Vehicle Dynamics Vehicle dynamics is the mechanics governing vehicle dynamic performance in the longitudinal directions (acceleration and braking), vertical and pitch modes (ride), and the lateral, yaw and roll modes (handling).

Ground Mobility Ground mobility is defined as the maximum speed-made-good by a ground vehicle between two points in a given terrain (on and off road). Speed-made-good between two points is the straight line distance divided by the travel time, irrespective of path. Hence speed-made-good is a measure of the intrinsic mobility of a vehicle in a given area, and this definition of mobility can be objectively established, and tested. Clearly, anything that will increase the average speed of the vehicle, and allow the use of a shorter, or more direct, travel path will improve the mobility of the vehicle.
With almost 25 years professional experience as Army's technical expert on ground mobility, and having developed Army's world class mobility and terrain analysis capability, I am well placed to provide specialist advice in this area.
Detailed analysis and advice can be provided on the following:

• Powertrain. Powertrain matching to ensure gradability, starting grade, acceleration, top speed, average speed, cruise speed, and fuel consumption.
• Handling. Analysis of suspension systems, roll centres, mass distribution, springs, dampers, auxiliary roll control, and tyre characteristics, to understand the behaviour of the vehicle during transient and steady state maneouvres.
• Ride dynamics. Vehicle suspension system components, sprung and unsprung masses can have a significant affect on the dynamic response of a vehicle. A less than optimum dynamic response can have an adverse affect on average speed, as well as driver and cargo shock and vibration inputs. My years of experience analysing ride dynamics, and the work involved in designing the unique Army Random Ride Facility have provided me with expert knowledge in this area. I can advise on how to optimise masses, springs and dampers to best satisfy ride and other performance requirements.
• Running gear. Tyre size and number of tyres can have a dramatic effect on vehicle performance, both on and off road. The solution for one soil type may not be the best for another soil, and the right off road arrangement may be detrimental to on road performance requirements. These effects can be quantified, allowing objective decisions to be made on the inevitable compromises that arise in this area.
• Terrain-vehicle interactions. Good vehicle systems integration requires the best balance of all the above subsystems, and this is best achieved by careful examination of the terrain-vehicle interactions, as they occur in concert, in the appropriate operational conditions.The problem cannot be adequately handled by looking at each subsystem and terrain-vehicle interaction in isolation. This is the very essence of the capability which I developed for Army, and hence have a sound understanding of how to advise on these issues.
• Vehicle trials. I have wide ranging experience in the design and conduct of vehicle trials. Coupled with detailed knowledge of vehicle systems and subsystems performance and simulation and modelling capabilities, I am well placed to advise on the design and conduct of trials to satisfy your requirements.

Other services

• Simulation & modelling. Simulation & modelling is thought of as today's technology. It has been around for a long time but is more well known today as we now have improved computers and software tools to help us make more use of the techniques.
  I have been simulating physical systems for more than 30 years, ranging from bespoke finite difference models to examine centrifugal and thermal stresses in an impeller which ran at more than 100000rpm; to blast overpressure models to examine how to protect an equipment operator from the blast effects of exploding HE ordnance; to complete vehicle systems models to examine overall ground mobility, and to quantitative digital terrain models which account for sub cell detail and temporal effects.
  I helped pioneer the use of Silicon Graphics systems in Defence to address the simulation and modelling needs, and have extensive experience with these systems and Unix.
  I can advise on the design of a simulation or model and the algorithms to solve your problem, and if required, develop the model for you.
• Digital terrain data. Having been responsible for the design of the methodology, and the development of the Army capability to generate quantitative digital terrain data to support ground mobility analysis, I am uniquely qualified to advise on what data you need to solve your problem, and the most effective way of populating your database.
  I have extensive experience with Geographic Information Systems.
• Data analysis. Data analysis is an often overlooked tool in the solution of a problem. How often have you (later) found that the cause of a problem was staring at you from your data?
  Data analysis has been a fundamental tool that I have used throughout my years of professional engineering. If you have a problem and a lot of related data, I may be able to assist.
• Technical writing. Technical writing was an important part of my engineering work for Army.
  My experience has included technical papers; user handbooks and similar documents; project and study reports; software documentation; submissions to senior management, and presentations to seminars, and international technical groups.
  My experience in this area has extended over more than 30 years. If you have a requirement for technical writing I can bring all that experience as well as mature engineering judgement to bear on your task.
• Problem solving All the above may have given you a bit of a picture of my engineering skills and experience. One of the important things I have learned over the years is that the best engineering skills in the world are not a lot of use if the problem hasn't been clearly identified!
  Don't fall for the trap of fixing the symptoms whilst ignoring the underlying problem!
  Whether it is a machine, some software, or an organisation that isn't working properly...or has a problem...I may be able to help you identify and solve that problem.
  
  
• Library. Technical reports and other useful material is available here for downloading.
  Please feel free to phone or email me to discuss any of the above

  

Professional Engineering - Advice - Analysis - Studies - Support

Terry Duell Consulting, 19 Rylandes Drive, Gladstone Park, Vic 3043, Australia, Ph +61 3 9338 4064

About me (caution...lots of images!)

23 May 2004

---

Email tduell@planet.net.au