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It is well known that the ride quality of trucks is much harsher than that of automobiles. Additionally, truck drivers typically drive trucks for much longer duration than automobile drivers. These two factors contribute to the fatigue that a truck driver typically experiences during long haul deliveries. Fatigue reduces driver alertness and increases reaction times, increasing the possibility of an accident. One may conclude that better ride quality contributes to safer operation. The secondary suspensions of a tractor have been an area of particular interest because of the considerable ride comfort improvements they provide. A gap exists in the current engineering domain of an easily configurable high fidelity low computational cost simulation tool to analyze the ride of a tractor semi-trailer. For a preliminary design study, a 15 d.o.f. model of the tractor semi-trailer was developed to simulate in the Matlab/Simulink environment.

The unmanned roller is one of the most popular construction vehicles, for which the accurate path-following is one of the most important control task. The dual-antenna Global Positioning System (GPS), usually mounted on the top of the cabin and the front drum separately, is used to approximately measure the position and heading direction at the contact patch between the wheel and the road. However, in the presence of large variation in the attitude of the roller, caused by the uneven construction site, there is bias in position and heading measurement due to the wobble of the roller. Obviously, this introduces several disturbances to the path-following control. In this paper, the Attitude Heading Reference System (AHRS) is used to measure the attitude information thereby corrects the position and heading of the roller measured by GPS only.

This SAE Recommended Practice establishes uniform test procedures and performance requirements for engine-off heating, ventilation, and air conditioning (HVAC) systems in order to achieve driver thermal comfort in both winter and summer rest periods. This specification will apply to heavy trucks with and without sleeper compartments, including but is not limited to Class 6, 7, and 8 powered vehicles.

Overall cycle time and prototype testing are significantly decreased by assessment of cooling module performance in the design stage itself. Hence, Front End Cooling and Thermal Management are essential components of the vehicle design process. Performance of the cooling module depends upon a variety of factors like frontal opening, air flow, under-hood sub-systems, module positioning, front grill design, fan operation. Effects of design modifications on the engine cooling performance are quantified by utilizing computational fluid dynamics (CFD) tool FluentTM. Vehicle frontal configuration is captured in the FE model considering cabin, cargo and underbody components. Heat Exchanger module is modelled as a porous medium to simulate the fluid flow. Performance data for the Heat Exchanger module is generated using the 1D KuliTM software. In this paper, CFD simulation of Front End Cooling is performed for maximum torque and maximum power operating conditions.

This SAE Part Standard covers selected metric screws, hex bolts, and nuts manufactured in accordance with American Society for Testing and Materials (ASTM) and SAE fastener standards. This document covers fastener materials often used in ship systems and equipment but its use may be applied wherever fasteners of the covered materials are used. This document permits the fasteners to be identified and ordered by a part or identifying number (PIN) as defined in this document.

This SAE Part Standard covers selected metric screws, hex bolts, and nuts manufactured in accordance with American Society for Testing and Materials (ASTM) and SAE fastener standards. This document covers fastener materials often used in ship systems and equipment but its use may be applied wherever fasteners of the covered materials are used. This document permits the fasteners to be identified and ordered by a part or identifying number (PIN) as defined in this document.

This Hydrospace Information Report (HIR) identifies the general environmental considerations for the design, development, evaluation, and testing of advanced surface craft, submersible vehicles, and other marine craft. This HIR provides criteria on the environmental limits within which marine vehicles, related components, and associated equipment should operate satisfactorily and reliably.

This recommended practice provides a procedure for measuring and documenting the aerodynamic performance in a full-scale wind tunnel of passenger vehicles, i.e., mass-produced cars and light-duty trucks intended primarily for individual consumers. Testing or numerical modeling of pre-production and/or reduced-scale models is outside the scope of this document. Aerodynamic development procedures, i.e., methods to improve or optimize aerodynamic performance, are also excluded. It is well-known that aerodynamic performance results depend significantly on vehicle content and loading, as well as the wind tunnel itself (type, scale, and simulation qualities of the wind tunnel). Publication of non-standard test results causes unnecessary additional development work and incorrect perception of a vehicle’s anticipated aerodynamic performance by government, academia, and the general public.

The drag reduction device of a bluff-body was developed by slanting the rear underbody as a hip-up shape and adding flaps to the rear-end. The experiments were conducted in an open-jet low turbulence wind tunnel while the bluff-body model was varied in both slant angles and rear flap configurations. Drag forces, surface pressures around the body, and the velocity distribution in wake were measured experimentally. The surface flow at the underbody was visualized by the oil-paint method. Force measurements showed that an underbody slant with rear flaps reduced the drag force. The most effective setting occurred when the underbody was slanted three degrees with the enclosure that had the upper, side and lower flaps. In spite of the negative pressure and the trailing vortex at the underbody, the underbody slant was useful to diminish the velocity defect in wake, which led to an increase in the rear-end pressure.

The engineering process in the development of commercial vehicles is facing more and more stringent emission regulations while at the same time the market demands for better performance but with lower fuel consumption. The optimization of aerodynamic performance for reduced drag is a key element for achieving related performance targets. Closely related to aerodynamics are wind noise and cabin soiling and both of them are becoming more and more important as a quality criterion in many markets. This paper describes the aerodynamic and aero-acoustic performance evaluation of a Dongfeng heavy truck using digital simulation based on a LBM approach. It includes a study for improving drag within the design of a facelift of the truck. A soiling analysis is performed for each aerodynamic result by calculating the accumulation of particles emitted form the wheels on the cabin. One of the challenges in the development process of trucks is that different cabin types have to be designed.

This paper presents a verification of the effectiveness of an image processing method, used to reduce the inconsistent speed perception caused by using the camera images in conjunction with side-view mirrors. Vision assistance technology using cameras is widely used in practical applications today. However, speed and distance perceived with camera images may differ from those viewed directly or viewed with conventional side-view mirrors. That is particularly evident in wide-angle camera images, and can easily cause a sense of discomfort experienced by the driver. A Side View Camera (SVC) shows images rearward and to the side that include the blind spots of side-view mirrors on an onboard display. It is a system to compensate side-view mirrors, broadening the driver's field of view to eliminate bind spots. SVC is used in conjunction with the side-view mirrors.

Although considerable efforts have been made with respect to the reduction of fuel consumption of trucks during the last decades, the diminishing natural resources as well as the evolution of the truck traffic require continuous improvements in the field of aerodynamics. Indeed, the forces generated by the air on the trucks may originate, depending on weather, road type, truck type, dimension, etc., up to 50% of the fuel consumption. In order to analyze the influence of proportion variations (mainly related to the length) and add-on devices on the aerodynamic performance of a truck, a representative model was first generated. This simplified geometry of a tractor-trailer was based on the geometrical data of six European OEMs: Daimler, Iveco, and MAN (tractors), Kögel, Krone and Schmitz Cargobull (trailers). The model included a reduced level of details (exterior mirrors, wheels, simplified underbody and engine block).

Aerodynamic design and thermal management are some of the most important tasks when developing new concepts for the flow around tractor-trailers. Today, both experimental and numerical studies are an integral part of the aerodynamic and thermal design processes. A variety of studies have been conducted how the aerodynamic design reduces the drag coefficient for fuel efficiency as well as for the construction of radiators to provide cooling on tractor-trailers. However, only a few studies cover the combined effect of the aerodynamic and thermal design on the air temperature of the under hood flow [8, 13, 16, 17, 20]. The objective of this study is to analyze the heat transfer through forced convection for a scaled Cab-over-Engine (CoE) tractor-trailer model with under hood flow. Different design concepts are compared to provide low under hood air temperature and efficient cooling of the sub components.

As part of a system for structural health monitoring, it is required to determine the spatial and temporal distributions of vertical loads arising from heavy trucks driven on flexible bridge structures. An instrumented truck is used to generate the input loads and estimate the load time histories. The truck can carry a range of sensors; however direct measurement of vertical tire loads between the tires and the structure is not considered realistic. The dynamic loads are to be estimated from the sensor outputs. These are affected by both truck and bridge dynamics and these must be accounted for within the load estimation process. Estimation may be susceptible to many factors including static mass distribution, vehicle longitudinal motion, variations in lateral position on the bridge, as well as any surface unevenness.

The present numerical analysis aims at studying the effect of changes in profile of truck-trailer on aerodynamic drag and its adverse effect on fuel consumption. The numerical analysis is carried out using commercial CFD software, ANSYS Fluent, with k-ω Shear tress transportation (SST) turbulence model. In present study four models of truck were analysed, including baseline model at different Reynolds numbers, namely 0.5, 1, 1.5 and 2 million. In order to enhance fuel consumption, various profile modifications have been adapted on baseline truck-trailer model by adding a spoiler and bottom diffuser at the rear of the truck, by providing vortex generator at the rear top of the truck and by adding boat tail at the end of trailer. The comparison has been done with respect to coefficient of drag, coefficient of pressure, pressure contours, and velocity vectors between all four cases.

Glare from the headlights of following vehicles which is reflected in rearview mirrors can be a significant problem. Glare can cause driver discomfort, it can diminish the driver's ability to see, and it can cause driver fatigue, particularly during prolonged night-time driving common for many professional drivers. Conventional rearview mirrors, such as silvered and chromed mirrors, offer only one reflectivity level. Variable reflectance mirrors, such as those utilizing electrochromic and liquid crystal technology, are capable of multiple reflectance levels. With variable reflectance, the driver can select a high reflectivity level during daytime driving or when reversing into loading docks, and can select a reduced dimmer reflectance level when driving during glaring conditions. This paper briefly reviews the principal technologies available for variable reflectance mirrors and outlines their performance as glare-reducing mirrors.

This study attempts to predict the effect of visual impairment from simulated levels of splash and spray on target vehicle identification distances. Five levels of hand held spray simulation frames were used to compare image digitization methods with visual performance (Snellen acuity or contrast sensitivity) assessment to predict a drivers ability to identify an oncoming target vehicle. The image digitization process was found to be highly correlated with actual target vehicle identification distances. Additionally, very high correlations were found between Snellen acuity and contrast sensitivity and identification distance. There did not seem to be any great difference in predictive power of either method of visual performance assessment over the other.

When truck tires have a deformation such as radial runout, flat spot, and abnormal wear as a result of panic braking, they affect vehicle vibration in the form of displacement input whose spectrum involves higher order terms of tire revolution. While a truck has vibration modes of frame bending as well as pitching and unsprung-mass viberation in the input frequency range, the tire displacement input induces vehicle vibration as a combination of these modes. Results of calculations and experiments of a 4x2 medium-duty truck are analyzed and an example of means for improving ride comfort is described in this paper.

Laser machining is an effective material removal process for types of materials which are difficult to machine mechanically, such as hardened alloys, ceramics, and composites. Since laser machining is a thermal process, its effectiveness depends on the thermal rather than the mechanical properties of a material. This paper discusses a concept for performing three-dimensional (3-D) laser machining using two laser beams. This concept aims at improving the material removal rate and energy efficiency of laser machining. Furthermore, the kinematic aspects of 3-D laser machining are discussed. Results for 3-D laser machining of metals, ceramics and composites are presented and compared with conventional machining methods.

A machine vision system was developed to identify and locate harvestable spears of asparagus. An image acquisition vehicle was fabricated to videotape portions of asparagus rows from a commercial production field. Images were acquired using a monochrome CCD camera. The detection of reflectance properties of asparagus was enhanced by using optical bandpass filters for near-infrared radiation. Videotaped segments acquired in the field were analyzed. Image processing techniques based on geometrical characteristics of asparagus spears were used to identify and locate harvestable spears in the images. Harvestable spears measured in the field were compared to those found by machine vision. The vision system correctly identified from 86 to 97% of the harvestable spears in six 15 m row segments analyzed. The uncertainty in the location of spears was within a 2.97 by 5.39 cm window with 95% confidence.