in the Tank-automotive and Armaments Command's National Automotive Center. The Advanced Collaborative Environments (ACE) lab in Warren, MI, allows the Army to combine tools such as the immersive 3D virtual world, like the CAVE Automated Virtual Environment pictured, with Internet applications. |
The resource pool ripples with possibilities as more than 450 companies join forces with the government in search of engineering innovations for commercial and military vehicles. A cluster of southeastern Michigan companies networked via the Automation Alley consortium and the National Automotive Center (NAC), a division of the U.S. Army Tank Automotive Research, Development and Engineering Center (TARDEC), recently signed an agreement that facilitates technology transfer benefits.
The Cooperative Research and Development Agreement (CRADA) between Automation Alley and the NAC allows all involved parties to stretch research monies and resources in pursuit of new technology. "It is technology-led economic development—that's really what this partnership is all about," said Mike Finney, Vice President for the Emerging Business Sector, Michigan Economic Development Corp.
TARDEC has various ongoing CRADA programs, each uniting the federal government laboratory with commercial companies or academic institutions. "The idea is to have more successes," said Dennis Wend, Executive Director of NAC at the U.S. Army Tank-automotive & Armaments Command in Warren, MI, adding that as many as 30 Automation Alley companies may soon be doing in-depth research studies with a number of the 1200 engineers and scientists working at the TARDEC.
Warren's NAC laboratories spotlight simulation and high-performance computing resources, providing capability for such work as structural analysis, propulsion system modeling, force-on-force modeling, track and suspension modeling and analysis, and interactive graphics/visualization such as the CAVE. "We're going from a four-wall (CAVE) environment to a five-wall configuration. You'll be able to view the virtual environment 360°, so you can turn in any direction," said Ken Ciarelli, Chief Engineer of the Advanced Collaborative Environments for TARDEC's NAC.
Another collaboration recently took flight. "We have a CRADA with Permo-Drive Technologies Ltd., based in Ballina, Australia, to take their (in development) Class 8-size hybrid hydraulic technology—otherwise known as a regenerative driveshaft—to a Class 6-size vehicle," said Donald Szkubiel, Medium Truck Platform Manager, Future Truck Systems in TARDEC's NAC.
The U.S. Army may install the system on various medium-duty tactical 5-ton (4.5-t) utility vehicles—such as cargo haulers, wreckers, and dump trucks—as a means of improving fuel economy, reducing emissions and saving on brake and driveline wear. Demonstration vehicles are expected in late 2002. "In 2005, we want to have a design-optimized, fully developed and tested system suitable for Class 6-size trucks, which are now powered by a heavy-duty diesel engine," said Szkubiel.
For the NAC/Automation Alley CRADA, all projects will use a dedicated high-performance computer system. "Depending on the needs, we may extend the platform," said John Schmuhl, Associate Director for High Performance Computing at TARDEC's NAC.
Per the CRADA, participating companies receive federal government protection from disclosures of any proprietary information, access to federal and non-federal scientists as well as up to five years' disclosure protection relative to research subjects and results after emerging from the CRADA.
- Kami Buchholz
