scholarly journals The Influence Factors of Grain Integrity under the Internal Pressure Condition in SRM

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Chunguang Wang ◽  
Weiping Tian
Keyword(s):  
Internal Pressure ◽  
Influence Factors ◽  
External Pressure ◽  
Thick Wall ◽  
Stress And Strain ◽  
Three Dimension ◽  
Pressure Condition ◽  
Working Process ◽  
Hoop Strain ◽  
Inner Surface

To investigate the influence factors of propellant grain integrity under the internal pressure, the cylindrical grain was equivalent to a thick-wall cylinder and its three-dimension stress-strain problem was solved. Under the internal and external pressure, the strain and displacement equations of the inside thick-wall cylinder were expressed, and then, the stress and strain expressions of grain were obtained. On this basis, the hoop strain equations on the inside surface of the cylindrical grain and case were developed. The hoop strain on the inner surface of the grain can be predicted by the hoop strain of the case cylinder via the strain equations, and therefore, the hoop strain in the inner surface can be indirectly monitored in real time during the working process of the motor. The hoop strain in the inner surface of grain can be effectively reduced by increasing the case stiffness or decreasing the m number of the grain.

STUDY OF STRESS AND STRAIN RATES IN A ROTATING CYLINDER SUBJECTED TO INTERNAL AND EXTERNAL PRESSURE

2012 ◽  
Vol 01 (02) ◽  
pp. 1250022 ◽  
Author(s):  
NEERAJ CHAMOLI ◽  
MINTO RATTAN ◽  
SATYA BIR SINGH
Keyword(s):  
Internal Pressure ◽  
Strain Rate ◽  
Creep Behavior ◽  
Particulate Composite ◽  
External Pressure ◽  
Stress And Strain ◽  
Strain Rates ◽  
Tresca Criterion ◽  
Stress And Strain Rate ◽  
Silicon Carbide Particulate

The creep behavior of a thick walled hollow circular cylinder, made of aluminum silicon carbide particulate composite material has been investigated in the present study and creep behavior in this case is assumed to follow Sherby's constitutive model. The stress and strain rate distributions of cylinder rotating about its own axis, have been obtained using von Mises and Tresca yield criteria. The effect of pressure on the stresses and strain rates in the cylinder has been investigated and it is observed that with the increase of the internal pressure in the cylinder the strain rate increases. The introduction of external pressure along with the internal pressure causes the strain rates to decrease. It is also observed that the values of effective stress and strain rate obtained using Tresca criterion are higher than those obtained using Mises criterion. Thus it is suggested to use Tresca criterion for the analysis while designing the cylinder.

Fitness for Service Assessments of Bulging and Out-of-Round Structures

2004 ◽  
Author(s):  
Peter Carter ◽  
D. L. Marriott ◽  
M. J. Swindeman
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Internal Pressure ◽  
Structural Model ◽  
External Pressure ◽  
Element Analysis ◽  
Structural Imperfection ◽  
Level 2

This paper examines techniques for the evaluation of two kinds of structural imperfection, namely bulging subject to internal pressure, and out-of-round imperfections subject to external pressure, with and without creep. Comparisons between comprehensive finite element analysis and API 579 Level 2 techniques are made. It is recommended that structural, as opposed to material, failures such as these should be assessed with a structural model that explicitly represents the defect.

Ratcheting assessment of corroded elbow pipes subjected to internal pressure and cyclic bending moment

2021 ◽  
pp. 030932472198989
Author(s):  
Ali Salehi ◽  
Armin Rahmatfam ◽  
Mohammad Zehsaz
Keyword(s):  
Growth Rate ◽  
Stainless Steel ◽  
Internal Pressure ◽  
Bending Moment ◽  
Axial Direction ◽  
Hoop Strain ◽  
Cyclic Bending ◽  
High Fatigue ◽  
The Impact ◽  
Cyclic Bending Moment

The present study aimed to study ratcheting strains of corroded stainless steel 304LN elbow pipes subjected to internal pressure and cyclic bending moment. To this aim, spherical and cubical shapes corrosion are applied at two depths of 1 mm and 2 mm in the critical points of elbow pipe such as symmetry sites at intrados, extrados, and crown positions. Then, a Duplex 2205 stainless steel elbow pipe is considered as an alternative to studying the impact of the pipe materials, due to its high corrosion resistance and strength, toughness, and most importantly, the high fatigue strength and other mechanical properties than stainless steel 304LN. In order to perform numerical analyzes, the hardening coefficients of the materials were calculated. The results highlight a significant relationship between the destructive effects of corrosion and the depth and shape of corrosion, so that as corrosion increases, the resulting destructive effects increases as well, also, the ratcheting strains in cubic corrosions have a higher growth rate than spherical corrosions. In addition, the growth rate of the ratcheting strains in the hoop direction is much higher across the studied sample than the axial direction. The highest growth rate of hoop strain was observed at crown and the highest growth rate of axial strains occurred at intrados position. Altogether, Duplex 2205 material has a better performance than SS 304LN.

Influence of Inner Surface Defects on the Fatigue Strength of Pipe Subjected to Cyclic Internal Pressure

1978 ◽  
Vol 100 (4) ◽  
pp. 360-368
Author(s):  
Y. Yazaki ◽  
S. Hashirizaki ◽  
S. Nishida ◽  
C. Urashima
Keyword(s):  
Fatigue Strength ◽  
Internal Pressure ◽  
Test Specimen ◽  
Surface Defects ◽  
Fatigue Crack Initiation ◽  
Internal Surface ◽  
Fatigue Tests ◽  
Inner Surface ◽  
Surface Notch ◽  
Medium Diameter

Cyclic internal oil pressure fatigue tests were carried out on medium-diameter ERW pipes of API 5LX - X60 in an attempt to determine the influence of surface defects on the fatigue strength. Experimental factors investigated were the depth and location of internal surface notch in relation to the axis of pipe. The specimen was subjected to cyclic internal pressure, the cyclic rate being 0.3–0.5 Hz. During the test, Acoustic Emission (AE) techniques were applied to detect the fatigue crack initiation. Along with the aforementioned fatigue tests, pulsating tension fatigue tests were carried out on specimens with the same surface notches as the cyclic internal pressure fatigue test specimen.

A Theoretical and Experimental Analysis of the Bending Behavior of Unbonded Flexible Pipes

2014 ◽  
Author(s):  
Tatiana Vargas-Londoño ◽  
José Renato M. de Sousa ◽  
Carlos Magluta ◽  
Ney Roitman
Keyword(s):  
Internal Pressure ◽  
Cross Section ◽  
Structural Response ◽  
Experimental Tests ◽  
Theoretical Models ◽  
External Pressure ◽  
Local Behavior ◽  
Flexible Pipes ◽  
Floating System ◽  
Bending Loads

Due to its compound cross-section, the prediction of the structural response of flexible pipes to loads such as their self-weight, internal and external pressure, movements imposed by the floating system and environmental loads such as currents, waves and wind is quite complex. All these loads generate stresses and strains in the cross section of the pipe that have to be properly evaluated in order to ensure integrity of the line. Research has been done on the local behavior of flexible pipes under combined axisymmetric loads as well as under bending loads. However, there is a lack of research combining both axisymmetric and bending loads, as also in the study of the strains in the tensile amour layers of the pipes, aspects which are important for the calibration of theoretical models to predict such behavior. Based on that, this study aims to evaluate the local behavior of flexible pipes under combinations of axisymmetric (tension, and internal pressure) and bending loads via a series of experimental tests in a 9.13″ I.D pipe. In the experimental tests, the behavior of the pipe was studied for three load combinations: i) bending combined with tension; ii) bending combined with internal pressure; and iii) bending combined with tension and internal pressure. Based on these tests, the authors obtained the strains in the tensile armor layer, axial elongation due to tension, axial reaction forces due to internal pressure, and deflection due to bending. These measurements were used to calibrate a theoretical model devoted to simulate the pipe’s response, getting accurate results for stiffness and stresses of the pipe in each scenario.

A Conceptual Model of Green HRM Adoption Towards Sustainability in Hospitality Industry

2019 ◽  
pp. 400-421 ◽  
Author(s):  
Yusmani Mohd Yusoff ◽  
Mehran Nejati
Keyword(s):  
Human Resource Management ◽  
Internal Pressure ◽  
Financial Performance ◽  
Human Resource ◽  
Hospitality Industry ◽  
External Pressure ◽  
Resource Based View ◽  
Proposed Model ◽  
Level Of Understanding ◽  
Green Human Resource Management

This chapter seeks to provide a better understanding on the predictors of green human resource management which can result in improved environmental and financial performance across hospitality industry. The proposed model has been constructed from the perspective of external pressure (i.e., normative) and internal pressure (manager's environmental concerns) by using the Institutional Theory and Resource Based View Theory. The chapter examines the antecedents of sustainability in hospitality industry in terms of improved financial and environmental performance. It therefore expands the level of understanding on mechanisms which leads to corporation sustainability. While the chapter is written with a focus on hospitality industry, the proposed model is applicable to corporations across other sectors.

On the response and prediction of multi-layered flexible riser under combined load conditions

2019 ◽  
Vol 36 (8) ◽  
pp. 2507-2529 ◽  
Author(s):  
Mengsha Liu ◽  
J.Y. Li ◽  
Lixin Chen ◽  
J.S. Ju
Keyword(s):  
Numerical Simulation ◽  
Internal Pressure ◽  
Internal Force ◽  
External Pressure ◽  
Prediction Methods ◽  
Flexible Riser ◽  
Content Type ◽  
Combined Load ◽  
Simulation Results ◽  
Load Conditions

Purpose The internal force is more complicated in a combined load case than in a single load case, and the influence of the combined load on the stress cannot be neglected. The purpose of this paper is to study the mechanical behavior of the flexible riser under combined load conditions of tension and internal pressure or external pressure. Design/methodology/approach The mechanical behavior of the flexible riser under combined load conditions is studied by numerical simulation with a nine-layer detailed finite element model. The layers of flexible riser are modeled separately, and the interactions between layers have been taken into consideration in numerical simulation. Findings Under tension and internal pressure or external pressure, the pressure armor will bear extra external pressure because of the squeezing actions between layers caused by tension, and the extra external pressure will increase proportionately with the increase of the tension. Under internal pressure and tension, the internal stress for tension armor was nearly unchanged compared to that under unique tension load, whereas under external pressure and tension, the change of internal stress for tension armor was significant. Prediction methods of internal force for pressure armor and tension armor under pressure and tension are given, and the result from the formula agrees well with the simulation results. Originality/value The prediction methods on the internal force of flexible riser proposed in this study are proven accurate, with numerical simulation results, and the prediction methods are convenient for engineering applications.

Rheological Aspects of Multilayered Thick-Wall Polymeric Pipes under the Influence of Internal Pressure

2020 ◽  
Vol 869 ◽  
pp. 209-217
Author(s):  
Serdar B. Yazyev ◽  
Stepan Litvinov ◽  
Anastasia E. Dudnik ◽  
Irina Doronkina
Keyword(s):  
Internal Pressure ◽  
Single Layer ◽  
Thermal Conditions ◽  
Thick Wall ◽  
Rheological Parameters ◽  
The Finite Element Method ◽  
One Dimensional ◽  
Cyclic Temperature ◽  
Temperature Dependences ◽  
Pvc Pipe

Rheologic of a polymer pipe from cyclic temperature and internal pressure in one-dimensional and two-dimensional formulations is considered. The resulting equations of the finite element method allow one to calculate both single-layer and multilayer thick-walled pipes taking into account creep. In the calculation, the temperature dependences of the elastic and rheological parameters of polymer pipes were used. The effect of variable thermal conditions on the VAT of a PVC pipe is investigated. It has been established that under unsteady thermal conditions, stresses can occur significantly higher than in a stationary temperature field. This is explained by the fact that polymers have a component of deformation that is lagging in phase from stresses (highly elastic deformation).

Ethical problems related to intravenous fluids in nursing homes

2014 ◽  
Vol 21 (8) ◽  
pp. 890-901 ◽  
Author(s):  
May-Elin T Horntvedt ◽  
Maria Romøren ◽  
Betty-Ann Solvoll
Keyword(s):  
Decision Making ◽  
Nursing Homes ◽  
Internal Pressure ◽  
Collaborative Research ◽  
Ethical Problem ◽  
Organizational Factors ◽  
External Pressure ◽  
Intravenous Fluids ◽  
Research Project ◽  
Ethical Problems

Background: Intravenous fluids and/or antibiotics are applied to only a limited extent in Norwegian nursing homes, and the patients are often sent to hospital in these situations. A transfer and a stay in hospital may be unnecessary strains for frail older patients. Given this background, a collaborative research project was initiated in a Norwegian county in 2009. A teaching programme was developed, which aimed to strengthen the awareness of ethics, assessments and practical procedures related to intravenous fluid and/or antibiotics among healthcare professionals. Objectives: This qualitative study aimed to increase our knowledge of the ethical problems experienced by nursing home nurses in situations related to the administration of intravenous fluids and/or antibiotics. Research design: An exploratory design was used, and five focus group interviews were conducted with 26 registered nurses. A hermeneutic analytic approach was applied. Ethical considerations: This study was reported to the Norwegian Social Science Data Services in May 2010. The Regional Committee for Medical and Health Research Ethics approved the collaborative research project. Findings: The analysis showed that the nurses experienced difficult decision-making situations, which were interpreted as external pressure and internal pressure. External pressure emerged in interactions with patients and relatives. Organizational factors were also interpreted as external pressure. Internal pressure was interpreted as the nurses’ experience of feeling inadequate in situations where it was difficult to protect the dignity of patients. Discussion: These findings correspond with international studies, which show that ethical problems often arise during decision-making situations. Conclusion: In agreement with the definition of an ethical problem, we found that the nurses experienced uncertainty and disagreements about how situations should be managed. External and internal pressures related to intravenous fluids and/or antibiotics in nursing homes have not been reported in previous studies. Thus, these findings merit further exploration.

Sign in / Sign up

Export Citation Format

Share Document