Search Results

The rate of energy absorption during the plastic deformation of structural components is an important factor in the design of automotive safety systems such as chassis crumple zones. This paper describes a design tool for predicting energy absorption characteristics. The tool was based on measurements of the energy absorption rates of twenty-three selected materials subjected to three impact energy conditions. A well-established finite element code, LS-DYNA3D, was used with a mesh representing a hollow column of square cross-section to establish a database of energy absorption characteristics. A mathematical model representing the energy absorption rates was determined and the material properties most influencing the energy absorption rates were identified. A parabolic model best represented the energy absorption charactersitics. The regression coefficients for the model were determined for all tested materials under the selected test conditions.

A neat, alkali-refined sunflower oil, a 50/50 blend (v/v) of sunflower oil and #2 diesel fuel, and 100% #2 diesel fuel were evaluated in a direct injected, one-cylinder Petter engine according to the SAE 13 mode test procedure. The experiment was conducted to evaluate the effects of plant oil based alternative fuels on exhaust emissions and to simultaneously compare the test fuels. Additionally, the effect of engine load and speed on the exhaust emissions using the plant oil alternative fuels was statistically evaluated. The response variables were CO, NO, HC, and smoke. The predictor variables were the concentration of sunflower oil in the test fuel, the engine speed, and load. A multivariate test and covariance analysis were used for the results evaluation.

The paper* describes the analysis of experimental results of a laboratory flow apparatus used to measure the energy released during premixed combustion at atmospheric pressure in near quiescent air. The flow apparatus, described in a parallel paper, has the means to provide air temperatures in the range between 800 and 950° K. An infrared radiation detector and a photodiode sensitive to radiation in the visible range of the electromagnetic spectrum monitor the events taking place inside the combustion chamber through a sapphire lens. A beam splitter permits simultaneous observation of the combustion events by both sensors. The difference in response times between the two sensors offers information about the non-luminous premixed combustion. Four fuels, No. 2-D diesel fuel, a 50/50% volumetric mixture of diesel fuel and sunflower oil, neat sunflower oil, and neat high oleic safflower oil were used.

The paper* describes the design and operation of a laboratory combustion chamber used to study the energy released during the premixed burning phase of diesel combustion. The flow apparatus operates at atmospheric pressure and has the means to provide near quiescent air at temperatures in the range between 800 and 950° K which is the typical temperature range at the end of compression stroke in a diesel engine. A rotary injection pump with a trigger mechanism delivers equal amounts of fuel to an injector, which sprays it into the constantly replenished supply of fresh, hot air for combustion. An infrared radiation detector and a photodiode sensitive to radiation in the visible range of the electromagnetic spectrum monitor the events taking place inside the combustion chamber through a sapphire lens. A beam splitter permits simultaneous observation of the combustion events by both sensors.

Field tests for a variety of fuels on different tractor engines were carried out during the summers of 1981 through 1986. Fuels tested included alkali refined and winterized sunflower oil blended with diesel fuel, crude degummed sunflower oil blended with diesel fuel, high oleic safflower oil blended with diesel fuel, methylester of sunflower oil, or soybean oil. Blends of either 25% vegetable oil and 75% diesel fuel or 50% vegetable oil and 50% diesel fuel were used. Methylesters were not blended with diesel fuel. The manufacturers that participated in the project were John Deere, J.I. Case and Allis Chalmers. The project indicated that farm diesel tractors can be operated on any of the fuels that were tested. Care should be taken, however, since some signs of premature engine problems were observed. In general, continued use of these fuels cannot be recommended at this time.

The paper describes engine modifications, which are proposed to provide a means to overcome the adverse effect of sunflower oil fuel on diesel engines' longevity. The proposed system consists of a dual fuel system and fuel preheater. The dual fuel system was designed to eliminate engine conditions that are responsible for the majority of the problems associated with the use of sunflower oil fuel. Specifically, the dual fuel system will (1) prevent the operation of an engine on alternative fuels at low-load, low-speed conditions, (2) reduce the exposure time of the fuel injection system to the sunflower oil at the excessively high temperature conditions during the transition process from high to light loads, (3) eliminate the conditions (such as cold start-up) at which the fuel temperature is too low for acceptable atomization, and (4) eliminate the exposure of the fuel injection system to sunflower oil during the shut-down period.

This paper presents the evaluation results from the analysis of different blends of fuels using the 13-mode standard SAE testing method. Six high oleic safflower oil blends, six ester blends, six high oleic sunflower oil blends, and six sunflower oil blends were used in this portion of the investigation. Additionally, the results from the repeated 13-mode tests for all the 25/75% mixtures with a complete diesel fuel test before and after each alternative fuel are presented.

The objective of this study is to relate energy absorption characteristics to selected material properties and to establish a methodology that allows one to determine some of the material properties for maximum energy absorption. The finite element program DYNA-3D and its associated pre and post processors were used. The model used is a hollow square column. Five properties of the materials were included in the analysis: (i) Density (ii) Elastic Modulus (iii) Tangent Modulus (iv) Yield Strength, and (v) Poisson Ratio. The Response Surface Method in conjunction with the canonical analysis were employed to locate the optimum or near optimum levels of the properties and then to determine the equation of the response surface in an area near the vector of optimum levels. For the given levels of three out of five material properties used in the study, one can calculate the remaining two material property levels to achieve the near-optimal energy absorption.

This study relates the structural stiffness and kinetic energy of impact (between 34 J and 136 J) to the resulting contact force and duration of force rise for a square tube with wall thickness between 12.7 mm and 25.4 mm. LS-DYNA3D, finite element program was used for the analysis. Two materials, AISI 4340 and AISI 301 steel, are used as examples. Regression equations for predicting the relationship between the structural stiffness, maximum force and duration of force rise are given for each material.

This paper presents the evaluation results from the EMA durability test on 25% high oleic sunflower oil/75% diesel fuel and 25% high oleic safflower oil/75% diesel fuel. The test results from both fuels were compared to the outcome for a standard diesel fuel. The fuels were compared based on the performance and emissions results including; power output, fuel consumption, CO, CO2, NO and HC and the carbon and lacquer residue formation on the internal parts of the engine. The results indicated no significant change in engine performance for the tested fuels, throughout the duration of the investigation. The carbon and lacquer residue formations were within a normal range for both fuels in comparison to the results from the fuel for standard diesel fuel.