This paper describes the experimental activity carried out at Aerospace Engineering Department of Politecnico di Milano about energy absorption capability of glass-epoxy RTM specimens, representative of automotive crash front structure sub-components. After the analysis of some automotive crashworthiness aspects, especially relevant to the structural adoption of composite materials, the specimen used and the technological route to produce them are described. Then experimental arrangements, test procedure and measurement technique, relevant to static and crash test are presented. Finally test results, reported in the form of numerical values, diagrams and high-velocity films are shown and critically commented.
The windows of a vehicle have to satisfy the following driver and passenger needs concerning visibility and climate perception both related to active safety: transparency, reluctance, dazzling, glare and diffused light (scattering). All functions are related to visibility and so to the optics of glazing, solar control, deicing, defogging, demisting. The task of material science is to find the multifunctional glasses solving simultaneously problems of visibility, safety and comfort. Particular kind of glasses, colored, wired, coated, electrochromic, liquid crystal, photochromic can be already considered solutions which can operate passively or actively. The example of passive solar control and active heatable coated glasses is shown as a possible practical multifunctional glass very soon.
In order to achieve lean burn engine control system, it is necessary to develop high accuracy air fuel ratio control technology including transient driving condition and lean burn limit expansion technology. This paper describes the following. 1 The characteristics of the transient response of the fuel supply are clarified when various kinds of air flow measuring methods and fuel injection methods are used. 2 To achieve stable combustion in lean mixture, fine fuel droplet mixture, whose diameter is less than 40 μm, needs to be supplied.
Vibration and sound radiation characteristics of bead-stiffened panels are investigated. Rectangular panels with different bead configurations are considered. The attention is focused on various design parameters, such as orientation, depth, and periodicity, and their effects on equivalent bending stiffness, modal density, radiation efficiency and sound transmission. A combined FEA-SEA approach is used to determine the response characteristics of panels across a broad frequency range. The details of the beads are represented in fine-meshed FEA models. Based on predicted surface velocities, Rayleigh integral is evaluated numerically to calculate the sound pressure, sound power and then the radiation efficiency of beaded panels. Analytical results are confirmed by comparing them with experimental measurements. In the experiments, the modal densities of the panels are inferred from averaged mechanical conductance.
An overview of model development for seated occupants is presented. Two approaches have been investigated for modeling the vertical response of a seated dummy: finite element and simplified mass-spring-damper methods. The construction and implementation of these models are described, and the various successes and drawbacks of each modeling approach are discussed. To evaluate the performance of the models, emphasis was also placed on producing accurate, repeatable measurements of the static and dynamic characteristics of a seated dummy.
This paper describes the rattle mechanisms that exist in seat belt retractors and the vehicle acceleration conditions that induce these responses. Three principal sources of rattle include: 1) the sensor, 2) the spool, and 3) the lock pawl. In-vehicle acceleration measurements are used to characterize retractor excitation and are subsequently employed for laboratory testing of retractor rattle. The merits and demerits of two testing methods, based on frequency domain and time domain shaker control, are discussed.
The authors participated in a task force that was required to develop a repeatable, dependable, and reliable test procedure to compare, rate, and evaluate the severity of rattles. The assemblies involved in the study are designed and manufactured by different companies and are tested by different people on test equipment and instrumentation from different suppliers. The challenges therefore, were considerable and involved both the vibration inputs and responses as well as the acoustic responses. At the beginning of this activity, it was observed that different test labs using the same Ford vibration specs were obtaining different sounds from the same test item! Clearly, this was unacceptable and the test methods had to be improved and standardized. This paper focuses on vibration related to rattle testing. The particular assemblies used in this study were seat belt retractors.
In automotive assembly facilities worldwide, many critical vehicle systems such as brakes, power steering, radiator, and air conditioning require the appropriate fluid to function. In order to insure that these critical vehicle systems receive the correct amount of properly treated fluid, automotive manufacturers employ a method called Evacuation and Fill. Due to their closed-loop design, many critical vehicle systems must be first exposed to vacuum prior to being flooded with fluid. Only after the evacuation and fill process is complete will the critical vehicle system be able to perform as specified. It has long been thought, but never proven, that humidity and entrenched fluid were major hindrances to the Evacuation and Fill process. Consequently, Ford Motor Company Advanced Manufacturing Technology Development, Sandalwood Enterprises, Kettering University, and Dominion Tool & Die conducted a detailed project on this subject.
For many years manufacturer’s had to devote considerable work to demonstrate that an aircraft met the specific requirements. The indicator of credibility lies primarily in the award of Type Certification, marked by a Certification of Airworthiness. Since flight test engineering accounts for a major portion of aircraft manufacturer’s controllable cost; the implementation of structured methods and advanced operational procedures will yield the most dramatic single cost savings. The FTIMS/2000™ seamlessly links a complex array of strategic flight test business processes into a logical flow and is used as a true management tool. It is one of the only systems of its kind and is recognized by major aerospace corporations worldwide.
A series of side facing seat impact sled tests were conducted using the SID, EuroSID-1 and BioSID side impact Anthropomorphic Test Dummies (ATDs) at the FAA Civil Aeromedical Institute (CAMI). The tests were performed on a side facing sofa fixture with a rigid bulkhead adjacent to the forward end of the seat. The purpose of the research project was to examine the methods utilized by the automobile industry to assess thoracic injuries due to side impact accidents, and to investigate the potential applicability of these methods for side facing seats and sofas in civil aircraft. Tests were conducted with single and double occupants. The test conditions complied with the 16g 44 f/s horizontal impact specified in 14 CFR 25.562. Various side impact injury criteria were evaluated in the tests, including the Thoracic Trauma Index (TTI), Viscous Criteria (VC), rib deflection and pelvis acceleration.
Ice accumulation on aircraft wings during flight is a dangerous situation. To deal with this problem, current deicing systems either prevent ice accumulation by heating or break the ice layer once it is formed by dynamic motion of a leading edge device such as a boot. These systems may be deficient due to excessive energy requirements or ineffectiveness. In this project, the feasibility of using shape memory alloy (SMA) composite material for deicing purposes is investigated. SMA such as Nitinol wire has an unusual characteristic where it can be trained to generate a compressive strain upon application of an electric current through the wire. Several different versions of two inch radius semi-circular SMA composite specimen were manufactured and tested at Wichita State University. Ice was successfully shed in static icing tests while each of the subsequent versions reduced the power input requirement.
This paper presents a method of detecting aircraft icing by monitoring its effects on aircraft dynamics. This paper shows that uncontrolled icing on control surfaces directly influences control effectiveness. Using data from onboard attitude and navigation sensors via highly computationally efficient algorithms, the control effectiveness is estimated, thereby detecting icing. Using actual flight test data from NASA Lewis Research Center, this paper demonstrates the ability of this method to detect the loss of elevator effectiveness that occurs with uncontrolled horizontal stabilizer icing that could result from a failed deicing boot. The method is generally applicable to loss of control effectiveness due to icing. Icing affects the aerodynamic performance of aircraft by contaminating the aerodynamic surfaces. Without anti-icing equipment icing, if sufficiently severe, can relatively quickly lead to a situation in which controllable flight is impossible.
This paper presents an integrated design/simulation/test approach for evaluating the sound quality of exhaust noise as early as possible in the exhaust system design and development process. A time domain engine/exhaust simulation program is used to calculate the engine order content of the tailpipe radiated noise from an odd fire V-10 exhaust system. Both steady state and transient conditions are simulated and sound files generated for exhaust sound quality evaluation. To increase the realism of played back sounds, the predicted engine orders are mixed with synthesized or recorded background noise for both steady state and transient conditions. These alternative approaches will be described and evaluated for technical feasibility and sound quality.
Increasing concern about the impact of internal combustion engines on the environment has led to ever more stringent emission legislation, and the introduction of more sophisticated equipment to enable the requirements to be achieved. One way of improving the emissions from direct injection (DI) diesel engines is to use multi-stage fuel injection, and an investigation performed on such a system is reported in this paper. In this case, the multi-stage fuel injector caused an increase in the exhaust smoke at low load, and an in-cylinder photographic technique was used to examine why this occurred. A multi-stage fuel injector with a VCO nozzle was fitted to a small, high-speed, direct injection diesel engine fitted with a transparent piston for optical access. The combustion process was filmed using a high-speed 16 mm cine camera, and the fuel injection process was illuminated by a high power, copper-vapour laser.
Four 1998 Mitsubishi Carismas, two equipped with direct injection (GDI) and two with port fuel injection engines (PFI) were tested in a designed experiment to determine the effect of mileage accumulation cycle, engine type, fuel and lubricant type on engine wear and engine oil performance parameters. Fuel types were represented by an unadditised base fuel meeting EEC year 2000 specifications and the same base fuel plus synthetic deposit control additive packages. Crankcase oils were represented by two types (1) a 5W-30 API SJ/ILSAC GF-2 type engine oil and (2) a 10W-40 API SH/CF ACEA A3/ B3-96 engine oil. The program showed that specific selection of oil additive chemistry may reduce formation of intake valve deposits in GDI cars.. In general, G-DI engines produced more soot and more pentane insolubles and were found to be more prone to what appears to be soot induced wear than PFI engines.
Fleet managers need a tool to assist them in assessing their need to comply with EPAct and to provide them with the ability to obtain information that will allow them to make alternative fuel vehicle purchasing decisions. This paper will describe the Web-based tool that will inform a fleet manager, based on their geographic location, the type of fleet they own or operate, and the number and types of vehicles in their fleet, whether or not they need to meet the requirements of EPAct, and, if so, the percentage of new vehicle purchases needed to comply with the law. The tool provides detailed specifications on available OEM alternative fuel vehicles, including the purchase cost of the vehicles, fuel and fuel system characteristics, and incentives and rebates surrounding the purchase of each vehicle. The full set of federal, state, and local incentives is made available through the tool, as well as detailed access to refueling site and dealership locations.
Early stage combustion systems, with lean homogeneous charge compression ignition (HCCI), have been studied, with the intent to decrease the pollutant emission characteristics of DI diesel engines. Early stage combustion enables drastic reductions in both nitrogen oxides (NOx) and smoke emission, but the operating load range is restricted, due to combustion phenomena, such as unsteady combustion and knocking. In this study, we explored the possibility of broadening the operating load range in HCCI and reducing pollutant emissions using Dimethyl Ether (DME) fumigated through the intake pipe. However, the improvements in load range were found to be less than 0.1 MPa in brake mean effective pressure (BMEP), even when compression ratios were reduced and Methane with high octane number was mixed. Therefore, a DME premixed charge could be used only at light loads. At heavier loads a hybrid fuel system with a DME premixed charge and diesel fuel injection is necessary.
“Gas-to-liquids” catalytic conversion technologies show promise for liberating stranded natural gas reserves and for achieving energy diversity worldwide. Some gas-to-liquids products are used as transportation fuels and as blendstocks for upgrading crude-derived fuels. Methylal (CH3-O-CH2-O-CH3), also known as dimethoxymethane or DMM, is a gas-to-liquid chemical that has been evaluated for use as a diesel fuel component. Methylal contains 42% oxygen by weight and is soluble in diesel fuel. The physical and chemical properties of neat methylal and for blends of methylal in conventional diesel fuel are presented. Methylal was found to be more volatile than diesel fuel, and special precautions for distribution and fuel tank storage are discussed. Steady state engine tests were also performed using an unmodified Cummins B5.9 turbocharged diesel engine to examine the effect of methylal blend concentration on performance and emissions.
During 1998, the US Federal authority introduced a requirement for vehicles powered by heavy duty diesel engines that NOx emissions shall be less than 4 g/bhp.h. This represents a 20% reduction over current levels and has prompted significant further hardware changes. As a result of these increasingly tighter NOx emission constraints, soot loading of diesel engine lubricants - due to retarded fuel injection, is becoming an ever more significant issue in crankcase lubricant formulation. For this reason, increased understanding is required of the mechanism of soot particle aggregation and resultant aggregate morphology - together with the likely consequences for the performance of soot-laden lubricants, for viscosity increase, filter blocking, sludging and (directly or indirectly) - soot-induced wear. We describe here a combined experimental and simulation approach to screening formulated lubricants and characterising soot aggregate structures.