Search Results

Life-cycle analysis forces long-range planning, total cost visibility, enables a better understanding among different system components, helps identify alternate designs, and allows for effective, environmentally conscious manufacturing procedures. This paper will highlight the phases of a product life-cycle and the associated, product based cost models and environmental assessment for each phase. With this breakout of costs and assessment, indices and measures will be discussed which aid to optimally determine the most favorable options in designing for total product life-cycle.

As the primary material used in automobiles, steel's inherent recyclability has made it a leader in automotive recycling. And while recycling has environmental benefits, the use of steel in automobiles has environmental applications that originate with the steelmaking process and essentially have no terminus due to recycling. From the reuse of automotive parts to the continuing efforts toward actually using less steel for the same applications, today's and tomorrow's vehicles should be held up as examples of environmental compatibility.

This reearch presents a concept using effective road profile to calculate road loads. The method uses existing vehicle road load data, simplified vehicle dynamic model and simple tire model to create effective road profile. Then the simplified vehicle model is updated to reflect the vehicle changes of a new vehicle. Run the simplified new vehicle model to calculate road loads. The application of effective road profile in laboratory simulation is introduced. Preliminary CAE road load simulation using the effective road profile is presented.

CFD (Computational Fluid Dynamics) has been used to analyze vehicle air flow. In cross wind conditions an asymmetrical flow field around the vehicle is present. Under these circumstances, in addition to the forces present with symmetric air flow (drag and lift forces and pitching moment), side forces and moments (rolling and yawing) occur. Issues related to fuel economy, driveability, sealing effects (caused by suction exerted on the door), structural integrity (sun roof, spoiler), water management (rain deposit), and dirt deposit (shear stress) have been investigated. Due to the software developments and computer hardware improvements, results can be obtained within a reasonable time frame with excellent accuracy (both geometry and analytical solution). The flow velocity, streamlines, pressure field, and component forces can be extracted from the analysis results through visualization to identify potential improvement areas.

The plasticity characteristics of the material were used to model the cutting force material, and were verified by using FEM techniques. In addition, the solutions generated by The Merchant's Circle were proven by vector algebra, and a shear angle solution which uses the plasticity characteristics of the material is also presented. A good agreement was found between the mathematical models, FEM results, and experimental data results found in open literature.

During the last decade, several technological advances have taken place in the construction and fabrication industry in terms of methods, processes and tools which ultimately reduce fabrication time and costs. Fastening of metal plates with bolts and nutes in civil construction of large structures has recently been replaced by self drilling-tapping fasteners. The technique of using a self drilling-tapping fastener not only eliminates use of separate drills and drilling processes, but also eliminates the use of bolts and nuts. In addition, the time to join two plates by a self drilling-tapping fastener is significantly shorter than the time required for joining plates by conventional bolting methods. Although self drilling-tapping fasteners have many advantages, it is equally important that they demonstrate consistent performance in field applications.

Welding residual stress is one of the primary factors responsible for cracking at the access hole interface between the flange and web plate of welded heavy W-shapes. During multi-pass welding, cracks can be found in either the flange plate or the web plate, depending upon welding sequence, joint details and access hole size. In this study, an integrated numerical and experimental investigation was conducted to evaluate the effects of welding parameters and joint geometry on the magnitude and distribution of residual stresses in thick-section butt joints. The results provide guidelines for improved design for welding of heavy W-shapes.

This paper is an introduction to Formula SAE® (FSAE) suspension and frame design based on the experience of the design team at UM-Rolla. The basic theories and methodologies for designing these systems are presented so that new teams will have a baseline for their first FSAE design. Examples will be given based on UM-Rolla's 1996 FSAE entry.

This paper identifies potential performance benefits and computational costs of applying advanced multivariable control theory concepts to coordinate the control of a general multi-degree-of-freedom fuel system. The control variables are injection duration and pressure. The focus is on the design of a robust multi-input multi-output controller using H-infinity and mu synthesis methodology to coordinate the control of injection duration and pressure; reduce overshoots and system sensitivity to parameter variations caused by component aging. Model reduction techniques are used to reduce the order of the H-infinity controller to make it practically implementable. Computer simulation is used to test the robust performance of a generic engine and fuel system model controlled by the reduced order H-infinity controller and a traditional proportional plus integral controller.

The rapid prototyping process outlined in [1] has been updated to reflect the automotive industry's turn toward 32-bit embedded hardware and “C” software as well as enhancements in commercially available rapid prototyping systems. To exploit these advancements, Caterpillar, Inc. and Integrated Systems, Inc. (ISI), partnered to develop a PC-based rapid prototyping computer which provides the capability to rapidly test alternative control strategies using production-intent embedded system hardware (H/W) and software (S/W). The tool significantly improves the ease and reduces the experience level required by non-control system engineers employing the rapid prototyping process [1] and provides a stepping stone toward direct application of automatically generated C code to production embedded systems.

This research project investigates the feasibility of using a commercial finite element code to capture the dynamic response of a typical rubber-belted tractor for agricultural applications. The investigation focused on one of Caterpillar Inc.'s Ag Challenger Series tractors. A feasibility study concluded that Abaqus/Explicit [1], a finite element code utilizing the explicit scheme, had the desirable features needed to develop such a large-scale tractor model. These features include an efficient time integration scheme, three-dimensional generalized multiple contacts, and nonlinear material characterization. The fully-assembled tractor model was successful in simulating the forward motion. A preliminary validation indicated that the tractor model was able to predict a trend which was observed in field tests accurately.

Ground speed control of large wheel type loaders using the impeller clutch and brakes while the engine is at full throttle is investigated in this paper. The control strategy requires the engagement and disengagement of the impeller clutch or the brakes, making the closed loop system discontinuous. Use of a single control strategy such as a Proportional plus Integral (PI) or Sliding Mode (SM) controller may not result in a satisfactory response, particularly with respect to response time, vehicle jerk & acceleration, and chatter due to brake/impeller clutch switching. The sliding mode controller has a fast response time without causing instability, but may cause controller chatter in situations where the boundary layer thickness (an envelope around the sliding surface) is not sufficient. On the other hand, a PI controller can be made free of such controller chatter with appropriate gain selection. However, it tends to be slow responding when high overshoot is to be avoided.

Increased power and fuel efficiency requirements ofmodern vehicle diesel engines have lead to wide pread use of turbocharging to increase engine power-to-weight ratio. Typically, these systems employ pulse-turbocharging where an increase in exhaust gas transport efficiency is achieved at the expense of creating a highly unsteady flow through the turbine. This imposed unsteadiness is known to have a significant effect on turbine performance. To date, research performed to quantify the effects of exhaust pulsations on the performance of radial turbocharger turbines has been performed in off-engine facilities which simulate the engine manifold conditions. However, to better gauge the applicability of these data, a detailed investigation into the actual on-engine turbocharger operating environment is required. Research at Purdue University is focused on the characterization of the nature of the on-engine turbine operating environment and how it relates to turbocharger performance.

The range of applications of heavy duty diesel engines is quite diverse. The development of diesel engines has been characterized by a steady increase in power to weight ratios, with the turbocharger being the key component in achieving this increased performance. The turbocharger, consisting of a radial or axial flow turbine and a radial flow compressor, presents perhaps one of the most challenging tasks facing the turbomachinery designer. This is, to a p a t extent, due to the highly unsteady environment in which the turbocharger operates. The time scales of this unsteadiness range fiom those on the order of exhaust valve frequency to those associated with transient operation during acceleration and deceleration. In order to predict the time-accurate performance of the turbocharger in this environment, a range of dynamic models can be envisioned spanning the range from quasi-steady assumptions to full viscous flow solvers.

Many mobile industrial grinding machines utilize high inertia mechanisms to process the material they are grinding. The drive train of this type of equipment is typically expensive and requires some protection from torsional shock loads in order to eliminate costly equipment failures and down time. The torsional protection is typically provided by a device called a torque limiter. There are a variety of types of torque limiters available and the correct selection of the proper torque limiting device will be critical to achieve satisfactory life and performance of the drive train. There are many factors to consider in selecting the right device for the application, including but not limited to: horsepower to be transmitted, maximum torque to be transmitted, operating environment, frequency of torsional spikes, cost and size. Each type of torque limiter has its own advantages and disadvantages.

The differences between courses offered agricultural and mechanical engineers are examined. The topics in the courses are reviewed in some detail. The students start with a review of basic fluid mechanics followed by an introduction to bulk modulus. Governing equations for pumps motors and valves are introduced next. Course emphasis then diverges. The agricultural engineers cover the basics of control theory to cover a deficiency in their undergraduate curriculum. The mechanical engineers embark on more rigorous examination of the simulation of fluid power components. Students in both departments may elect to take a 1 cr. laboratory course. The laboratory exercises are discussed.

This paper focuses on the evaluation of seat comfort when a sitting person is subjected to vertical excitations. Three seat models have been proposed to highlight the selection of seat design parameters when subjected to impulses, multi-frequency sinusoidal types of vibration, and random excitation. These selected models are commonly used to describe human body vibration. Stiffness and damping coefficients were selected as the variable parameters in order to most effectively reduce the transmissibility of the vibrations from the floor to the human body. The results indicate that in the case of impulsive and sinusoidal excitations, the isolated seats, with suspension characteristics obtained through an optimization in the frequency domain, reduce the acceleration and absorbed power of the human body much more so than the passive suspension and hard seats.

The success of agricultural and construction machinery owes a great deal to the effective use of fluid power. Most fluid power systems are configured with a positive displacement fluid pump that is large enough to meet the flow requirements of many work circuits. Different work functions require a variety of fluid flow and pressure values to provide the desired operation. System branches, therefore, must include specialized flow and pressure regulating valves. The development of a mathematical model of a fluid flow control valve follows.

Multidimensional numerical simulations are performed to predict and optimize engine performance of a spark-ignited natural gas engine. The effects of swirl and combustion chamber geometry on in-cylinder turbulence intensity, burning rate and heat transfer are investigated using the KIVA multidimensional engine simulation computer code. The original combustion model in the KIVA code has been replaced by a model which was recently developed to predict natural gas turbulent combustion under engine-like conditions. Measurements from a constant volume combustion chamber and engine test data have been used to calibrate the combustion model. With the numerical results from KIVA code engine thermal efficiencies were predicted by the thermodynamics based WAVE code. The numerical results suggest alternative combustion chamber designs and an optimum swirl range for increasing engine thermal efficiency.

Presented in this paper is a nonlinear modeling and a controller design methodology for engine control. For illustrative purposes, the methodology is applied to the idle speed of a Ford 4.6L-2 valve V-8 fuel injected engine. The nonlinear model of the engine is based on a Hammerstein type model which is identified through input-output data without a priori knowledge of the engine dynamics. The nonlinear model is subsequently used in a frequency domain controller design methodology to achieve the performance goal of maintaining the engine idle speed within a prespecified asymmetric output tolerance despite external torque disturbances. An experimental verification of the proposed control law is included.