MMAE Seminar - The Role of Computer Aided Engineering (CAE) in Automotive Engineering Applications
Armour College of Engineering's Mechanical, Materials & Aerospace Engineering Department will welcome Mr. Marcin Okarmus, Principal Engineer at Gamma Technologies LLC, on Wednesday, October 14th to present his lecture, The Role of Computer Aided Engineering (CAE) in Automotive Engineering Applications.
Abstract
Computer Aided Engineering (CAE) is one of the fastest growing fields within engineering and underpins design and analysis in all engineering disciplines. Virtual prototyping, based on the numerical analysis of structures, fluids, acoustics and many other disciplines, has become absolutely central to the industrial design and analysis process. CAE tools are very widely used in the automotive industry. In fact, their use has enabled the automakers to reduce product development cost and time while improving the safety, comfort, and durability of the vehicles they produce.
Mr. Marcin Okarmus, a graduate of Illinois Institute of Technology and the Principal Engineer at Gamma Technologies LLC, the company which develops and licenses GT-SUITE, the leading multi-physics CAE system simulation software, will present on the role of computer simulation in the design and analysis of structural components and complex mechanical systems. The importance of numerical modeling will be discussed in the context of the following automotive applications:
1) An Efficient, One-Dimensional, Finite Element Helical Spring Model for Use in Planar Multi-Body Dynamics Simulation
The helical spring is one of fundamental mechanical elements used in various industrial applications such as valves, suspension mechanisms, shock and vibration absorbers, hand levers, etc. In high speed applications, for instance in the internal combustion engine or in reciprocating compressor valves, helical springs are subjected to dynamic and impact loading, which can result in a phenomenon called "surge". Hence, proper design and selection of helical springs should consider modeling the dynamic and impact response.
In order to correctly characterize the physics of a helical spring and its response to dynamic excitations, a comprehensive model of spring elasticity for various spring coil and wire geometries, spring inertial effects as well as contacts between the windings leading to a non-linear spring force behavior is required. In practical applications, such models are utilized in parametric design and optimization studies. For that reason, computational efficiency is also a key requirement.
In this work, a helical spring dynamics model is presented, in which spring coils are modeled by means of one-dimensional curved beams. The displacements of these elastic components are expressed in a "floating" frame, which can undergo large rigid body motions in 2D space. The formulation thus enables modeling of planar displacements of the helical spring and captures the two-dimensional inertial effects associated with the rigid body motion/acceleration of coils but, at the same time, only requires a single degree-of-freedom per spring node. The Finite Element approach is used to efficiently discretize these elastic components and enables reduction of degrees of freedom required to accurately capture dynamic response of the spring. Furthermore, two different approaches for modeling spring coil-to-coil interactions are presented, i.e. "lumped" and "distributed".
The model has been implemented within a general-purpose multi-body dynamics analysis tool. In order to validate the model's accuracy, results from numerical simulation were compared to analytical solution of the hyperbolic partial differential equation governing helical spring dynamic response. Furthermore, experimental results from a static and dynamic spring compression tests of an automobile engine valve spring were used and compared to simulation results showing good correlation. Finally, computational efficiency of the presented model was studied in the context of a multi-body simulation of engine valvetrain system.
2) Methodology for Predictive Friction Modeling in Direct-Acting Mechanical Bucket Valvetrain System
Valvetrain friction can represent a substantial portion of overall engine friction, especially at low operating speed. This work presents the methodology for predictive modeling of frictional losses in the direct-acting mechanical bucket tappet–type valvetrain. The proposed modeling technique combines advanced mathematical models based on established theories of Hertzian contact, hydrodynamic and elastohydrodynamic lubrication (EHL), asperity contact of rough surfaces, flash temperature, and lubricant rheology with detailed measurements of lubricant properties and surface finish, driven by a detailed analysis of valvetrain system kinematics and dynamics. The contributions of individual friction components to the overall valvetrain frictional loss were identified and quantified. Calculated valvetrain friction was validated against motored valvetrain friction torque measurements on two engines. The system friction was analyzed across the operating speed range and at several oil supply temperatures as well as varying component surface finishes. A good agreement was observed between simulated and measured valvetrain friction torque suggesting that the proposed analytical methodology and the tool can be very useful in guiding new engine design and enhancing the performance of a given valvetrain design.
Biography
Mr. Okarmus graduated with the Bachelor's Degree in Mathematics from Dominican University, River Forest, IL and in Mechanical and Aerospace Engineering from Illinois Institute of Technology, Chicago, IL in 2002. He earned the Master's Degree in Mechanical and Aerospace Engineering from Illinois Institute of Technology in 2006. He also holds several Computer Programmer Certifications from College of DuPage, Glen Ellyn, IL. He is employed at Gamma Technologies, LLC located in Westmont, IL. His primary responsibilities are in the area of development and application of mechanical and hydro-mechanical simulation codes.