Effect of Material and Lubrication Conditions on the Underhead Frictional Response in High Strength Socket-Head Screws

2020 ◽  
Author(s):  
Dario Croccolo ◽  
Massimiliano De Agostinis ◽  
Stefano Fini ◽  
Giorgio Olmi ◽  
Francesco Robusto ◽  
...  
Keyword(s):  
Tribological Behavior ◽  
High Strength ◽  
Design Parameters ◽  
Bolted Joint ◽  
Lower Strength ◽  
Coefficient Estimation ◽  
Experimental Campaign ◽  
Proper Design ◽  
Lubrication Conditions ◽  
Current Operating

Abstract The present paper investigates the influence of several design parameters on the frictional response at the underhead in a bolted joint, involving high strength socket-head screws: M8 class 14.9 with black oxidization coating. The experimentation deals with different underhead materials (Steel, Aluminium), lubrication conditions (dry, lubricated) and repeated tightening operations. The awareness of the actual friction coefficients, depending on the current operating parameters, is a useful tool, to support the most proper design of a bolted joint. The experimental campaign has been run by a testing rig for friction coefficient estimation, complying with the recommendations by International Standard ISO 16047 and the automotive Standard VW01131-1 in order to consider the effect of the tightening speed normally adopted in the automotive field. The axial preload generated upon tightening induces a high pressure on the remarkably small underhead surface of the utilized high strength socket-head screws and is therefore likely to affect the tribological response. Consequently, some differences may be expected with respect to the tribological behavior of screws belonging to lower strength grades. This is particularly true, when tightening is done without bearing lubrication, and through several repeated assembly-disassembly operations. The collected data have been processed by the tools of ANOVA and F-Test, in order to assess the significance of each factor, as well as related interactions.

Experimental Investigation on the Friction Coefficients for Different Materials, Lubrication Conditions and Coatings in Bolted Joints

2020 ◽  
Author(s):  
Dario Croccolo ◽  
Massimiliano De Agostinis ◽  
Stefano Fini ◽  
Giorgio Olmi ◽  
Francesco Robusto ◽  
...  
Keyword(s):  
Bolted Joints ◽  
Design Parameters ◽  
Bolted Joint ◽  
Treatment Change ◽  
Friction Coefficients ◽  
Actual Application ◽  
Iron Aluminum ◽  
Torque Wrench ◽  
Zinc Coatings ◽  
Lubrication Conditions

Abstract The present paper investigates the influence of several design parameters on the frictional response of a bolted joint, involving screws from strength grades 8.8 to 12.9, with black oxidization coating or zinc coatings. The experimentation deals with different underhead and nut materials (cast iron, aluminum), lubrication conditions (dry, lubricated, two different threadlockers: medium and strong), roughness condition in the underhead (cast, machined, painted, underhead washers) and cosidering also the effect of repeated tightenings. The friction coefficients of the actual application, retrieved based on the relevant operating parameters, are needed to support a correct design. The experimentation has been carried out by a purposely developed specimen, consisting of two parts: an instrumented sleeve, with a double array of strain gauges capable of sampling both the axial preload and the underhead torque, and interchangeable underhead washers. The testing apparatus is provided with a device which allows preventing undesired rotation of the washers. The washer material and surface treatment change among the different specimen sets. The tightening torque is applied by means of a 10-120Nm digital torque wrench. The collected data have been processed by the tools of ANoVa. Such tools allowed assessing the significance of each factor, as well as related interactions.

JESSOP JS17Cr-4Ni

Alloy Digest ◽  
1982 ◽  
Vol 31 (7) ◽  
Keyword(s):  
Mechanical Properties ◽  
Corrosion Resistance ◽  
Food Processing ◽  
Precipitation Hardening ◽  
High Strength ◽  
Heat Treating ◽  
Steel Company ◽  
Lower Strength ◽  
Nickel Copper ◽  
Short Time

Abstract JESSOP JS17Cr-4Ni is a martensitic, precipitation-hardening chromium-nickel-copper stainless steel. It provides an excellent combination of high strength and hardness, short-time low-temperature precipitation hardening and good mechanical properties at temperatures up to 600 F (316 C). Its corrosion resistance is quite good but inferior to lower strength grades produced for corrosion-resistance applications. JS17Cr-4Ni is used widely for critical applications in the aerospace, chemical, food processing and other industries. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness and fatigue. It also includes information on corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: SS-412. Producer or source: Jessop Steel Company.

The Fatigue Behaviour of a High Strength CrNi-Steel Regarding Fretting Fatigue

2012 ◽  
Author(s):  
Thomas Christiner ◽  
Johannes Reiser ◽  
István Gódor ◽  
Wilfried Eichlseder ◽  
Franz Trieb ◽  
...  
Keyword(s):  
High Strength ◽  
Contact Problems ◽  
Fatigue Behaviour ◽  
Fretting Fatigue ◽  
Service Performance ◽  
Fatigue Properties ◽  
Material Behaviour ◽  
Reliable Prediction ◽  
Damage And Failure ◽  
Lubrication Conditions

In many assemblies of moving components, contact problems under various lubrication conditions are lifetime-limiting. There, relative motion of contacting bodies, combined with high loads transmitted via the contact surface lead to fretting fatigue failure. For a reliable prediction of in service performance load type, different damage and failure mechanisms that may be activated during operation have to be known. In this contribution selected results of a currently conducted research project are presented. The aim of this study was to examine the material behaviour of a surface stressed steel. The influence of the fretting regime on fatigue properties has been investigated.

DESIGN PARAMETERS SELECTION OF SPRINGBACK EFFECT IN AIR-V BENDING USING TAGUCHI APPROACH ON ADVANCE HIGH STRENGTH STEEL-DP590

2015 ◽  
Vol 76 (3) ◽  
Author(s):  
Shahrul Azam Abdullah ◽  
Muhamad Sani Buang ◽  
Juri Saedon ◽  
Hashim Abdullah
Keyword(s):  
Plate Thickness ◽  
High Strength Steels ◽  
High Strength ◽  
Design Parameters ◽  
Optimum Level ◽  
Advanced High Strength Steels ◽  
Parameters Selection ◽  
Bending Process ◽  
Punch Radius ◽  
Evaluation Problem

Advanced High Strength Steels (AHSS) are increasingly utilized especially in automotive industry. However, forming of AHSS is challenging particularly in prediction of springback effect caused by material properties, tools and dies parameters, work material and bending technique factors. An air V-bending process was chosen as an evaluation problem because it showed larger springback effect. This paper presents an optimization to predict the influence of various parameters on springback of sheet metal in air V-bending process using Taguchi method (TM). The experimental study was conducted on DP590 sheets with plate thickness of 1 and 2 mm under different process parameters such as punch radius, die radius, die gap and punch travel. A significant level of springback parameters was further described by using the analysis of variance (ANOVA). It showed that the contribution percentage of each factor to springback was calculated to optimum level and the significant levels of entire factor were observed. The thickness of material, die width, punch travel and punch radius were found to be the most significant factor affecting springback while die radius is insignificant. 

scholarly journals Active Vibration Control of Launch Vehicle on Satellite Using Piezoelectric Stack Actuator

2018 ◽  
Author(s):  
Mehran Makhtoumi
Keyword(s):  
Vibration Control ◽  
Vibration Suppression ◽  
Virtual Work ◽  
Active Vibration Control ◽  
High Strength ◽  
Launch Vehicle ◽  
Design Parameters ◽  
Control Analysis ◽  
Active Vibration ◽  
Piezoelectric Stack Actuator

Satellites are subject to various severe vibration during different phases of flight. The concept of satellite smart adapter is proposed in this study to achieve active vibration control of launch vehicle on satellite. The satellite smart adapter has 18 active struts in which the middle section of each strut is made of piezoelectric stack actuator. Comprehensive conceptual design of the satellite smart adapter is presented to indicate the design parameters, requirements and philosophy applied which are based on the reliability and durability criterions to ensure successful functionality of the proposed system. The coupled electromechanical virtual work equation for the piezoelectric stack actuator in each active strut is drived by applying D'Alembert's principle. Modal analysis is performed to characterize the inherent properties of the smart adapter and extraction of a mathematical model of the system. Active vibration control analysis was conducted using fuzzy logic control with triangular membership functions and acceleration feedback. The control results conclude that the proposed satellite smart adapter configuration which benefits from piezoelectric stack actuator as elements of its 18 active struts has high strength and shows excellent robustness and effectiveness in vibration suppression of launch vehicle on satellite.

Analysis of Tribological Performance of Piston Ring Lubrication

2011 ◽  
Author(s):  
Yibin Guo ◽  
Wanyou Li ◽  
Dequan Zou ◽  
Xiqun Lu ◽  
Tao He
Keyword(s):  
Film Thickness ◽  
Friction Force ◽  
Power Loss ◽  
Piston Ring ◽  
Design Parameters ◽  
Oil Film ◽  
Starved Lubrication ◽  
Piston Ring Lubrication ◽  
Cylinder Bore ◽  
Lubrication Conditions

In this paper a mixed lubrication model considering lubricant supply conditions on cylinder bore has been developed for the piston ring lubrication. The numerical procedures of both fully flooded and starved lubrication were included in the model. The lubrication equations and boundary conditions at the end of strokes were discussed in detail. The effects of piston ring design parameters, such as ring face profile and ring tension, on oil film thickness, friction force and power loss under fully flooded and starved lubrication conditions due to available lubricant supply on cylinder bore were studied. The simulation results show that the oil available in the inlet region of the oil film is important to the piston ring friction power loss. With different ring face crown heights and tensions, the changes of oil film thickness and friction force were apparent under fully flooded lubrication, but almost no changes were found under starved lubrication except at the end of a stroke. In addition, the oil film thickness and friction force were affected evidently by the ring face profile offsets under both fully flooded and starved lubrication conditions, and the offset towards the combustion chamber made a large contribution to forming thicker oil film during the expansion stroke. So under different lubricant supply conditions on the cylinder bore, the ring profile and tension need to be adjusted to reduce the friction and power loss. Moreover, the effects of lubricant viscosity, surface composite roughness, and engine operating speed on friction force and power loss were also discussed.

The Benefits of a Modified-Chemistry, High-Strength, Low-Alloy Steel

1987 ◽  
Vol 3 (02) ◽  
pp. 111-118
Author(s):  
John C. West
Keyword(s):  
Heat Input ◽  
Arc Welding ◽  
High Strength ◽  
Submerged Arc Welding ◽  
Low Alloy Steel ◽  
Labor Costs ◽  
Lower Strength ◽  
The Cost ◽  
High Degree ◽  
Submerged Arc

Steels with 50 ksi and up yield points usually acquire their strength from some form of heat treatment. Most of these steels, 11/2 in. thick and up, must be welded using sustained preheat and controlled interpass temperatures, plus controlled welding heat input of approximately 50 to 60 kJ/in. These two items can add as much as 50 percent to the cost of submerged-arc welding, and increases of up to 30 percent are common for manual welding when compared with lower-strength steels previously used. To reduce costs, a quenched and precipitation-hardened steel, ASTM A710 Grade A Class 3, with a high degree of weldability, was tested. This steel, which can be welded without sustained preheat and almost unlimited heat input, has been extensively tested in thicknesses from 21/4 through 6 in. Although this steel costs more than the usual quenched-and-tempered plates at these strength levels, reductions of 40 to 75 percent in welding labor costs are probable. In addition, sizeable material savings should be realized when these items are used in place of HY-80 and HY-100.

Microstructure, mechanical properties and tribological behavior of a novel low-alloy high strength Mg–2Zn-0.5Zr-0.5Nd alloy

Vacuum ◽  
2020 ◽  
Vol 179 ◽  
pp. 109518 ◽  
Author(s):  
Changhong Cai ◽  
Renbo Song ◽  
Shiguang Peng ◽  
Yongjin Wang ◽  
Jingyuan Li
Keyword(s):  
Mechanical Properties ◽  
Tribological Behavior ◽  
High Strength

scholarly journals Optimum Choice of Energy System Configuration and Storages for a Proper Match between Energy Conversion and Demands

Energies ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3957
Author(s):  
Andrea Lazzaretto ◽  
Andrea Toffolo
Keyword(s):  
Energy Conversion ◽  
Energy System ◽  
Distribution Networks ◽  
Design Parameters ◽  
System Configuration ◽  
Or Groups ◽  
Energy Conversion And Storage ◽  
Proper Design ◽  
And Storage ◽  
Distribution Grids

This Special Issue addresses the general problem of a proper match between the demands of energy users and the units for energy conversion and storage, by means of proper design and operation of the overall energy system configuration. The focus is either on systems including single plants or groups of plants, connected or not to one or more energy distribution networks. In both cases, the optimum design and operation involve decisions about thermodynamic processes, about the type, number, design parameters of components/plants, and storage capacities, and about mutual interconnections and the interconnections with the distribution grids. The problem is very wide, can be tackled with different methodologies and may have several, more or less valuable and complicated solutions. The twelve accepted papers certainly represent a good contribution to perceive its difficulty.

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