Simulating Coupled Longitudinal, Pitch and （模拟耦合纵向,音高和）.pdfVIP

Modern Mechanical Engineering, 2012, 2, 176-189 /10.4236/mme.2012.24023 Published Online November 2012 (http://www.SciRP.org/journal/mme) Simulating Coupled Longitudinal, Pitch and Bounce Dynamics of Trucks with Flexible Frames D. Geoff Rideout Faculty of Engineering and Applied Science, Memorial University, St. John’s, Canada Email: g.rideout@mun.ca Received August 7, 2012; revised September 8, 2012; accepted September 19, 2012 ABSTRACT Simulating the dynamic response of trucks requires that a model be constructed and subjected to road inputs. Inclusion or omission of flexible frame effects is often based on intuition or assumption. If frame vibration is assumed to be sig- nificant, it is typically incorporated in one of two ways. Either a complex finite element model of the frame is used, or a simplified linear modal expansion model (which assumes small motions) is employed. The typical low-order modal expansion model, while computationally efficient and easier to use, is limited by the fact that 1) large rigid body mo- tions and road grade changes are not supported, and 2) longitudinal dynamics are not coupled to vertical and bounce dynamics. In this paper, a bond graph model is presented which includes coupled pitch and bounce motions, longitudi- nal dynamics, and transverse frame vibration. Large rigid body motions are allowed, onto which small flexible vibra- tions are superimposed. Frame flexibility is incorporated using modal expansion of a free-free beam. The model allows for a complete pitch-plane representation in which motive forces can propel the truck forward over varying terrain, in- cluding hills. The effect of frame flexibility on vehicle dynamics can then be studied. This is an extension of the typical half