Effect of joint stiffness and size on stability of three-way single-layer cylindrical reticular shell

2020 ◽  
Vol 35 (3) ◽  
pp. 90-107
Author(s):  
Hui-jun Li ◽  
Yoshiya Taniguchi
Keyword(s):  
Carrying Capacity ◽  
Joint Stiffness ◽  
Single Layer ◽  
Shear Stiffness ◽  
Limit Load ◽  
Torsional Stiffness ◽  
Axial Stiffness ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Joint Shear

The main aim of the present article is to study the effect of joint stiffness and joint size on load-carrying capacity of single-layer cylindrical reticular shell. One normalized joint bending stiffness index κb and three proposed normalized indexes, that is, normalized joint axial stiffness κa, normalized joint shear stiffness κs, and normalized joint torsional stiffness κt, are used to evaluate the stiffness of joint. Through a large number of numerical computations, the main conclusions are summarized as follows: κb has a significant effect on limit load of reticular shell, and this effect has a close relationship to rise-to-span ratio of reticular shell. If κb is larger than 30, the joint can be treated as rigid joint. The relationship between the logarithm of κb and limit load of reticular shell can be expressed by the logistic formulation. Overall rigidity and load-carrying capacity of reticular shell are greatly influenced by joint axial stiffness. If κa is larger than 30, the effect of joint axial stiffness on load-carrying capacity of reticular shell is no longer obvious. Otherwise, the load-carrying capacity will be markedly reduced. The relation between the logarithm of κa and limit load of reticular shell can be fitted by the Dose–response formulation. The load-carrying capacity of reticular shell is also influenced by joint torsional stiffness and joint shear stiffness to some extent. The relation between the logarithm of κs and limit load can be fitted by the Asymptotic formulation. The effect of joint size on overall rigidity and limit load of reticular shell is evident and cannot be neglected. The limit load gradually decreases with the decrease in joint size, and there is an approximate linear relationship between limit load and joint size.

scholarly journals CHARACTERIZATION OF ULTRASONIC ASSISTED ADHESIVE JOINTS

2016 ◽  
Vol 3 ◽  
pp. 52-55 ◽  
Author(s):  
Rainer Pauska ◽  
Umut Cakmak ◽  
Rainer Lottes ◽  
Zoltan Major
Keyword(s):  
Carrying Capacity ◽  
Adhesive Joints ◽  
Ultrasonic Waves ◽  
Load Carrying Capacity ◽  
Lap Joint ◽  
Shear Tests ◽  
Load Carrying ◽  
Ultrasonic Assisted ◽  
Joint Shear

Joining experiments using different adhesives were carried out. In addition to the adhesive, the specimens were also treated with ultrasonic waves to improve the load carrying capacity of the joined parts. Lap joint shear tests have been conducted to quantify this improvement.

Development of Z-Factor for Circumferential Part-Through Surface Cracks in Dissimilar Metal Welds

2008 ◽  
Author(s):  
D.-J. Shim ◽  
G. M. Wilkowski ◽  
D. L. Rudland ◽  
F. W. Brust ◽  
Kazuo Ogawa
Keyword(s):  
Correction Factor ◽  
Carrying Capacity ◽  
Limit Load ◽  
Maximum Load ◽  
Load Carrying Capacity ◽  
Surface Cracks ◽  
Crack Driving Force ◽  
Dissimilar Metal ◽  
Load Carrying ◽  
J Estimation

Section XI of the ASME Code allows the users to conduct flaw evaluation analyses by using limit-load equations with a simple correction factor to account elastic-plastic fracture conditions. This correction factor is called a Z-factor, and is simply the ratio of the limit-load to elastic-plastic fracture mechanics (EPFM) maximum-load predictions for a flaw in a pipe. The past ASME Section XI Z-factors were based on a circumferential through-wall crack in a pipe rather than a surface crack. Past analyses and pipe tests with circumferential through-wall cracks in monolithic welds showed that the simplified EPFM analyses (called J-estimation schemes) could give good predictions by using the toughness, i.e., J-R curve, of the weld metal and the strength of the base metal. The determination of the Z-factor for a dissimilar metal weld (DMW) is more complicated because of the different strength base metals on either side of the weld. This strength difference can affect the maximum load-carrying capacity of the flawed pipe by more than the weld toughness. Recent work by the authors for circumferential through-wall cracks in DMWs has shown that an equivalent stress-strain curve is needed in order for the typical J-estimation schemes to correctly predict the load carrying capacity in a cracked DMW. In this paper, the Z-factors for circumferential surface cracks in DMW were determined. For this purpose, a material property correction factor was determined by comparing the crack driving force calculated from the J-estimation schemes to detailed finite element (FE) analyses. The effect of crack size and pipe geometry on the material correction factor was investigated. Using the determined crack-driving force and the appropriate toughness of the weld metal, the Z-factors were calculated for various crack sizes and pipe geometries. In these calculations, a ‘reference’ limit-load was determined by using the lower strength base metal flow stress. Furthermore, the effect of J-R curve on the Z-factor was investigated. Finally, the Z-factors developed in the present work were compared to those developed earlier for through-wall cracks in DMWs.

THE ABILITY OF NANOCOMPOSITE CARBON COATINGS TO WITHSTAND FRICTION UNDER SEVERE CONDITIONS

Tribologia ◽  
2019 ◽  
Vol 287 (5) ◽  
pp. 115-124
Author(s):  
Sławomir ZIMOWSKI ◽  
Marcin KOT ◽  
Grzegorz WIĄZANIA ◽  
Tomasz MOSKALEWICZ
Keyword(s):  
Carrying Capacity ◽  
Steel Substrate ◽  
Point Contact ◽  
Limit Load ◽  
Scratch Test ◽  
Load Carrying Capacity ◽  
Indentation Method ◽  
Wear Process ◽  
Tribological Tests ◽  
Load Carrying

The paper presents an analysis of the micromechanical properties of selected thin, hard anti-wear coatings of the type nc-TiN/a-C and nc-TiC/a-C, which were deposited by magnetron sputtering on a steel substrate. The load carrying capacity of the nanocomposite coatings was analysed in point contact with the use of indentation method, a scratch test, and friction test in contact with a ceramic ball. The hardness and modulus of elasticity of the coatings were determined by an instrumented indentation method using a Vickers indenter. The coating adhesion to the substrate was examined in a scratch test. Tribological tests in sliding contact with an Al2O3 ball were made at various loads to determine the limit load in which normal friction occurs. The results of tribological tests were compared with the resistance to plastic deformation index (H3/E2). It was found that the basic micromechanical parameters of coatings provide important information concerning durability and load carrying capacity. However, while predicting wear, it is also important to investigate the nature of the wear process during friction. The wear nature of the nc-TiN/a-C and nc-TiC/a-C coatings depends on the load value and the number of forced loads.

Determination of Limit Load Solution for the Remaining Load-Carrying Capacity of Corroded Pipelines

2016 ◽  
Vol 138 (5) ◽  
Author(s):  
Mechri Abdel Ghani ◽  
Ghomari Tewfik ◽  
Djouadi Djahida
Keyword(s):  
Carrying Capacity ◽  
High Strength ◽  
Limit Load ◽  
Plastic Instability ◽  
Instability Criterion ◽  
Burst Pressure ◽  
Average Error ◽  
Strain Hardening Exponent ◽  
Load Carrying Capacity ◽  
Load Carrying

The evaluation of pipelines having external corrosion defect and their remaining load-carrying capacity is a concern which becomes important in energy industry, especially with the increasing operating pressures and the consequences which can occur following the bursting of these pipelines. A lower bound analytical solution for the prediction of the burst pressure of pipelines is proposed. This solution is based on the approach of plastic-instability criterion in terms of material strain-hardening exponent of internally pressurized corroded pipelines. The suggested solution is evaluated by using database comprising more than 100 carried out tests of pipelines with or without corrosion defects. This database is collected from the literature and covers the majority of steel materials as well as the various standard sizes. The accuracy of the proposed solution is compared with B31.G method and its improved version B31.G Mod by using statistical analyses in terms of average error and its correspondent standard deviation. The proposed solution is accurate than B31.G and modified B31.G methods that are conservative and provide in some cases of middle and high strength material an overestimated burst pressure predictions.

Limit Load Analysis of Cylindrical Vessels Under Internal Pressure and Axial Strain

2011 ◽  
Author(s):  
Xian-Kui Zhu
Keyword(s):  
Internal Pressure ◽  
Carrying Capacity ◽  
Pressure Vessel ◽  
Axial Strain ◽  
Limit State ◽  
Limit Load ◽  
Operating Pressure ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Load Analysis

Strain-based design is a newer technology used in safety design and integrity management of oil and gas pipelines. In a traditional stress-based design, the axial stress is relatively small compared to the hoop stress generated by internal pressure in a line pipe, and the limit state in the pipeline is usually load-controlled. In a strain-based design, however, axial strain can be large and the load-carrying capacity of pipelines could be reduced significantly below an allowed operating pressure, where the limit state is controlled by an axial strain. In this case, the limit load analysis is of great importance. The present paper confirms that the stress, strain and load-carrying capacity of a thin-walled cylindrical pressure vessel with an axial force are equivalent those of a long pressurized pipeline with an axial tensile strain. Elastic stresses and strains in a pressure vessel are then investigated, and the limit stress, limit strain and limit pressure are obtained in terms of the classical Tresca criterion, von Mises criteria, and a newly proposed average shear stress yield criterion. The results of limit load solutions are analyzed and validated using typical experimental data at plastic yield.

Stability of cable-supported spherical reticulated shell with tension members

2020 ◽  
Vol 35 (3) ◽  
pp. 69-79
Author(s):  
Zhen Lu ◽  
Hui-jun Li ◽  
Chao Wang
Keyword(s):  
Carrying Capacity ◽  
Single Layer ◽  
Buckling Analysis ◽  
Load Carrying Capacity ◽  
Geometric Imperfection ◽  
Tension Member ◽  
Load Carrying ◽  
Initial Geometric Imperfection ◽  
Asymmetric Load ◽  
Tension Members

The suspendome has been widely employed in large-span space structures in recent years, and it has stronger structural stiffness and higher load-carrying capacity than single-layer spherical reticulated shell. In general, it is negligible for enhancement of load-carrying capacity to integrate cables and struts into the inner ring of reticulated shell. Based on the suspendome structure, a new hybrid space structure system, namely, cable-supported reticulated shell with tension member, is proposed in this study. To elucidate and verify its feasibility, the buckling mode and buckling form are obtained by the eigenvalue buckling analysis and nonlinear buckling analysis using ANSYS package, respectively. Furthermore, to determine the optimal structural form, this article investigates the effect of the main ribbed strut length, the initial geometric imperfection, asymmetric load, pretension in cables, and the material nonlinearity on its stability. The result shows that the proposed new structural system is of high load-carrying capacity. Tension member integrated to cable-supported reticulated shell can effectively improve the overall stiffness and greatly reduce the deformation of spherical reticulated shell. The plastic failure shape occurs with the similar pattern. The instable region mainly occurs on the main ribs with tension members, and each main rib only has one local failure dimple. The load-carrying capacity is remarkably affected by the asymmetric load, the initial geometric imperfection, and material nonlinearity. Based on the parametric analyses, Type C is the optimal choice, that is, appending cables and struts to the outermost ring of single-layer spherical reticulated shell, and arranging out-of-plane tension members under the four main ribs.

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