Search Results

Two different aluminium alloy materials have been used to produce ventilated brake discs, on one hand, AS17G0.6 hypereutectic alloy and on the other hand, AS7G0.6 reinforced with 20% in wt. of SiC particles. The casting production technique used has been Low Pressure Casting (LPC) and some of the brake discs have been heat treated using a T6 treatment. Once the ventilated brake discs were produced and machined, they were tested in a dynamometer in order to compare the performance under service conditions of the aluminum alloy and grey cast iron (GCI) discs currently used in the market.

The present work compares the tribological properties of ZnO (Zinc Oxide) nanoparticle based lubricant with ZDDP (zinc dialkyl dithiophosphate) based lubricant. The nanolubricant was prepared by mixing the nanoparticles in base oil followed by ultrasonification and ZDDP based lubricant was prepared by mixing ZDDP and stirring with base oil. Base oil used was mineral base oil. Both the lubricants were tested at three different temperatures, loads and roughness values. The test was carried out on AISI 52100 steel samples prepared by wire cutting and were grinded to three different levels of surface roughness. Friction and wear tests were performed using a reciprocating sliding tribo-tester at three different loads and temperatures. Taguchi orthogonal array was used to reduce the number of experiments. SEM, EDS and AFM analysis were carried out to study the surface wear phenomenon.

Damping measurements on vehicle subsystems are rarely straightforward due to the complexity of the dynamic interaction of system joints, trim, and geometry. Various experimental techniques can be used for damping estimation, such as frequency domain modal analysis curve-fitting methods, time domain decay-rate methods, and other methods based on energy and wave propagation. Each method has its own set of advantages and drawbacks. This paper describes an analytical and an experimental comparison between two, widely used loss factor estimation techniques frequently used in Statistical Energy Analysis (SEA). The single subsystem Power Injection Method (PIM) and the Impulse Response Decay Method (IRDM) were compared using analytical models of a variety of simulated simple spring-mass-damper systems. Frequency averaged loss factor values were estimated from both methods for comparison.

The brake friction materials in an automotive brake system play an important role in the overall braking performance of a vehicle. Metal Matrix Composites (MMCs) have been widely investigated and applied due to their advantages of improved strength, stiffness and increased wear resistance over the monolithic alloys in automobile industries. In this paper, Al/B4CP and Mg/B4CP composites were compared to find a suitable candidate material for automotive disk brake application, in terms of wear behavior results of the materials. In addition, the experimental data was also used to model this behavior by identification. The measured tangential force was considered as the input parameter, whereas the weight loss as the output parameter. Preliminary results of this work showed that B4CP addition improved wear resistance of both aluminum and magnesium matrix composites. Additionally, the study pointed out that identified models provide a reliable and cost effective tool for wear prediction.

The effect of rotor alloy composition on thermal conditions in a disc brake system was determined analytically. The three alloys selected were gray cast iron, 356 aluminum, and copper -1% chromium. This study includes calculations of the temperature and heat storage in the various portions of the brake system, as well as the variations of convective heat transfer throughout the system. These computations were made for the transient conditions existing during a series of 60 mph stops (15 ft/sec2 deceleration). The steady-state rotor surface temperature and the thermal gradients were found to decrease with increasing thermal conductivity of the alloys. The rotor surface temperatures for the first two stops were relatively independent of thermal conductivity, but were strongly dependent on heat capacity. Convection was found to occur almost entirely (greater than 90%) from the rotor surface and ventilating passages.

A unique opportunity arose to make a direct comparison of aluminum, sheet molding compound (SMC) and steel using a common hood design. In considering all possible material combinations of inner and outer panels, it was discovered that some of the combinations were incompatible due to material properties. Only the compatible material combinations were considered. Three different joining techniques - welding, bonding and bonded hem flanging - were evaluated. The cost, weight and structural performance of the chosen hood material combinations were established. Areas of further development were identified, including design optimization for specific material combinations.

Various galvanized steels, ZINCROMETAL and cold-rolled steel were painted with automotive-type paints and tested via accelerated, atmospheric and on-vehicle tests. Tests indicate that the ASTM B117 salt fog test and the Kesternich SO2 test do not yield results which are indicative of automotive, in-service corrosion performance. A modified Volvo scab corrosion test was found to offer an accelerated method to accurately predict automotive, in-service corrosion performance. Galvanized steels exhibited corrosion resistance which was far superior to ZINCROMETAL and cold-rolled steel. Thicker zinc coatings on steel were found to offer better corrosion protection to painted substrates.

Accumulation of fuel, water, acids, insolubles, and metals in engine oil is documented and compared for variable-fueled (fuel containing up to 85 percent methanol) and gasoline-fueled vehicles in short-trip service. The oil temperature at which various contaminants are removed is noted. As a consequence of emulsion formation, the viscosity of the oil in the M85-fueled vehicles increased. Due to the presence of gasoline, the viscosity of the oil in the gasoline-fueled vehicles decreased. Equations were developed to explain both the viscosity reduction due to gasoline and the viscosity increase due to emulsion-forming contaminants (water and methanol).

A comparison of various numerical tools and techniques was performed for calculating the lightning indirect effects to composite structures and internal systems. This paper is a summary of the initial comparison results. Detailed results of each technique considered are given in additional separate papers presented during this conference. The modeling considered current distributions over and within composite surfaces and the coupling of current and voltages to internal systems such as wire bundle cables and hydraulic and fuel tubes. The models were compared to each other and to measured data from low level swept continuous wave (LLCW) tests performed on two test fixtures. Other features of the codes such as run time, ease of use, computer requirements, availability of documentation and technical support, etc. are compared as well.

Wheat plants were grown at water potentials in the root zone of -0.4, -3.0, and -5.0 kPa in root modules with various porous membranes through which the nutrient solution was delivered. Root modules contained plants grown during 49 days on different types of porous membranes: ceramic porous tubes with diameters of 10 mm or 22 mm, a porous titanium plate, in a compartment with a porous ceramic tube in perlite and in a 2.5 cm layer of perlite which covered a porous titanium plate. Root modules containing perlite showed much higher dry mass plants in yield than plants in root modules without perlite. A drop in water potential resulted in growth inhibition in all of the modules, especially in the tests without perlite. Design characteristics of the modules significantly affected the root distribution volume. These results may provide additional information in the design of root modules for future space plant growth chambers.

This paper discusses the contribution of instrument panel systems in a European side-impact event. Systems studied include a conventional steel cross-car beam system and a glass-mat thermoplastic (GMT) composite system, evaluated in a body-in-white structure. A thermoplastic composite instrument panel system offers mass, cost, and recycling benefits, but its performance vs. a conventional steel cross-car beam system merited an engineering investigation. The comparison methodology used included a nonlinear dynamic side impact study with a moving, deformable barrier developed according to European Economic Community (EEC) standards. A finite-element model used in this study simulated the body-in-white structure, barrier structure and instrument panel systems. The resulting data include velocity, displacement and energy absorption levels of various components of the respective instrument panel systems.

The results of durability testing of faced metal valves and sialon valves in a heavy duty diesel engine are discussed. An after test SEM analysis of valve face morphology and wear mechanism analysis is used to explain the difference in wear rates. It is concluded that though today's metal valves offer excellent performance for heavy duty applications, ceramics offer potential for extended valve train overhaul life as well as being a more durable material for alternate fuel applications where severe wear and corrosion are a problem.

Hat-sections, single and double, made of steel are frequently encountered in automotive body structural components. These components play a significant role in terms of impact energy absorption during vehicle crashes thereby protecting occupants of vehicles from severe injury. However, with the need for higher fuel economy and for compliance to stringent emission norms, auto manufacturers are looking for means to continually reduce vehicle body weight either by employing lighter materials like aluminum and fiber-reinforced plastics, or by using higher strength steel with reduced gages, or by combinations of these approaches. Unlike steel hat-sections which have been extensively reported in published literature, the axial crushing behavior of hat-sections made of fiber-reinforced composites may not have been adequately probed.

This paper describes the results of a series of fatigue studies relating the lives of several weld geometries. Rotating beam and axially loaded specimens were used. A comparison between steel and plastic (polyvinylchloride scale models is made. Using plastic scale models of welded structures for fatigue life determination is the ultimate goal of this work.

Interest in ductile, tough magnesium alloys has been stimulated by designers seeking lightweight, efficient steering control structures. The simultaneous need for deformable, energy-absorbing components redirected metallurgists to consider the impact behavior of “high-ductility”, AM-series, magnesium alloys. This paper provides a comparison between the “workhorse” AZ91D magnesium alloy and the less-common, AM60B alloy. Specific application to a steering column bracket illustrates the development processes involved in selecting the appropriate alloy.

Atomized iron powder was screened to narrow fractions and annealed. Intermetallic Fe3P powder was blended with the fractions to provide an alloy containing 0.45% phosphorus after sintering. Cores were pressed to a density of 7.4 g/cm3 and sintered at temperatures ranging from 1600°F (870°C) to 2600°F (1430°C) in hydrogen. Magnetic properties were determined from the sintered cores and compared with previous properties measured for iron and hot repressed 0.45% phosphorus iron. It was found that the induction at any density level was approximately 500 gausses (0.05 teslas) lower than for iron. Remanent magnetization was influenced by the size of the pores. If pores were large, remanent magnetization was 8 K gausses (0.8 teslas) and increased to 12 K gausses (1.2 teslas) as the pores become finer. Both maximum permeability and the coercive force were improved when 0.45% phosphorus was added.

A comparison was done of the prediction capabilities for lightning indirect effects of two two-dimensional (2-D) computer codes using two graphite structural test fixtures. The two codes evaluated were an internal Boeing Method-of-Moments code and a commercially available Boundary Element method code. The codes were compared against each other and against test data. The purpose was to evaluate the prediction capabilities of both codes for use in predicting lightning indirect effects on internal components of graphite structure. Since 2-D codes are much easier to use than 3-D codes, they could be widely used in trade studies and design evaluations for lightning indirect effects protection of composite aircraft. The first code, REDIST, is a Method-of-Moments code developed in the 1980’s for use on the B-2. The REDIST code has short run times and is somewhat easier to use than the second code that was investigated.

Continuing pressure to reduce mass and cost of vehicles is driving the development of new high strength steel products with improved combinations of strength and formability. Galvanized, cold rolled dual phase steel products are new alternatives to conventional high strength low alloy (HSLA) steel for strength limited applications in vehicles. These steels have higher tensile strengths than HSLA products with nearly equivalent formability. This paper compares the performance of HSLA and dual phase sheet steel products in a series of drop tower tests. Samples were prepared by stamping the steel sheets into typical rail-type parts using a production-intent die process. The parts were sectioned, and subsequently fabricated into hat-shaped assemblies that were then dynamically crushed by a drop weight. The experiments were designed such that the entire energy input by the drop weight was absorbed by the samples.

It is often said that heavier cars are inherently safer than lighter ones. However, when all cars are built with steel, larger size necessarily implies greater weight, so it is unclear whether the improved safety correlates to the weight or size of the vehicle. Using a publicly available computer model of the Ford Taurus, it was thought that this perception could be tested. The existing steel model, with the addition of a Hybrid III dummy and driver side airbag, was validated against actual crash test data. The structure was converted to aluminum, structural stiffness was calculated, and the steel and aluminum crash simulation results were compared. The aluminum model, utilizing monocoque sheet structure, weld bonded joining, and tailor welded blanks, weighed 200 kg less than the steel model and performed as well.

Nickel-5 Aluminum (95 % Nickel-5 % Aluminum) is widely used in the aircraft engine industry. The excellent adhesive and cohesive strength of the coating, oxidation resistance and machinability make it an ideal material as both a bond coat for subsequent topcoats and as a build up material for dimensional restoration of worn or mismachined components. Plasma spraying has traditionally been the thermal spray process used to apply nickel aluminum, and the technical properties and performance characteristics are well documented. More recently, wire arc sprayed nickel aluminum is becoming widely used as an alternative to plasma spraying due to higher bond strengths, reproducibility, better machinability and more favorable economics. This paper presents the results of a testing program designed to compare the technical properties of arc sprayed versus plasma sprayed Nickel-5 Aluminum coatings.