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.
This paper reviews the interactions between vehicle and road designers, particularly in the area of fuel consumption related to traffic management. The need for increased interaction between vehicle and road designers is illustrated in the cases of truck traffic performance, truck technology, information technology in cars, car performance, speed control and road information. Fuel consumption models developed at the Australian Road Research Board are described for the purposes of traffic management analysis for intersections, road links and broad urban studies. These models are a major step towards appropriate choice of traffic control systems, but need accurate estimates of vehicle performance characteristics in real traffic.
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.
This paper explores the need for human factors and error management within the context of the general and corporate aviation environments. It discusses strategies currently employed in other segments of the aviation industry and how they might be utilized in the corporate and general aviation arenas. It also relates research findings and program successes experienced within the airline industry and makes recommendations as to how a consortial effort by industry organizations might be utilized to employ these strategies in corporate and general aviation operations.
While majority of the airlines are struggling to implement macro human factors principles in their maintenance activities, at least eleven corporate aviation departments (CADs) in the country are showing signs of success. The implementation philosophy of these CADs differs from others, and from the airlines in one fundamental aspect: it enforces a behavior change rather than an attitude change among the CAD employees. Consequently, they strive to achieve an employee behavior which is consistent within and across their flight operations, maintenance, and management functions. Ethnographic research was conducted at one of the eleven eligible sites to develop a theoretical model which is representative of the structure, the strategy, and the processes used by these aviation departments to implement macro human factors principles in aviation maintenance. This model was then tested at three other CADs that have a implemented similar approach.
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 describes research to analyze widespread fatigue damage in lap joints. The particular objective is to determine when large numbers of small cracks could degrade the joint strength to an unacceptable level. A deterministic model is described to compute fatigue crack growth and residual strength of riveted panels that contain multiple cracks. Fatigue crack growth tests conducted to evaluate the predictive model are summarized, and indicate good agreement between experimental and numerical results. Monte Carlo simulations are then performed to determine the influence of statistical variability on various analysis parameters.
This paper describes a method to determine an objective measure of disturbing sounds of automotive exhaust noise (e.g. booming noise, whistle, flow noise,…). First, a disturbing sound catalogue is established. Then the approach used to make the different disturbing sounds measurable is presented. By making the perception of the disturbing sounds objective, it becomes easy to determine when they appear and to what extent. Finally, the contribution of this research in the framework of the global integration of sound quality in the design process of exhaust systems will be discussed.
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.