McLaren Performance Technologies: User Review - Expandable Solutions for Gearbox and Drivetrain Engineering
Overview
RomaxDesigner, by Romax Technology, provides a suite of tools for mechanical analysis of rotating components; gears, shafts, bearings, clutches and synchronizers, spline connections and housings. This software is of value to engineers responsible for gearboxes, transmissions, and vehicle drivelines. It is also of use to providers of components operating within those environments, especially bearings.
The unified approach is especially valuable when there are multiple non-linear interactions contributing to load, component stress, and misalignment. When components are operating near to their limits, the increased accuracy provided by the detailed analysis modules allow safety factors to be maintained while preventing components from being over designed.
Sometimes it answers the question "Why can’t you do that?" Sometimes the answer is "Actually, you can do that, if you do it right." In my organization more than one patentable (and counter-intuitive) concept has been brought through prototype development to production on the strength of a Romax analysis.
RomaxDesigner is modular software; with a base package allowing system level design and analysis, with modules available to provide detailed analysis of individual components. The base software can analyze systems on parallel axes, with extensions available to analyse perpendicular shafts and planetary systems.
Even in the base package, complex systems can be built and analysed, including non-linear and three dimensional effects. Each system component can be defined with a level of complexity appropriate to the desired analysis. For example, a bearing can be defined simply as a rotatable support with specified flexibility, a catalogue-level design with ISO capacities and macro geometry, or with full micro-geometry, life adjustment factors, and high speed inertial effects.
System Definition
A system is divided into subsystems, such as gear trains, housings, and shaft assemblies with their bearing supports and gear connections. Base modules define components using an industry-standard closed-form equation.
With more advanced modules, individual components can be converted to more finite element-like models. For example, a housing can be defined according to its stiffness, (using a reduced stiffness matrix from a finite element model) or as a finite element model solved within Romax (an advanced module).
As the model is developed, further detail can be added to each component as needed. The entire system can be subjected to a duty cycle, with multiple conditions of speed, load, and temperature defined, allowing simultaneous cumulative damage analysis of all components. Multiple duty cycles can be defined, reflecting different applications.
Shaft Models
Shafts are modelled for deflection and stress using closed form equations for beam segments. It is also possible to use FE models for more complex shaft geometry. The user can choose from pre-defined materials and stress concentration factors, or develop their own. The base package can model parallel and concentric shafts. Perpendicular shafts and moving axis (planetary) shafts can be modeled with extended modules. An additional module is available to analyse fatigue.
The software can define and analyse shafts that are connected at non-90 degree angles, though the gear definitions for these systems are limited.
Bearing Models
The Romax base package provides standard bearing life and load capacity analysis using ISO 281:1990 or ISO 291:2007. The program also includes a modified rating with a closed-form calculation of effects of misalignment. The built-in database includes data from four bearing manufacturers' catalogues. Additional bearings can be defined and saved by the user.
The bearing search tool allows quick access to all four catalogues plus the user-defined bearings. Bearing models provide nonlinear stiffness interactions with adjacent components, which can be critical when calculating gear support stiffness, gear mesh misalignments and preload requirements.
When calculating bearing life, the models include the effects of misalignments developed through the flexibility of any coupled components. A bearing preload tool automates studies of bearing life as a function of preload. RomaxDesigner does not currently include the effects of localized housing distortion on bearing roundness, and it does not include a direct way to include the effects of thermal expansion on bearing fit and preload. Advanced bearing analysis modules provide detailed analyses (ISO 281 Supplement 4), including contact stress, fluid film thickness, and stress-based life calculation. Advanced bearings can be defined with an assortment of pre-defined roller and raceway crowns, or with a measured crown.
Gear Models
Romax models may include spur and helical gears, and with the perpendicular axis module, bevel and hypoid gears. The base software models gears with enough detail to analyze their effects on the rest of the system.
Additional modules allow design and rating to AGMA, DIN and ISO standards. For parallel axis gears, additional modules permit macro-geometry definition and optimization for manufacturability and detailed analysis of micro-geometry for contact stress and transmission error. For parallel and perpendicular axis gears, Romax can interface with more detailed analysis software, and act as a "front end" for even more computationally intensive formulations of bending and contact stress.
The combination of these two software packages is particularly powerful, as it permits cumulative damage life analysis including the non-linear effects of gear tooth deflection and bearing stiffness, acting on a fully developed tooth profile.
Graphical Results
RomaxDesigner graphics are suitable for a variety of reporting illustrations, such as system topology and component deflection.
Additional Capabilities
In addition to the AnSol software, RomaxDesigner modules are available to interact directly with other simulation software packages, such as SIMPACK, and LDP, as well as several FEA and CAD packages. Additional modules are available with primary focus on NVH and dynamic characteristics, such as gear rattle and whine, system modal analysis, and clutch analysis. Modules are also available to automate optimization and sensitivity analysis of system and component designs.
Ease of Use
Romax no longer includes self-directed tutorials with the software. Training is available directly through the company. Course content and duration are customized to the needs of each organization; a one week training session would be sufficient to cover the basic modules and a few advanced topics.
Many highly specialized software packages require constant use to become and stay proficient; I find that RomaxDesigner does not require this level of attention. An engineer with other responsibilities will find this software functional even if not used on a regular basis.
System Requirements
RomaxDesigner runs under Windows (XP or 2000 are recommended, Vista is supported). It operates in the 32 bit or 64 bit environments, though most components are 32 bit applications. Hardware requirements are modest; as with any powerful software an additional investment in RAM and processor speed are worthwhile.
Most Parts of RomaxDesigner do not currently take advantage of multiple processors, though a dual or quad-core system can speed results by permitting RomaxDesigner to operate undisturbed in a single core.
About the Author
McLaren Performance Technologies is a member of the Linamar Group of Companies. Linamar manufactures mechanical components for automotive, aerospace, power generation, and consumer products industries. They have been using RomaxDesigner for about 8 years, primarily analysing components in four wheel drive and all wheel drive vehicle drivelines.