scholarly journals Ruga mechanics of creasing: from instantaneous to setback creases

2013 ◽  
Vol 469 (2157) ◽  
pp. 20120753 ◽  
Author(s):  
Mazen Diab ◽  
Teng Zhang ◽  
Ruike Zhao ◽  
Huajian Gao ◽  
Kyung-Suk Kim
Keyword(s):  
Phase Diagram ◽  
Compressive Strain ◽  
Elastic Stiffness ◽  
Solid Surfaces ◽  
Decay Length ◽  
Stretchable Electronics ◽  
Bifurcation Stability ◽  
Strain Limit ◽  
Admissible Perturbation ◽  
Perturbation Wavelength

We present mechanics of surface creasing caused by lateral compression of a nonlinear neo-Hookean solid surface, with its elastic stiffness decaying exponentially with depth. Nonlinear bifurcation stability analysis reveals that neo-Hookean solid surfaces can develop instantaneous surface creasing under compressive strains greater than 0.272 but less than 0.456. It is found that instantaneous creasing is set off when the compressive strain is large enough, and the longest-admissible perturbation wavelength relative to the decay length of the elastic modulus is shorter than a critical value. A compressive strain smaller than 0.272 can only trigger bifurcation of a stable wrinkle that can prompt a setback crease upon further compression. The minimum compressive strain required to develop setback creasing is found to be 0.174. If the relative longest-admissible perturbation wavelength is long enough, then the wrinkle can fold before it creases, and the specimen can be compressed further beyond the Biot critical strain limit of 0.456. Various bifurcation branches on a plane of normalized longest-admissible wavelength versus compressive strain delineate different phases of corrugated surface configurations to form a ruga phase diagram. The phase diagram will be useful for understating surface crease, as well as for controlling ruga structures for various applications, such as designing stretchable electronics.

Required Linepipe Properties for High Strain Applications and Possible Resolution by Pipe Manufacturing Technology

2008 ◽  
Author(s):  
Hitoshi Asahi ◽  
Eiji Tsuru
Keyword(s):  
Tensile Strain ◽  
Compressive Strain ◽  
Bending Moment ◽  
Uniaxial Tensile ◽  
Buckling Behavior ◽  
Strain Limit ◽  
Bent Pipe ◽  
Uniaxial Tensile Stress ◽  
The Relationship ◽  
Pipe Manufacturing

Application of strain based design to pipelines in arctic or seismic areas has recently been recognized as important. So far, there has been much study performed on tensile strain limit and compressive strain limit. However, the relationship between bending buckling (compressive strain limit) and tensile strain limit has not been discussed. A model using actual stress strain curves suggests that the tensile strain limit increases as Y/T rises under uniaxial tensile stress because a pipe manufacturer usually raises TS instead of lowering YS to achieve low Y/T. Under bending of a pipe with a high D/t, an increase in compressive strain on intrados of a bent pipe at the maximum bending moment (ε-cp*) improves the tensile strain limit because the tensile strain limit is controlled by the onset of buckling or ε-cp* which is increased by lowering Y/T. On the other hand, under bending of a pipe with a low D/t, the tensile strain limit may not be influenced by improvement of buckling behavior because tensile strain on the extrados is already larger than the tensile limit at ε-cp*. Finally, we argue that the balance of major linepipe properties is important. Efforts other than the strict demands for pipe properties are also very important and inevitable to improve the strain capacity of a pipeline.

scholarly journals Anomalous Interfacial Structuring of a Non-Halogenated Ionic Liquid: Effect of Substrate and Temperature

2018 ◽  
Vol 2 (4) ◽  
pp. 60 ◽  
Author(s):  
Milad Radiom ◽  
Patricia Pedraz ◽  
Georgia Pilkington ◽  
Patrick Rohlmann ◽  
Sergei Glavatskih ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Surface Charge ◽  
Force Measurement ◽  
Surface Force ◽  
Solid Surfaces ◽  
Effect Of Temperature ◽  
Decay Length ◽  
Force Microscopy ◽  
Large Size ◽  
Atomic Force

We investigate the interfacial properties of the non-halogenated ionic liquid (IL), trihexyl(tetradecyl)phosphonium bis(mandelato)borate, [P6,6,6,14][BMB], in proximity to solid surfaces, by means of surface force measurement. The system consists of sharp atomic force microscopy (AFM) tips interacting with solid surfaces of mica, silica, and gold. We find that the force response has a monotonic form, from which a characteristic steric decay length can be extracted. The decay length is comparable with the size of the ions, suggesting that a layer is formed on the surface, but that it is diffuse. The long alkyl chains of the cation, the large size of the anion, as well as crowding of the cations at the surface of negatively charged mica, are all factors which are likely to oppose the interfacial stratification which has, hitherto, been considered a characteristic of ionic liquids. The variation in the decay length also reveals differences in the layer composition at different surfaces, which can be related to their surface charge. This, in turn, allows the conclusion that silica has a low surface charge in this aprotic ionic liquid. Furthermore, the effect of temperature has been investigated. Elevating the temperature to 40 °C causes negligible changes in the interaction. At 80 °C and 120 °C, we observe a layering artefact which precludes further analysis, and we present the underlying instrumental origin of this rather universal artefact.

Phase Diagram and Electronic Properties of High-TcSuperconducting Oxides

2003 ◽  
Vol 17 (10n12) ◽  
pp. 393-399
Author(s):  
Davor Pavuna
Keyword(s):  
Phase Diagram ◽  
Fermi Level ◽  
Compressive Strain ◽  
Flat Band ◽  
Brillouin Zone Boundary ◽  
Open Questions ◽  
Electronic Phase ◽  
Fermi Edge ◽  
Band Crossing ◽  
Strained Films

We firstly briefly summarize some of the most relevant recent results and open questions across rather complex electronic phase diagram of cuprates. We continue with a discussion of results on thin superconducting oxide films grown by laser ablation. Systematic studies show that BSCCO-phases and LSCO-214 exhibit conductor-like Fermi edge, whereas materials containing "chains" (like YBCO-123) are prone to very rapid surface degradation, most likely related to critical oxygen loss at the outermost layers. Recently, direct ARPES dispersion measurements on in-situ grown, strained 10UC thin LSCO-214 films (Tc= 44 K ) have shown the band crossing of Fermi level well before the Brillouin zone boundary. This is in contrast to the flat band observed in unstrained single crystals — and to the band flattening predicted by band calculations for in-plane compressive strain. In spite of density of states reduction near the Fermi level, the critical temperature increases in strained films with respect to unstrained crystals; this poses further challenge to HTSC theory.

Analytical Approach for Buckling Resistance of UOE Linepipe With Orthogonal Anisotropy Under Combined Loading

2010 ◽  
Author(s):  
Eiji Tsuru ◽  
Jun Agata ◽  
Yukinobu Nagata
Keyword(s):  
Mechanical Properties ◽  
Thermal Aging ◽  
Compressive Strain ◽  
Yield Function ◽  
Combined Loading ◽  
Long Distance ◽  
Strain Limit ◽  
Buckling Resistance ◽  
High Internal Pressure ◽  
Orthogonal Anisotropy

UOE linepipes have orthotropic work hardening in which the longitudinal (L-) stress vs. strain (SS) curve is different from the circumferential (C-) one. The anisotropy is emphasized by the thermal aging during the anti-corrosion coating. However, there are few studies on the effect of the circumferential mechanical properties on the compressive strain limit required in strain-based design (SBD). This paper describes the combined effect of SS curves in L- and the C-direction on the buckling resistance using the newly developed yield function to model the orthogonal anisotropy. The coupon tests after thermal aging during the anti-corrosion coating indicate that the L-SS curve can maintain the round-house type while the long yield point elongation (YPE) appears on the C-SS curve. Using these mechanical properties, FE-models demonstrate that YPE in the C-direction reduces the compressive strain limit for pipes with high diameter/thickness (D/t) under high internal pressure. Hence, SS curves in the C-direction should be considered for more reliable prediction of the buckling resistance required in long distance gas pipelines.

Buckling and Tensile Strain Capacity of Girth Welded 48″ X80 Pipeline

2013 ◽  
Author(s):  
Satoshi Igi ◽  
Mitsuru Ohata ◽  
Takahiro Sakimoto ◽  
Junji Shimamura ◽  
Kenji Oi
Keyword(s):  
Crack Growth ◽  
Tensile Strain ◽  
Compressive Strain ◽  
Bending Test ◽  
Ductile Crack ◽  
Pipe Surface ◽  
Strain Capacity ◽  
Ductile Crack Growth ◽  
Strain Limit ◽  
Tensile Strain Capacity

This paper presents the experimental and analytical results focused on the compressive and tensile strain capacity of X80 linepipe. A full-scale bending test of girth welded 48″ OD X80 linepipes was conducted to investigate the compressive strain limit regarding to the local buckling and tensile strain limit regarding to the girth weld fracture. As for the compressive buckling behavior, one large developing wrinkle and some small wrinkles on the pipe surface were captured relatively well from observation and strain distribution measurement after pipe reaches its endurable maximum bending moment. The tensile strain limit is discussed from the viewpoint of competition of two fracture phenomena: ductile crack initiation / propagation from an artificial notch at the HAZ of the girth weld, and strain concentration and necking / rupture in the base material. The ductile crack growth behavior from the girth weld notch is simulated by FE-analysis based on the proposed damage model, and compared with the experimental results. In this report, it is also demonstrated that the simulation model can be applicable to predicting ductile crack growth behaviors from a circumferentially notched girth welded pipe with internal high pressure subjected to post-buckling loading.

scholarly journals Buckling of a stiff thin film on an elastic graded compliant substrate

2017 ◽  
Vol 473 (2208) ◽  
pp. 20170410 ◽  
Author(s):  
Zhou Chen ◽  
Weiqiu Chen ◽  
Jizhou Song
Keyword(s):  
Thin Film ◽  
Analytical Model ◽  
Compressive Strain ◽  
Period Doubling ◽  
Stretchable Electronics ◽  
Element Analysis ◽  
Compliant Substrate ◽  
Material Parameters ◽  
Plane Compression ◽  
Critical Buckling Strain

The buckling of a stiff film on a compliant substrate has attracted much attention due to its wide applications such as thin-film metrology, surface patterning and stretchable electronics. An analytical model is established for the buckling of a stiff thin film on a semi-infinite elastic graded compliant substrate subjected to in-plane compression. The critical compressive strain and buckling wavelength for the sinusoidal mode are obtained analytically for the case with the substrate modulus decaying exponentially. The rigorous finite element analysis (FEA) is performed to validate the analytical model and investigate the postbuckling behaviour of the system. The critical buckling strain for the period-doubling mode is obtained numerically. The influences of various material parameters on the results are investigated. These results are helpful to provide physical insights on the buckling of elastic graded substrate-supported thin film.

Phase diagram for nanodroplet impact on solid surfaces

2021 ◽  
Vol 33 (10) ◽  
pp. 102007
Author(s):  
Qiang Ma ◽  
Yi-Feng Wang ◽  
Yi-Bo Wang ◽  
Xin He ◽  
Shao-Fei Zheng ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Solid Surfaces

scholarly journals Ruga-formation instabilities of a graded stiffness boundary layer in a neo-Hookean solid

2014 ◽  
Vol 470 (2168) ◽  
pp. 20140218 ◽  
Author(s):  
Mazen Diab ◽  
Kyung-Suk Kim
Keyword(s):  
Boundary Layer ◽  
Half Space ◽  
Compressive Strain ◽  
Three Dimensional ◽  
Decay Length ◽  
Element Analysis ◽  
Dimensional Parameter ◽  
First Order ◽  
Homogeneous Half Space ◽  
Lateral Plane

We present an analysis of ruga-formation instabilities arising in a graded stiffness boundary layer of a neo-Hookean half space, caused by lateral plane-strain compression. In this study, we represent the boundary layer by a stiffness distribution exponentially decaying from a surface value Q 0 to a bulk value Q B with a decay length of 1/ a . Then, the normalized perturbation wavenumber, k ¯ = k / a , and the compressive strain, ε , control formation of a wrinkle pattern and its evolution towards crease or fold patterns for every stiffness ratio η = Q B / Q 0 . Our first-order instability analysis reveals that the boundary layer exhibits self-selectivity of the critical wavenumber for nearly the entire range of 0< η <1, except for the slab ( η =0) and homogeneous half-space ( η =1) limits. Our second-order analysis supplemented by finite-element analysis further uncovers various instability-order-dependent bifurcations, from stable wrinkling of the first order to creasing of the infinite-order cascade instability, which construct diverse ruga phases in the three-dimensional parameter space of ( ε , k ¯ , η ) . Competition among film-buckling, local film-crease and global substrate-crease modes of energy release produces diverse ruga-phase domains. Our analysis also reveals the subcritical crease states of the homogeneous half space. Our results are, then, compared with the behaviour of equivalent bilayer systems for thin-film applications.

Comparison of Compressive Strain Limit Equations

2014 ◽  
Author(s):  
Nader Yoosef-Ghodsi ◽  
Istemi Ozkan ◽  
Qishi Chen
Keyword(s):  
Compressive Strain ◽  
Local Buckling ◽  
Strain Curve ◽  
Full Scale ◽  
Structural Testing ◽  
Slope Instability ◽  
Ground Movement ◽  
Movement Experience ◽  
Strain Limit ◽  
Key Variables

Buried pipelines subjected to non-continuous ground movement such as frost heave, thaw settlement, slope instability and seismic movement experience high compressive strains that can cause local buckling (or wrinkling). In the context of strain-based design, excessive local buckling deformation that may cause loss of serviceability, or even pressure containment in some cases, is managed by limiting the strain demand below the strain limit. The determination of compressive strain limit is typically performed by full-scale structural testing or nonlinear finite element analysis that takes into account material and geometric non-linearity associated with the inelastic buckling of cylindrical shells. Before performing testing and numerical analysis (or when such options do not exist), empirical equations are used to estimate the strain limit. In this paper a number of representative equations were evaluated by comparing strain limit predictions to full-scale test results. Work prior to this study has identified the importance of key variables that have the greatest impact on the local buckling behaviour. Examples of these variables include the diameter-to-thickness ratio (D/t), internal pressure and shape of the stress strain curve. The evaluation presented here focused on how existing equations address these key variables, and the performance of the equations with respect to key variables and in different ranges.

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