scholarly journals Numerical evaluation of expansion loops for pipe subjected to thermal displacements

2021 ◽  
Vol 9 (1) ◽  
pp. 72-80
Author(s):  
Hartono Yudo ◽  
Sarjito Jokosisworo ◽  
Wilma Amiruddin ◽  
Pujianto Pujianto ◽  
Tuswan Tuswan ◽  
...  
Keyword(s):  
Safety Factor ◽  
Numerical Evaluation ◽  
High Stress ◽  
Temperature Expansion ◽  
Finite Element Software ◽  
Working Temperature ◽  
A Value ◽  
Allowable Stresses ◽  
Diameter Pipe ◽  
Thermal Displacements

Abstract The thermal expansion can lead to the high stress on the pipe. The problem can be overcome using expansion loops in a certain length depending on the material’s elastic modulus, diameter, the amount of expansion, and the pipe’s allowable stresses. Currently, there is no exact definition for the dimension of expansion loops design both for loop width (W) and loop footing height (H) sizes. In this study, expansion loops were investigated with using ratio of width and height (W/H) variations to understand pipe stress occurring on the expansion loops and the expansion loops’ safety factor. Relationship between non dimensional stress on the expansion loop pipe was studied numerically by finite element software on several working temperatures of 400oF, 500oF, 600oF, and 700oF. It can be found that stress occurring on the pipes increases as the increases of W/H of the expansion loops and results in a lower safety factor. The safety factor of the expansion loops pipe has a value of 1 when the ratio of loop width and loop footing height (W/H) value was 1.2 for a 16-inch diameter pipe. Stress occurring on the pipe increases with the increase of the working temperature. Expansion loops pipe designed for 400oF can still work well to handle thermal extension pipe occurring on 500oF.

scholarly journals Stability Analysis of Ecological Slopes Based on a 3D Finite Element Model

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
ZiFan Sui ◽  
Weijia Yuan ◽  
Wen Yi ◽  
Weihuan Yang
Keyword(s):  
Finite Element ◽  
Root System ◽  
Safety Factor ◽  
Cynodon Dactylon ◽  
Plant Protection ◽  
Lateral Roots ◽  
Plant Distribution ◽  
Plant Roots ◽  
Research Subjects ◽  
Finite Element Software

To explore the effect of grass and shrub plant roots on the stability of soil slopes in rainy areas in the south, this article relies on the Longlang Expressway construction project. Cynodon dactylon and Magnolia multiflora were selected as research subjects. The plant distribution characteristics and mechanical properties are analyzed. This paper uses ABAQUS finite element software to construct a 3D model of the planted slope in the test section. The stress and strain on the root system and the soil were observed, and the variation law of slope stability before and after plant protection under different rainfall events was compared and analyzed. The test and simulation results show that the root content of Cynodon dactylon gradually decreases with increasing depth. Cynodon dactylon was mainly distributed in the 0–30 cm soil body, and its effect on improving the cohesion of the soil body reached 75%. Magnolia multiflora belongs to vertical roots and has a strong and longer main root with relatively developed lateral roots. Its root system passes through the sliding surface of the slope bottom, which reduces the maximum equivalent plastic stress generated inside the slope by 61%. When the total rainfall duration is unchanged, under the three rainfall intensities of small, medium, and large, herbaceous plants increase the safety factor of the soil by 1.33%, 2.08%, and 6.1%, respectively, and the roots of shrubs increase the safety factor of the soil by 3.29%, 4.08%, and 4.32%, respectively. When the rainfall intensity does not change, as the rainfall time increases, the effect of plants on the slope safety factor first gradually increases and eventually stabilizes. The research results provide a reliable theoretical basis for analyzing the effect of plant roots on soil consolidation and slope protection, and they also lay a technical foundation for the promotion and application of ecological slope protection technology.

Safety Factor in Fatigue Under Fluctuating Stresses

1987 ◽  
Vol 109 (4) ◽  
pp. 397-401 ◽  
Author(s):  
V. A. Avakov
Keyword(s):  
Safety Factor ◽  
High Cycle Fatigue ◽  
Stress Amplitude ◽  
Static Strength ◽  
Mean Stress ◽  
Cycle Fatigue ◽  
Safety Factors ◽  
Generalize Expression ◽  
Allowable Stresses ◽  
Number Of Cycles

It is common to assume identical allowable safety factors in static strength [m], defined by mean stress (Sm), and in fatigue [a], defined by stress amplitude (Sa), in order to find the full safety factor (F) under asymmetrical cycles, or to plot any type of the Sm–Sa diagram of allowable stresses. Here additional modification is considered to generalize expression of the full factor of safety in fatigue under asymmetrical stresses, utilizing unequal allowable safety factors in static strength (by mean stress) and in fatigue (by stress amplitude): ([a] ≠ [m]). We assume that loading is stationary, and cumulated number of cycles is large enough to consider high cycle fatigue.

Action potential propagation in inhomogeneous cardiac tissue: safety factor considerations and ionic mechanism

2000 ◽  
Vol 278 (4) ◽  
pp. H1019-H1029 ◽  
Author(s):  
Yan Wang ◽  
Yoram Rudy
Keyword(s):  
Safety Factor ◽  
Cardiac Tissue ◽  
Sodium Current ◽  
Quantitative Measure ◽  
Tissue Expansion ◽  
Membrane Excitability ◽  
Detailed Model ◽  
A Value ◽  
Unidirectional Block ◽  
Tissue Safety

Heterogeneity of myocardial structure and membrane excitability is accentuated by pathology and remodeling. In this study, a detailed model of the ventricular myocyte in a multicellular fiber was used to compute a location-dependent quantitative measure of conduction (safety factor, SF) and to determine the kinetics and contribution of sodium current ( I Na) and L-type calcium current [ I Ca(L)] during conduction. We obtained the following results. 1) SF decreases sharply for propagation into regions of increased electrical load (tissue expansion, increased gap junction coupling, reduced excitability, hyperkalemia); it can be <1 locally (a value indicating conduction failure) and can recover beyond the transition region to resume propagation. 2) SF and propagation across inhomogeneities involve major contribution from I Ca(L). 3) Modulating I Na or I Ca(L) (by blocking agents or calcium overload) can cause unidirectional block in the inhomogeneous region. 4) Structural inhomogeneity causes local augmentation of I Ca(L) and suppression of I Na in a feedback fashion. 5) Propagation across regions of suppressed I Na is achieved via a I Ca(L)-dependent mechanism. 6) Reduced intercellular coupling can effectively compensate for reduced SF caused by tissue expansion but not by reduced membrane excitability.

scholarly journals Stress Heterogeneity and Slip Weakening of Faults under Various Stress and Slip

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-12 ◽  
Author(s):  
Longjun Dong ◽  
Qiaomu Luo
Keyword(s):  
Slip Surface ◽  
Water Pressure ◽  
High Stress ◽  
Local Stress ◽  
Seismic Source ◽  
High Water ◽  
Fault Slip ◽  
Underground Engineering ◽  
Finite Element Software ◽  
Stress Heterogeneity

The rock mass of deep underground engineering is in the complex geological environment of high stress, high temperature, and high water pressure. In the process of deep mining and underground space development, the fault-slip seismic source may cause engineering accidents with strong destructive capacity. An in-depth study of fault slip characteristics is very important in the engineering disaster prevention and control. In this paper, a slip model was established based on the finite element software ABAQUS. A total of 20 loading ways are set for various stress and slip, which include the possible slip conditions of fast slip, slow slip, and critical state. By comparing the simulation diagrams and collecting the data of representative grid elements on the loading surface and slip surface, the slip characteristics such as stress heterogeneity under different loads are analyzed. The results show that the increase of slip velocity will make the slip unstable, and the local stress and deformation will become irregular. The spatial stress heterogeneity and the resulting local high working rate will lead to the decrease of the friction strength and the slip weakening. These results can provide some useful suggestions for the research of seismic activities caused by fault slip.

Strength Analysis of Roller-Metallic Membrane Coupling

2012 ◽  
Vol 268-270 ◽  
pp. 1225-1230
Author(s):  
Liang Shen Wang ◽  
Hong Tu Sun ◽  
Pin Wang ◽  
Jie Hou ◽  
Zai Yu Xie
Keyword(s):  
Safety Factor ◽  
High Stress ◽  
Strength Analysis ◽  
Fatigue Stress ◽  
Bolt Holes ◽  
Common Coupling ◽  
Metallic Membrane

In order to solve the problems of common metallic membrane coupling which is easily damaged a large misalignment compensation coupling is designed. The coupling joins roller coupling with membrane coupling reasonably to ensure the coupling working well in large misalignment condition. Fatigue stress for common coupling and roller-metallic membrane coupling are analyzed by CosmosWorks software. The results show that the zone around bolt holes is easily damaged due to the high stress and lower safety factor. The design of roller-metallic membrane coupling reduces the high stress and lower safety factor zone to increase the anti-fatigue capability of the coupling.

Use of Stress-Strength Model in Determination of Safety Factor for Pressure Vessel Design

1996 ◽  
Vol 118 (1) ◽  
pp. 27-32 ◽  
Author(s):  
S. Quin ◽  
G. E. O. Widera
Keyword(s):  
Safety Factor ◽  
Pressure Vessel ◽  
External Pressure ◽  
Strength Model ◽  
Design Practice ◽  
Factors Affecting ◽  
Normal Distributions ◽  
Combined Loads ◽  
A Value

In pressure vessel design, the values of safety factor are still determined on the basis of engineering experience. Thus, they cannot properly reflect the influence of the consequences of failure and the variabilities in stress and strength. As a result, designsare often excessively conservative, while on the other hand, the possibility of failure still exists. Two approaches for determining the value of the safety factor, which are based on reliability analysis, are presented in this paper. As a result of a comparison, one approach based on a stress-strength model is found to be appropriate for pressure vessel design practice. By transforming the interference parts of the distributions of stress and strength into equivalent normal distributions, the approach allows stress and strength to have arbitrary distributions. Three examples, one in which a vessel is subjected to internal pressure, one in which a tall vessel is subjected to combined loads, and one in which a vessel is subjected to external pressure, are given in the paper. From threexamples, the principles for determining target reliability and the factors affecting the safety factor are discussed. It is concluded that by using the approach presented in this paper for pressure vessel design, different consequences of failure as well as variabilities in stress and strength can be taken into account. The approach yields a value for the safety factor that leads to a design which will be safer and yet more economical.

scholarly journals STUDI PERANCANGAN PISAU PADA MESIN PENCACAH PLASTIK MENGGUNAKAN FINITE ELEMENT ANALYSIS

2021 ◽  
Vol 7 (1) ◽  
pp. 44
Author(s):  
Rizqi Ilmal Yaqin ◽  
Mega Lazuardi Umar ◽  
Sigiet Haryo Pranoto ◽  
Angger Bagus Prasetiyo ◽  
Bambang Hari Priyambodo
Keyword(s):  
Finite Element Analysis ◽  
Safety Factor ◽  
Model Simulation ◽  
Plastic Waste ◽  
Waste Processing ◽  
Safety Factors ◽  
Stress Strain ◽  
Element Analysis ◽  
A Value ◽  
Deformation Parameters

The amount of plastic waste each year will increase by 10% every year which is a problem for a country. Therefore, proper processing of plastic waste needs to be done. Before being processed into plastic waste processing, it is necessary to have a chopping process using a plastic chopping machine. The plastic chopping machine has an important component, namely the chopping knife. Before carrying out the knife manufacturing process, it is necessary to validate the design of the blade that is used with its loading. Model simulation using software is one way to quickly validate the model. This study aims to determine the effect of loading variations on stress, strain, deformation and safety factors of the model. The use of ANSYS R17.2 software is used to analyze the chopping machine knife model with a variation of 5kg / hour, 10kg / hour, 20kg / hour and 50kg / hour capacities. The result is that the stress, strain and deformation parameters have an increase in value with increasing loading variations. The greatest values of stress, strain and deformation are in the variation of 50kg / hour respectively 64.995 Pa; 336.76 and 56,358 x 10-11mm. The value of the safety factor for all variations of loading has a value of 15. The value of the safety factor means that the design of the plastic chopping knife is safe to use up to a loading of 50kg / hour

scholarly journals Design Of Portable Injection Waste Destruction Machine With Sterilization System

2021 ◽  
Vol 2 (5) ◽  
pp. 1800-1807
Author(s):  
Sandy Suryady ◽  
Eko Aprianto Nugroho ◽  
Abdul Muchlis
Keyword(s):  
Safety Factor ◽  
Theoretical Calculations ◽  
Community Health Center ◽  
Frame Structure ◽  
Injection Equipment ◽  
A Value ◽  
Upper Limit ◽  
Plastic Syringe ◽  
Lower Frame ◽  
Waste Destruction

The Community Health Center (Puskesmas) does not yet have special facilities for treating medical waste such as hospitals. Hospital/Puskesmas waste and waste generated by hospital activities and other supporting activities. Make a machine that destroys waste injection equipment equipped with a knife made of SKD as a plastic syringe destroyer. Design of a syringe crushing machine in the form of needles and syringes, Analyze the von misses stress received by the frame structure of the syringe crusher, Analyze the displacement by the load received by the frame structure of the syringe crusher, Analyze the safety factor of the frame structure of the crusher syringe. Analyzing using solidworks 2016 software, the results obtained are the maximum value of von misses, displacement, and safety of factor from the lower frame of the syringe waste crusher machine. Von misses stress obtained in the analysis using Solidworks 2016 gets a value of 48.54 Mpa in software calculations, while in theoretical calculations it is 48.01 Mpa. The percentage of errors calculated by software and theory is 1%. The displacement obtained in the analysis using Solidworks 2016 software is 0.34 mm in theoretical calculations of 0.35 mm. The percentage of errors calculated by software and theory is 2%. The safety factor obtained in the solidwork analysis gets a value of 4.7 ul (upper limit), while the theoretical calculation is 5.2 ul (upper limit) which means this frame is declared safe when the engine is operating.

scholarly journals THE ANALYSIS OF SEISMOTECTONICS, PERIODICITY, AND CHANGING OF QUAKES LEVEL IN WEST NUSA TENGGARA AREA BASED ON 1973 – 2015 DATA

2019 ◽  
Vol 2 (1) ◽  
pp. 37
Author(s):  
Melinda Utami Istiqomah ◽  
Bambang Sunardi ◽  
Marzuki Marzuki ◽  
Suhayat Minardi
Keyword(s):  
High Stress ◽  
The United States ◽  
B Value ◽  
Disaster Mitigation ◽  
Likelihood Method ◽  
United States Geological Survey ◽  
Seismicity Rate ◽  
A Value ◽  
Value Range ◽  
Seismicity Rate Changes

This research was conducted as one of the earthquake disaster mitigation efforts in Nusa Tenggara Barat region, because this region is one of the regions in Indonesia which has a relatively high level of seismicity. The purpose of this research is to determine seismotectonic parameter, earthquake periodicity along with the average of seismicity rate changes in Nusa Tenggara Barat region. The data used in this research is the data sourced from the United States Geological Survey (USGS) and Badan Meteorologi Klimatologi dan Geofisika (BMKG) from Januari 1973 until February 2015 for Bali Strait region up to Banda Sea with coordinate boundaries of 1140–1300 East Longitude and 40-130 South Latitude. This research was conducted using the maximum likelihood method with second party of software Zmap ver 6.0 also software ArcGis ver 10 to map seismotectonic parameter, periodicity and the average velocity of seismicity rate changes. Variation b value range between 0.972–1.44, a low value of b are associated with high stress levels, and vice versa. The a value range between 6.67- 9.1, its show that the regions with high a value experience a relatively high earthquake incidence rate, and vice versa. The density of earthquake is about -2.63 to -2.01 logN/km2 or the occurrence of earthquakes in the area is very rare. Earthquake periodicity with magnitude (M) 6 SR is 5 to 18 year, M 6.5 SR is 16 to 67 year, M 7 SR is 54 to 304 year, and M 7.5 SR is 178 to 1.386 year. The average of seismicity rate changes on a case that occurred in Sumbawa in 1982 is more than 125%, meanwhile the earthquake that occurred in 2009 is more than 75%.Copyright © 2019IPR. All rights reserved.

Study on the Role of Geogrid-Reinforced for Fly Ash Retaining Wall Basing on the Analysis of FLAC3D

2011 ◽  
Vol 368-373 ◽  
pp. 599-603
Author(s):  
Wei Shi ◽  
Jin Han ◽  
Yong Bin Li
Keyword(s):  
Fly Ash ◽  
Safety Factor ◽  
Lateral Displacement ◽  
Retaining Wall ◽  
Vertical Displacement ◽  
Design Parameters ◽  
Finite Element Software ◽  
The Stability ◽  
The Impact

Geogrid-reinforced retaining wall is widely used in civil engineering, the role of geogrid reinforcement and the calculations of reinforcement material in the retaining wall design need further refinement.This paper analyzes the fly ash retaining wall with and without reinforcement by using finite element software of FLAC3D,studys the impact of geogrid-reinforced function on the stability of fly ash retaining wall ,gets the design parameters of geogrid-reinforced fly ash retaining wall.The numerical results show that: the fly ash retaining walls' safety factor is lower when its height is greater than 6m,reinforcement is needed for fly ash retaining wall to improve its safety factor to ensure the stability of retaining wall.Simulate and analyze the 8m high geogrid reinforced fly ash retaining wall,the results show that: increasing the reinforcement spacing can increase the lateral and vertical displacement of geogrid reinforced fly ash retaining wall, the maximum vertical displacement of retaining wall is in the upper wall,maximum lateral displacement occurs in the lower parts of the retaining wall;the reasonable distance of 8m high fly ash retaining wall is 0.8m.

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