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Technical Paper

Fatigue Life Improvement through the “NOVA” Process

The experimental methods focused on utilizing the newly developed NOVA induction heating and hardening manufacturing process as an adapted method to produce high performance engine valve springs. A detailed testing plan was used to evaluate the expected and theorized possibility for fatigue life enhancement. An industry standard statistical analysis method and tools were employed to objectively substantiate the findings. Fatigue cycle testing using NOVA induction-hardened racing valve springs made of ultra-high tensile material were compared to data for springs with traditional heat treatment and those with standard processing. The results were displayed using Wöhler and modified Haigh fatigue life diagrams. The final analysis suggests that NOVA processed springs have a seemingly slight, yet significant benefit in fatigue life of 5 - 7% over springs processed through a competing method.
Technical Paper

Effect of Temperature on Weld Strength in Chrome Moly Space Frames

Chromium Molybdenum Steel (AISI 4130), commonly referred to as “Chrome Moly”, is one of the most popular materials used in the construction of tubular space frames and chassis components for racing applications. Its high strength, light weight and comparably low material cost make the reasons for its popularity quite obvious. However, there is one problem that is commonly overlooked: maintaining the strength component of Chrome Moly in areas exposed to high levels of heat followed by rapid cooling during welding. This paper seeks to better understand the affects of cooling due to welding on the strength of Chrome Moly tubing.
Technical Paper

Minimizing Cost of Material Variances in Printed Circuit Board Assembly

Controlling the Cost of Variance is essential to the manufacturing process of Printed Circuit Board Assembly for low volume high mix production. The material variance is identified as the additional components and resources consumed beyond the minimum required to complete the project. This Quantity Variance occurs at the effects of defects at key steps of the manufacturing process. Such occurrences result in the need to purchase additional components for the completion of the order. These additional components termed Quantity Variance alter the sequence of the manufacturing process affecting quality, timely delivery of the job and directly impacting company profitability.
Technical Paper

Shrinkage Analysis of a Constrained Thin Walled Injection Molded Component Using a Traditional Flatbed Scanner and Photometric Techniques

A study was performed to determine the effects of varying the wall thickness and material glass fiber concentration for parallel and perpendicular shrinkage rates for a constrained thin-walled box shaped component. An analysis of the shrinkage for the bottom portion of a 3 dimensional constrained thin walled injection molded component was performed using measurements made from bitmap images of the components that were obtained from a traditional flatbed scanner. The shrinkage rates were determined by comparing mold cavity hatch lines to the correlating transposed hatch lines on the plastic molded component. The perpendicular and parallel shrinkage rates were determined and are discussed as a function of thickness and glass fiber content. A wide range of processing control factors was used in the study.
Journal Article

Effect of Operational Testing and Trim Manufacturing Process Variation on Head Injury Criterion in FMVSS 201 Tests

This paper analyzes the difference in impact response of the forehead of the Hybrid III and THOR-NT dummies in free motion headform tests when a dummy strikes the interior trim of a vehicle. Hybrid III dummy head is currently used in FMVSS201 tests. THOR-NT dummy head has been in development to replace Hybrid III head. The impact response of the forehead of both the Hybrid III dummy and THOR dummy was designed to the same human surrogate data. Therefore, when the forehead of either dummy is impacted with the same initial conditions, the acceleration response and consequently the head Injury criterion (HIC) should be similar. A number of manufacturing variables can affect the impacted interior trim panels. This work evaluates the effect of process variation on the response in the form of Head Injury Criterion (HIC).
Technical Paper

Cold Temperature Effects on Spark Plug Performance

Fouling spark plugs on an internal combustion engine is greatly influenced by cold temperatures, especially at older assembly plants where the vehicle is moved several times because of discontinuities in the assembly line. To transition the vehicle, the operator starts the vehicle, places it in drive and accelerates rapidly, then shuts the vehicle off. This process only lasts ten to fifteen seconds and does not allow the spark plug or engine to get to a high enough operating temperature to evaporate away the fuel, which fouls the spark plugs. A spark plug fouling test is devised and is used to investigate which properties of fuel play the most significant anti-fouling role. Some additives believed to have anti-fouling properties will also be investigated to determine their significance. The anti-fouling fuel will then be implemented at the assembly plants.
Technical Paper

Redesign of a Differential Housing for a Formula Car (FSAE)

A unique differential assembly was needed for the Lawrence Technological University (LTU) SAE Formula race car. Specifically, a differential was required that had torque sensing capabilities, perfect reliability, high strength, light weight, the ability to withstand inertia and shock loading, a small package, no leaks, the ability to support numerous components. In that regard, an existing differential was selected that had the torque sensing capabilities, but had deficiencies that needed to be fixed. Those deficiencies included the following: Differential unit was over 4 kg unmounted, with no housing. This was considered too heavy, when housed properly. Bearing surface was provided on only one end of the carrier. This design provides insufficient bearing surface to support either the differential housing or half-shafts The internal drive splines integral to the case are not optimized for a perpendicular drive/axle arrangement, such as, a chain drive.
Technical Paper

Design of Formula SAE Suspension

Formula SAE is a Student project that involves a complete design and fabrication of an open wheel formula-style racecar. This paper will cover the suspension geometry and its components, which include the control arm, uprights, spindles, hubs, and pullrods. The 2002 Lawrence Technological Universities Formula SAE car will be used as an example throughout this paper.
Technical Paper

LED Junction Temperature Measurement and its Applications to Automotive Lamp Design

There are more and more LEDs being used in an automobile to replace the incandescent lamps. All those applications require high brightness LED work at high ambient temperature. However, the luminous flux output of a LED is directly related to its junction temperature. Higher the LED junction temperature, lower the luminous output from the LED. In order to efficiently apply LED to an automotive application the temperature effects on luminous flux must be accounted for in any design of a LED assembly. A LED junction temperature measurement system is described in this paper to measure the differential junction temperature between a reference LED and the LED under test. And the results are used to improve the LED assembly design.
Technical Paper

Design of an Aluminum Differential for a Racing Style Car

The 1999 Lawrence Technological University (LTU) drive train consists of a sprocket and chain assembly that delivers the torque, developed by a 600cc Honda F3 engine, to the rear wheels. The torque is transferred through a limited-slip, torque sensing differential unit comprised of a gear set in a student designed housing. The 1999 differential is a second-generation aluminum housing. The idea of using aluminum was first attempted with the 1998 team who successfully completed and used aluminum despite much complexity and a few design flaws. Therefore, in the LTU Formula Team's continuing effort to optimize the design, a new less complex design was conceived to house the gear set. This innovative design reduces the number of housing components from three in 1998, to two in 1999.
Technical Paper

An Adjustable Aluminum Differential

The 2000 Formula SAE Team at Lawrence Technological University (LTU) has designed a chain driven, three-piece aluminum differential unique from past years. This innovative design introduces an adjustable chain mount replacing conventional shackles. Made completely of aluminum, this device moves the entire rear drive train. The gear set remains to be limited slip with a student designed housing. The idea of an aluminum housing with manufactured gear set is a continued project at LTU. After cutting approximately 33% from the weight of the 1999 differential, the 2000 is geared toward a simpler, and smaller design, easier assembly and lighter weight. After reading this brief overview, the idea of this paper is to provide an understanding of the reasoning behind the choices made on the LTU driveline team. FIGURE 1
Technical Paper

Alternate Fuels: Not Only for Automobiles Propane Conversion of a Residential Lawnmower

The purpose of this paper is to present the design and assembly of a working prototype of an alternate fueled lawnmower. A variety of alternate fuels have been suggested to help reduce air quality problems. The conversion process from gasoline to Propane will be explained. To determine fuel consumption and developed horsepower, engine simulations were performed. Stoichiometric analysis was performed to determine and compare the products of combustion between Propane and gasoline. The prototype Propane fueled lawnmower is able to operate efficiently and with less emissions as compared with a comparable gasoline fueled lawnmower. Engine output has been reduced by 27%. By burning Propane, a relatively clean fuel, engine emissions have been reduced by 60% as compared to gasoline.
Technical Paper

Numerical Design of a Low Mass Differential Housing

Lawrence Technological University's 1998 SAE Formula car needed a high performance differential assembly. The performance requirements of a competitive SAE Formula car differential are as follows: Torque sensing capabilities Perfect reliability High strength Low mass Ability to withstand inertia and shock loading Small package Leak proof housing Ability to support numerous components With these requirements in mind an existing differential was selected with the capability for torque sensing. This differential lacked the desired low mass, support, internal drive splines, and proper gearing protection. The differential was re-engineered to remedy the deficiencies. The internal gearing from the selected differential was used in an improved casing. This casing and it's position in the car, reduce the number of side-specific parts required as well as improving the performance. The new design significantly reduces the size and mass of the assembly.
Technical Paper

Redesign of an Assembly Line Stop Mechanism for an Automated Palletized Transport System

A description is provided detailing the results of the quality function deployment process used to identify customer needs and requirements. Through this process two primary project goals were developed consisting of integrating an electrical-solenoid actuated device into existing space constraints and providing cost reduction alternatives. A static and dynamic analysis was initially required to find the boundary conditions of the external forces imposed on the existing pneumatic device while being subjected to multiple pallets impacting the stop block assembly. Further static analysis was conducted to find the internal forces imposed on the stop arm subassembly in order to properly size the electrical solenoid. Subsequent research into various solenoids led to two solenoid manufacturers evaluated by means of a design evaluation matrix.
Technical Paper

Experimental Investigation on the Influence of Pressure Wheel Design on Heat Dissipation for a Laser Robotic End of Arm Tooling

The initiative of this paper is focused on improving the heat dissipation from the pressure wheel of a laser welding assembly in order to achieve a longer period of use. The work examines the effects of different geometrical designs on the thermal performance of pressure wheel assembly during a period of cooling time. Three disc designs were manufactured for testing: Design 1 – a plain wheel, Design 2 – a pierced wheel, and Design 3 – a wheel with ventilating vanes. All of the wheels were made of carbon steel. The transient thermal reaction were compared. The experimental results indicate that the ventilated wheel cools down faster with the convection in the ventilated channels, while the solid plain wheel continues to possess higher temperatures. A comparison among the three different designs indicates that the Design 3 has the best cooling performance.
Technical Paper

Subtractive/Additive Rapid Prototyping of a Curve Spacer for Centrifugal Pump Impeller: Design, Manufacturing, and Simulation Analysis

This paper presents methods of rapid prototyping design and manufacturing used in the development of a centrifugal pump impeller with curved spacer (CS). In this research subtractive and additive rapid manufacturing methods were applied to create complex curved spacer profiles for testing as part of geometry optimization process for a high speed and high flow rate centrifugal pump impeller. Seven models for the curved spacer were designed and each model was integrated with the bare impeller separately for simulation analysis. One design was selected for manufacturing with applying subtractive and additive processes. In subtractive manufacturing method, the raw material was removed from a solid shaft by a cutting process under digital control from a computer file. The complexity of the modified impeller spacer profiles required the use of expensive CNC machining with five axis capability.
Technical Paper

Assessment of a Three-Semester Mechanical Engineering Capstone Design Sequence Based on the SAE Collegiate Design Series

Mechanical engineering students at Lawrence Technological University complete a five-credit hour capstone project: either an SAE collegiate design series (CDS) vehicle or an industry-sponsored project (ISP). Students who select the SAE CDS option enroll in a three-semester, three-course sequence. Each team of seniors designs, builds, and competes with their vehicle at one of the SAE CDS events. Three years after implementing major changes to the course structure and content, the three-semester capstone design sequence is revisited. Finalized learning objectives are presented and the sequence is assessed with a mix of direct, indirect, and anecdotal assessment. Student performance, as measured directly with design reports, milestones, and project completion, is good. Of the five Lawrence Tech CDS teams, only one has failed to be ready for competition since the changes were implemented.
Technical Paper

Optimizing the Rear Fascia Cutline Based On Investigating Deviation Sources of the Body Panel Fit and Finish

A vehicle’s exterior fit and finish, in general, is the first system to attract customers. Automotive exterior engineers were motivated in the past few years to increase their focus on how to optimize the vehicle’s exterior panels split lines quality and how to minimize variation in fit and finish addressing customer and market required quality standards. The design engineering’s focus is to control the deviation from nominal build objective and minimize it. The fitting process follows an optimization model with the exterior panel’s location and orientation factors as independent variables. This research focuses on addressing the source of variation “contributed factors” that will impact the quality of the fit and finish. These critical factors could be resulted from the design process, product process, or an assembly process. An empirical analysis will be used to minimize the fit and finish deviation.