scholarly journals Fatigue Resistance Models of Structural for Risk Based Inspection

2020 ◽  
Vol 6 (2) ◽  
pp. 375-383
Author(s):  
Sergei Belodedenko ◽  
V. Hanush ◽  
A. Baglay ◽  
О. Hrechanyі
Keyword(s):  
Fatigue Resistance ◽  
Influence Factors ◽  
High Strength ◽  
Technical Condition ◽  
Damage Function ◽  
Fatigue Tests ◽  
Structural Elements ◽  
Model Combining ◽  
Safety Margins ◽  
Complex Indicators

The current stage of civil engineering is characterized by special attention to the safety of structures with a long service life. Such objects were designed several decades ago and their safe operation was ensured by significant safety margins. Now this approach to safety has been replaced by the concept of acceptable risk. It forms the basis of a risk based inspection (RBI) maintenance strategy. The transition from preventive maintenance strategies to a technical condition maintenance is substantiated. Complex indicators of technical condition, suitable for RBI- maintenance, are considered. The methodology of the resource safety index (RSI) is proposed. The latter is used as an indicator of risk. Special models of fatigue resistance is required for its control. The purpose of this paper is to build fatigue models for critical structural elements that are serviced according to the RBI concept. Instead of the traditional S-N curve, the lifetime general equation (first model) be used, where by the arguments are the main influence factors. Along with this, a modified ε - N equation is proposed for deformation criteria. The novelty of this equation is that it uses the rate of S-N- curve (slope) obtained in the first model with high cycle fatigue. The second model, combining the results of fatigue tests, is the equation for the dispersion of durability. The third model is the accumulated damage function under overloads. The efficiency of the RSI method is demonstrated by the example of the reliability assessment of the high strength bolts. Thanks to RSI method forecasting, during RBI-maintenance, parts can be used 3-5 times longer than with traditional methods.

scholarly journals ЭКСПЕРИМЕНТАЛЬНОЕ ОПРЕДЕЛЕНИЕ ОСТАТОЧНОЙ ПРОЧНОСТИ ЭЛЕМЕНТОВ КОНСТРУКЦИЙ ПАРАШЮТОВ, ИСЧЕРПАВШИХ ЗАДАННЫЙ СРОК ЭКСПЛУАТАЦИИ

2019 ◽  
pp. 80-87
Author(s):  
Кирило Вікторович Миронов ◽  
Євген Федорович Кучерявий
Keyword(s):  
Compressive Force ◽  
High Strength ◽  
Technical Condition ◽  
Suspension System ◽  
Structural Elements ◽  
Design Elements ◽  
Textile Materials ◽  
Wide Range ◽  
Speed Up ◽  
Working Section

To make a decision on determining the periods of safe operation of parachute systems that have exhausted a given resource, it is necessary to know the parameters of their actual technical condition. Experimental destructive methods for determining the parameters of residual strength are considered: breaking strength and relative deformations during the breaking of the standard specimens.Parachute design elements to be examined include parachute dome fabrics, carcass reinforcement ribbons, strops, and suspension system belts. In order to ensure that all requirements set forth by regulatory documents for conducting an experiment with textiles, specialized devices have been developed, designed, manufactured and tested experimentally. These devices provide strength experiments on a universal tensile machine designed to work with samples of metallic materials.The need to create specialized devices is caused by a very wide range of braking forces (from tens to several thousand newtons), as well as by the specifics of synthetic textile materials of the parachute design elements. A set of devices has been developed that provide the required conditions for conducting rupture experiments on samples of textile materials. The created devices provide sufficient compressive force of the sample in the clips without slip-page and without violating the integrity of the contact surface of the studied synthetic textile materials. Ensuring that the sample is sufficiently compressed in the clamping devices of the tearing machine is ensured by special transitional gaskets and methods for creating a compressing force on the sample. Compressing devices and devices for conducting experiments with low-strength specimens of the dome fabric, with medium-strong reinforcing skeleton tapes, strops and high-strength straps of the suspension system are created. In order to speed up the preparation of samples for the experiment, methodologies have been created that ensure the required length of the working part of the sample and its fixation without warps. A universal strain gauge was developed to determine the change in the length of the working section of the specimen in 100 mm. Installing the meter on the sample under study allows you to measure displacements up to rupture. The meter is fastened to the specimen using spring clips. The developed devices were tested during the experiment with hundreds of samples of the structural elements of 3 parachutes.

Welding Properties and Fatigue Resistance of S690QL High Strength Steels

2015 ◽  
Vol 812 ◽  
pp. 29-34 ◽  
Author(s):  
Ádám Dobosy ◽  
János Lukács
Keyword(s):  
Fatigue Resistance ◽  
Welded Joints ◽  
Gas Metal Arc Welding ◽  
Research Work ◽  
Base Material ◽  
High Strength Steels ◽  
High Strength ◽  
Fatigue Tests ◽  
Metal Arc Welding ◽  
Welding Properties

The objective of this article is to present the first results of our research work. In order to determination and comparison of the fatigue resistance, high cycle fatigue tests (HCF) were performed on RUUKKI OPTIM S690QL quenched and tempered high strength steel. In parallel these; welded joints were made on the same steel using gas metal arc welding (GMAW, MIG/MAG) to preparation of the cyclic investigations of the welded joints. In the article, the performance of the welding experiments will be presented; along with the results of the HCF tests executed on the base material and its welded joints. Furthermore, our results will be compared with different literary data.

scholarly journals Multi-Stage Cold Forging Process for Manufacturing a High-Strength One-Body Input Shaft

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 532
Author(s):  
A Jo ◽  
Myeong Jeong ◽  
Sang Lee ◽  
Young Moon ◽  
Sun Hwang
Keyword(s):  
High Strength ◽  
Microstructural Characterization ◽  
Fatigue Tests ◽  
Machining Process ◽  
Cold Forging ◽  
Element Analysis ◽  
Forging Process ◽  
Input Shaft ◽  
Multi Stage ◽  
The One

A multi-stage cold forging process was developed and complemented with finite element analysis (FEA) to manufacture a high-strength one-body input shaft with a long length body and no separate parts. FEA showed that the one-body input shaft was manufactured without any defects or fractures. Experiments, such as tensile, hardness, torsion, and fatigue tests, and microstructural characterization, were performed to compare the properties of the input shaft produced by the proposed method with those produced using the machining process. The ultimate tensile strength showed a 50% increase and the torque showed a 100 Nm increase, confirming that the input shaft manufactured using the proposed process is superior to that processed using the machining process. Thus, this study provides a proof-of-concept for the design and development of a multi-stage cold forging process to manufacture a one-body input shaft with improved mechanical properties and material recovery rate.

C80 Early Strength Micro Expansion of Steel Tube Reinforced Concrete Research

2015 ◽  
Vol 1119 ◽  
pp. 752-755
Author(s):  
Chang Zheng Sun ◽  
Zheng Wang
Keyword(s):  
High Performance ◽  
Raw Materials ◽  
Influence Factors ◽  
High Strength ◽  
Steel Tube ◽  
Strength Analysis ◽  
Self Compacting Concrete ◽  
Mix Proportion ◽  
Early Strength ◽  
Working Performance

Optimization of mix proportion parameter ，Using ordinary raw materials makes a C80 high performance self-compacting concrete;By joining a homemade perceptual expansion agent, significantly improve the early strength of concrete and effective to solve the high strength of self-compacting concrete caused by gelled material consumption big contraction;Further study on the working performance of high-strength self-compacting concrete, age strength, analysis the influence factors of concrete are discussed.

Fatigue and Burst Analysis of Hy-140(T) Steel Pressure Vessels

1970 ◽  
Vol 92 (1) ◽  
pp. 11-16 ◽  
Author(s):  
J. M. Barsom ◽  
S. T. Rolfe
Keyword(s):  
Yield Strength ◽  
Pressure Vessel ◽  
Low Cycle Fatigue ◽  
High Strength Steels ◽  
High Strength ◽  
Fatigue Tests ◽  
Pressure Vessels ◽  
High Yield ◽  
Corrosion Properties ◽  
Burst Analysis

Increasing use of high-strength steels in pressure-vessel design has resulted from emphasis on decreasing the weight of pressure vessels for certain applications. To demonstrate the suitability of a 140-ksi yield strength steel for use in unwelded pressure vessels, HY-140(T)—a quenched and tempered 5Ni-Cr-Mo-V steel—was fabricated and subjected to various burst and fatigue tests, as well as to various laboratory tests. In general, results of the investigation indicated very good tensile, Charpy, Nil Ductility Transition Temperature (NDT), low-cycle fatigue, and stress-corrosion properties of HY-140(T) steels, as well as very good burst tests results, in comparison with existing high-yield strength pressure-vessel steels. The results also indicate that the HY-140(T) steel should be an excellent material for its originally designed purpose, Naval hull applications.

Effect of Plasma Cutting on the Fatigue Resistance of Fe510 D1 Steel

1999 ◽  
Vol 122 (1) ◽  
pp. 141-145 ◽  
Author(s):  
M. Chiarelli ◽  
A. Lanciotti ◽  
M. Sacchi
Keyword(s):  
Fatigue Resistance ◽  
Low Carbon Steel ◽  
Physical And Mechanical Properties ◽  
Research Programme ◽  
Fatigue Tests ◽  
Automatic Process ◽  
Plasma Cutting ◽  
Low Carbon ◽  
The University

The paper describes the results of a research programme, carried out at the Department of Aerospace Engineering of the University of Pisa, for the assessment of the influence of plasma cutting on the physical and mechanical properties of Fe510 D1, a low carbon steel widely used in carpentry. The activity started by observing that several industries rework plasma cut edges, particularly in the case of fatigue structures, in spite of the good quality of the plasma cut edges in a fully automatic process. Obviously, reworking is very expensive and time-consuming. Comparative fatigue tests demonstrated that the fatigue resistance of plasma cut specimens in Fe510 steel was fully comparable to that of milled specimens, as the consequence of the beneficial residual stresses which formed in the plasma cut edges. [S0094-4289(00)02201-5]

The Study on the Ratio of Similar Material in Landslide Model Test

2011 ◽  
Vol 261-263 ◽  
pp. 1679-1684
Author(s):  
Xiao Ling Liu ◽  
Shi Mei Wang ◽  
Yun Zhi Tan ◽  
Xin Jiang Hu ◽  
Dai Peng Zhao
Keyword(s):  
Model Test ◽  
Influence Factors ◽  
Deformation Modulus ◽  
High Strength ◽  
Similar Material ◽  
Talcum Powder ◽  
Angle Of Internal Friction ◽  
Similar Materials ◽  
Mixed Material ◽  
Landslide Model

The choice of similar materials and the design of mix proportions is a key step in landslide model test. On the basis of experiment, we conduct a research for the similar materials which may sufficing volume weight, cohesive force, angle of internal friction, deformation modulus, and the infiltration coefficient on the same time. Then we put forward two kinds of schemes: one is the mixed material of high-strength glass micro beads and talcum powder; the other is the mixed material of lead beads, river sands, rubber powder and talcum powder. By analyzing the result of mix proportions test, We concluded the regularity that similar index varies along with different content of the similar material ingredients and found the notable influence factors , which provides important reference for the components of similar materials in the landslide model test.

scholarly journals Multiaxial fatigue study on steel transversal attachments under constant amplitude proportional and non-proportional loadings

2018 ◽  
Vol 165 ◽  
pp. 16007
Author(s):  
Martin Garcia ◽  
Claudio A. Pereira Baptista ◽  
Alain Nussbaumer
Keyword(s):  
Fatigue Life ◽  
High Strength ◽  
Fatigue Tests ◽  
Multiaxial Fatigue ◽  
Life Assessment ◽  
Experimental Program ◽  
Proportional Loading ◽  
Load Carrying ◽  
Stress States ◽  
Experimental Values

In this study, the multiaxial fatigue strength of full-scale transversal attachment is assessed and compared to original experimental results and others found in the literature. Mild strength S235JR steel is used and an exploratory investigation on the use of high strength S690QL steel and the effect of non-proportional loading is presented. The study focuses on non-load carrying fillet welds as commonly used in bridge design and more generally between main girders and struts. The experimental program includes 33 uniaxial and multiaxial fatigue tests and was partially carried out on a new multiaxial setup that allows proportional and non-proportional tests in a typical welded detail. The fatigue life is then compared with estimations obtained from local approaches with the help of 3D finite element models. The multiaxial fatigue life assessment with some of the well-known local approaches is shown to be suited to the analysis under multiaxial stress states. The accuracy of each models and approaches is compared to the experimental values considering all the previously cited parameters.

scholarly journals Changing in Fatigue Life of 300 M Bainitic Steel After Laser Carburizing and Plasma Nitriding

2018 ◽  
Vol 165 ◽  
pp. 21002 ◽  
Author(s):  
Antonio J. Abdalla ◽  
Douglas Santos ◽  
Getúlio Vasconcelos ◽  
Vladimir H. Baggio-Scheid ◽  
Deivid F. Silva
Keyword(s):  
Mechanical Properties ◽  
Fatigue Life ◽  
Plasma Nitriding ◽  
Fatigue Behavior ◽  
High Strength ◽  
Tensile Tests ◽  
Steel Sample ◽  
Fatigue Tests ◽  
300M Steel ◽  
Structural Applications

In this work 300M steel samples is used. This high-strength steel is used in aeronautic and aerospace industry and other structural applications. Initially the 300 M steel sample was submitted to a heat treatment to obtain a bainític structure. It was heated at 850 °C for 30 minutes and after that, cooled at 300 °C for 60 minutes. Afterwards two types of surface treatments have been employed: (a) using low-power laser CO2 (125 W) for introducing carbon into the surface and (b) plasma nitriding at a temperature of 500° C for 3 hours. After surface treatment, the metallographic preparation was carried out and the observations with optical and electronic microscopy have been made. The analysis of the coating showed an increase in the hardness of layer formed on the surface, mainly, among the nitriding layers. The mechanical properties were analyzed using tensile and fatigue tests. The results showed that the mechanical properties in tensile tests were strongly affected by the bainitic microstructure. The steel that received the nitriding surface by plasma treatment showed better fatigue behavior. The results are very promising because the layer formed on steel surface, in addition to improving the fatigue life, still improves protection against corrosion and wear.

High Cycle Fatigue Resistance and Reliability Assessment of Flexible Printed Circuitry

2002 ◽  
Vol 124 (3) ◽  
pp. 254-259 ◽  
Author(s):  
Elena Martynenko ◽  
Wen Zhou ◽  
Alexander Chudnovsky ◽  
Ron S. Li ◽  
Larry Poglitsch
Keyword(s):  
Fatigue Resistance ◽  
High Cycle Fatigue ◽  
Failure Mechanisms ◽  
Three Dimensional ◽  
Reliability Assessment ◽  
Core Layer ◽  
High Strength ◽  
Multiple Cracks ◽  
Material System ◽  
Cycle Fatigue

Flexible printed circuitry (FPC) is a patterned array of conductors supported by a flexible dielectric film made of high strength polymer material such as polyimide. The flexibility of FPC provides an opportunity for three dimensional packaging, easy interconnections and dynamic applications. The polymeric core layer is the primary load bearing structure when the substrate is not supported by a rigid plate. In its composite structure, the conductive layers are more vulnerable to failure due to their lower flexibility compared to the core layer. Fatigue data on FPCs are not commonly available in published literature. Presented in this paper is the fatigue resistance and reliability assessment of polyimide based FPCs. Fatigue resistance of a specific material system was analyzed as a function of temperature and frequency through experiments that utilized a specially designed experimental setup consisting of sine servo controller, electrodynamic shaker, continuity monitor and temperature chamber. The fatigue characteristics of the selected material system are summarized in the form of S-N diagrams. Significant decrease in fatigue lifetime has been observed due to higher displacements in high cycle fatigue. Observed temperature effect was however counter-intuitive. Failure mechanisms are discussed and complete fracture analysis is presented. In various FPC systems, it has been found that the changes take place in FPC failure mechanisms from well-developed and aligned single cracks through the width at low temperature to an array of multiple cracks with random sizes and locations at high temperature.

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