Mathematical and Computer Simulation of Hex Head Screws for Implementation on a 3D Printer

In this paper, based on the R-functions theory, methods have been developed and equations have been constructed for the 3D printing of hex-head screws with Bristol, Pentalobe, Polydrive and other types of screw slots. Such screws are used both in personal computers and other high-end equipment. The Bristol slot has four or six radial grooved beams. The advantage of the design of this slot is the correct perpendicular, rather than tangential, vector of force application when the slot is rotated by a tool, which minimizes the risk of stripping out the slot. For this reason, the Bristol slot is used in soft metal screws. Compared to the internal hex, the Bristol slot allows a noticeably higher torque, only slightly higher than that of the Torx slot. This type of slot is used in aviation, high-end telecommunications equipment, cameras, air brakes, agricultural equipment, astronomical equipment, and foreign military equipment. Variations with a pin in the center are found in game consoles to prevent the use of a flat-blade screwdriver as an improvised key. The Pentalobe slot is a five-point slot designed by Apple and used in its products to limit unauthorized disassembly. It was first used in mid 2009 to mount MacBook Pro batteries. Its miniature version was used in the iPhone 4 and later models, in the MacBook Air (available since late 2010 models), and the MacBook Pro with Retina screens. The Polydrive slot is a starlike slot with rounded star points, used in the automotive industry for applications requiring high tightening torque. The Torq-set slot is a cross slot for fasteners requiring high tightening torque. The grooves are slightly offset, not intersecting at one point. Fasteners with this type of slot are used in military aviation, for example, in E-3, P-3, F-16, Airbus, Embraer, and Bombardier Inc. The Phillips Screw Company owns the trademark and manufactures fasteners with this type of slot. The slot design standards are National Aerospace Standard NASM 3781 and NASM 4191 for the ribbed version. The resulting equations for the surfaces of screws were checked during the modeling of the screws before 3D printing. The 3D printing technology allows us to reduce the cost and labor intensity of manufacturing products, including complex slot screws. The analytical recording of designed objects makes it possible to use alphabetic geometric parameters, complex superposition of functions, which, in turn, allows us to quickly change their design elements. The positivity property of the constructed functions at the internal points of an object is very convenient for the implementation of 3D printing.

Research of the process of distributing the middle part of tubular blanks

A significant problem in the aircraft industry remains the production of reliable hydro-gas systems, such as flight control, landing gear retraction and release, wheel turn control of the front landing gear, control of air brakes and spoilers, engine thrust reversal control, et al., providing a high degree of performance and reliability. The article discusses the technological processes of manufacturing parts for hydro-gas systems of aircraft. Research has been carried out on the expansion of the middle part of thin-walled tubular billets by cold plastic deformation, which showed that the most dangerous is the middle part of the considered part of the billet, where there are significant tensile stresses. The reduction in tensile stresses that occurs when creating an ice retainer allows to increase in the expansion ratio. The application of new types of working bodies is proposed for transferring pressure to the deformation zone.

BALANCING AN AIRCRAFT WITH SYMMETRICALLY DEFLECTED SPLIT ELEVATOR AND RUDDER DURING SHORT LANDING RUN

This article investigates methods for balancing aircraft during short straight-line landing run realized by employing split rudder and elevator as air-brakes after touchdown. For standard atmospheric and runway conditions, directional and longitudinal balance equations for aircraft of conventional configuration such as Il-86 are presented. Methods depend on operational and mechanical approaches, where the first requires manual or automatic trim of shortly peaking small pitching, yawing, and rolling moments using dynamic forces while the second suggest some re-design of elevator and rudder control channels to limit deflection angles. The paper describes in detail each method disadvantages and suggests the adoption of automatic operational approach due to less required system modifications and piloting skills.

Integrating Non-Friction-Based Braking Technology into Locomotives to Improve Train Efficiency, Durability, and Safety

While frictional braking is an intuitive method by which to slow vehicles, it is also a costly braking method due to the fact that frictional brakes wear down due to frequent use and high quantities of friction. On trains, this problem is worse because of their constant use and because heavier objects require stronger braking forces. The objective is to improve locomotive performance by developing a braking system that utilizes non-frictional braking technology to cut these costs and yield safer, more durable brakes. This project is directed towards dieselelectric3 locomotives with air brakes, as engineers can design blended braking systems that integrate non-frictional braking into these braking systems. The candidate solutions include regenerative, rheostatic, and hydrodynamic braking, two of which use magnetic fields, and the third of which uses fluid drag forces. Regenerative braking is the proposed solution due to its ability to harness and use electricity during braking. Project success would contribute to railway company success by reducing expenses spent on air brakes; it would also contribute to locomotive manufacturer success because the product will likely become a popular technology. Finally, it would benefit the environment by reducing the external energy required by the railway network. Keywords: Locomotive, braking, non-frictional, regenerative, rheostatic, hydrodynamic, diesel-electric

Drag Management in High Bypass Turbofan Nozzles for Quiet Approach Applications

The feasibility of a drag management device that reduces engine thrust on approach by generating a swirling outflow from the fan (bypass) nozzle is assessed. Deployment of such “engine air-brakes” (EABs) can assist in achieving slower and/or steeper and/or aeroacoustically cleaner approach profiles. The current study extends previous work from a ram air-driven nacelle (a so-called “swirl tube”) to a “pumped” or “fan-driven” configuration and also includes an assessment of a pylon modification to assist a row of vanes in generating a swirling outflow in a more realistic engine environment. Computational fluid dynamics (CFD) simulations and aeroacoustic measurements in an anechoic nozzle test facility are performed to assess the swirl-flow-drag-noise relationship for EAB designs integrated into two NASA high-bypass ratio (HBPR), dual-stream nozzles. Aerodynamic designs have been generated at two levels of complexity: (1) a periodically spaced row of swirl vanes in the fan flowpath (the “simple” case), and (2) an asymmetric row of swirl vanes in conjunction with a deflected trailing edge pylon in a more realistic engine geometry (the “installed” case). CFD predictions and experimental measurements reveal that swirl angle, drag, and jet noise increase monotonically but approach noise simulations suggest that an optimal EAB deployment may be found by carefully trading any jet noise penalty with a trajectory or aerodynamic configuration change to reduce perceived noise on the ground. Constant speed, steep approach flyover noise predictions for a single-aisle, twin-engine tube-and-wing aircraft suggest a maximum reduction of 3 dB of peak tone-corrected perceived noise level (PNLT) and up to 1.8 dB effective perceived noise level (EPNL). Approximately 1 dB less maximum benefit on each metric is predicted for a next-generation hybrid wing/body aircraft in a similar scenario.

Development of Diagnostic Algorithms for an Air Brake System: Theory and Implementation

In this paper, we consider the problem of designing an algorithm for estimating the stroke of a pushrod of the air brake system. The stroke of pushrod directly relates to the braking force available at the wheels and also affects the response time. The longer the stroke, the volume available for expansion is larger and correspondingly, the response is slower. The stroke depends on the clearance between the brake pad and the drum, which can vary due to variety of factors such as thermal expansion of drum and mechanical wear. Typical safety inspections of air brakes include the measurement of the stroke of the pushrod of each brake chamber. Regulations on trucks such Federal Motor Vehicle Safety Standard (FMVSS) 121 require the inspection to be carried out at 90 psi supply pressure and at full brake application. The evolution of the brake pressure depends on the stroke of the pushrod and the area of the treadle valve, which is controlled by the driver. The treadle valve meters compressed air from the supply reservoir to the brake chamber. The proposed scheme requires the measurement of pressure and a model for predicting the evolution of brake chamber pressure in response to full application of the brake (brake pedal is fully depressed). We experimentally corroborate the effectiveness of the proposed algorithm.

Drag Management in High Bypass Turbofan Nozzles for Quiet Approach Applications

The feasibility of a drag management device that reduces engine thrust on approach by generating a swirling outflow from the fan (bypass) nozzle is assessed. Deployment of such “engine air-brakes” (EABs) can assist in achieving slower and/or steeper and/or aero-acoustically cleaner approach profiles. The current study extends previous work from a ram air-driven nacelle (a so-called “swirl tube”) to a “pumped” or “fan-driven” configuration, and also includes an assessment of a pylon modification to assist a row of vanes in generating a swirling outflow in a more realistic engine environment. Computational fluid dynamics (CFD) simulations and aero-acoustic measurements in an anechoic nozzle test facility are performed to assess the swirl-flow-drag-noise relationship for EAB designs integrated into two NASA high-bypass ratio (HBPR), dual-stream nozzles. Aerodynamic designs have been generated at two levels of complexity: (1) a periodically spaced row of swirl vanes in the fan flowpath (the “simple” case), and (2) an asymmetric row of swirl vanes in conjunction with a deflected trailing edge pylon in a more realistic engine geometry (the “installed” case). CFD predictions and experimental measurements reveal that swirl angle, drag, and jet noise increase monotonically, but approach noise simulations suggest that an optimal EAB deployment may be found by carefully trading any jet noise penalty with a trajectory or aerodynamic configuration change to reduce perceived noise on the ground. Constant speed, steep approach flyover noise predictions for a single-aisle, twin-engine tube-and-wing aircraft suggest a maximum reduction of 3 dB of peak tone-corrected perceived noise level (PNLT) and up to 1.8 dB effective perceived noise level (EPNL). Approximately 1 dB less maximum benefit on each metric is predicted for a next-generation hybrid wing/body aircraft in a similar scenario.