Buckling of a Rectangular Frame Revisited

1987 ◽  
Vol 54 (3) ◽  
pp. 617-622
Author(s):  
P. Seide
Keyword(s):  
Limit Load ◽  
Bending Stiffness ◽  
Stiffness Ratio ◽  
Stiffness Parameter ◽  
Rotational Stiffness ◽  
Height Ratio ◽  
Rectangular Frame ◽  
Uniform Beam ◽  
Symmetrical Deformation ◽  
Deformation Limit

An investigation of the buckling under uniform beam load of a rectangular frame with columns restrained by linear rotational springs indicates that for certain ranges of bending stiffness ratio, length-height ratio, and support rotational stiffness parameter, the antisymmetrical bifurcation mode of buckling does not exist and buckling occurs at a symmetrical deformation limit load. The ranges of parameters for which this phenomenon may be important are studied.

Method of Bending Stiffness Parameter Identification of Stay Cable

2015 ◽  
Vol 777 ◽  
pp. 52-58
Author(s):  
Hong Du ◽  
Da Yang Liu ◽  
Fu Wei Huang ◽  
Jing Bo Liao
Keyword(s):  
Parameter Identification ◽  
Bending Stiffness ◽  
Parameters Identification ◽  
Stiffness Ratio ◽  
Stiffness Parameter ◽  
Stay Cable ◽  
Cable Tension ◽  
Cable Length

In order to solve the problem of bending stiffness parameters identification of practical stay-cable, and provide bending stiffness correction for tension measurement. A method to identify cable bending stiffness parameters is proposed, and its basis theory established in paper. The method was applied to Xiazhang Sea-Crossing Bridge, the results showed that: Identification bending stiffness ratio is between 0.33 to 0.54 for relatively short cables of South Branch Bridge, and it tends to decrease with increase of cable length and force. However, the identification bending stiffness is close or equal to 0 EImax for relatively long cable of North Branch Bridge. It testified that the effect of bending stiffness for long cable tension is small in engineering.

Vibrations of an Intermediately Supported U-Bend Tube

1975 ◽  
Vol 97 (1) ◽  
pp. 23-32 ◽  
Author(s):  
L. S. S. Lee
Keyword(s):  
Natural Frequency ◽  
Natural Frequencies ◽  
Experimental Tests ◽  
Bending Stiffness ◽  
Stiffness Ratio ◽  
Plane Vibration ◽  
Straight Beam ◽  
Out Of Plane ◽  
Straight Segments ◽  
Good Agreement

Vibrations of an intermediately supported U-bend tube fall into two independent classes as an incomplete ring of single span does, namely, the in-plane vibration and the coupled twist-bending out-of-plane vibration. Natural frequencies may be expressed in terms of a coefficient p which depends on the stiffness ratio k, the ratio of lengths of spans, and the supporting conditions. The effect of the torsional flexibility of a curved bar acts to release the bending stiffness of a straight beam and hence decrease the natural frequency. Some conclusions for an incomplete ring of single span may not be equally well applicable to the U-tube case due to the effects of intermediate supports and the presence of the supporting straight segments. Results of the analytical predictions and the experimental tests of an intermediately supported U-tube are in good agreement.

scholarly journals Swelling-induced wrinkling in layered gel beams

2017 ◽  
Vol 473 (2207) ◽  
pp. 20170454 ◽  
Author(s):  
P. Nardinocchi ◽  
E. Puntel
Keyword(s):  
Perturbation Analysis ◽  
Biomedical Applications ◽  
Finite Strain ◽  
Parameter Plane ◽  
Linear Perturbation ◽  
Stiffness Ratio ◽  
Height Ratio ◽  
Mechanical Stiffness ◽  
Total Height ◽  
Mechanical Devices

Gels are widely employed in smart mechanical devices and biomedical applications. Swelling-induced bending actuation can be obtained by means of a simple bilayer gel beam. We show that this system can also exhibit wrinkling patterns of potential interest for structural morphing and sensing. We study swelling-induced wrinkling at the extrados of a bilayer gel beam with the softer layer on top. The bent configuration at finite strain is recovered first and, starting from it, a linear perturbation analysis is performed. We delimit the zone corresponding to wrinkling modes in a parameter plane encompassing a mechanical stiffness ratio and a geometric top layer to total height ratio. Interestingly, we observe that surface instability precedes and envelopes wrinkling modes of finite wavelength. Finally, we discuss the effect of changes in stiffness and of the Flory–Huggins parameters χ on the size of the wrinkling domain.

Soil Arching over Deeply Buried Thermoplastic Pipe

2003 ◽  
Vol 1849 (1) ◽  
pp. 109-123 ◽  
Author(s):  
Shad M. Sargand ◽  
Teruhisa Masada
Keyword(s):  
Strain Gauge ◽  
Bending Stiffness ◽  
Field Soil ◽  
Stiffness Parameter ◽  
Soil Pressure ◽  
Buried Pipe ◽  
Soil Arching ◽  
Pressure Cell

Soil arching associated with buried thermoplastic pipe is discussed. First, the soil arching phenomenon is described. Then two different approaches are mentioned from the literature to represent the degree of soil arching (or vertical arching factor). The elastic solutions of Burns and Richard are revisited to derive expressions for the vertical soil arching factor for buried pipe. Comparison of the elastic solutions and field soil pressure cell readings reveals the importance of incorporating a bending stiffness parameter. With this finding, the AASHTO method for calculating the load on buried pipe is evaluated against the elastic solutions. The analysis reveals that the AASHTO method is conservative, overestimating the load on thermoplastic pipe by up to 30%. Further evidence to support the finding is found within the strain gauge readings taken on the pipe walls in the field. Therefore, alternative equations derived directly from the elastic solutions are recommended to predict the load on buried thermoplastic pipe instead of the AASHTO method.

The Mechanical Properties of Origami Structure Determined by the Improved Virtual Crease Method

2021 ◽  
Vol 13 (01) ◽  
pp. 2150002
Author(s):  
Wei Wang ◽  
Xinming Qiu
Keyword(s):  
Mechanical Properties ◽  
Large Deformation ◽  
Strain Energy ◽  
Coupling Effect ◽  
Coupling Factor ◽  
Bending Stiffness ◽  
Rotational Stiffness ◽  
Coupling Problem ◽  
Shell Deformation

The mechanical properties and deformation of Origami structures are studied in this paper. Usually, it is a coupling problem of crease rotation and shell deformation. Here, the creases are simplified as torsional springs, whose rotational stiffness [Formula: see text] is obtained by the experiment of compressing a creased shell. While the shells that may have large deformation are simplified as rigid plates connected by virtual creases, whose rotational stiffness is roughly expressed as bending stiffness divides width of the shell. Hence, a coupling factor [Formula: see text] is defined to evaluate the coupling effect of creases and shells. Implementing the obtained rotational stiffnesses of real and virtual creases into the expression of strain energy, an improved Virtual Crease Method (VCM) is proposed. By analyzing the bi-stability of creased shell and Miura-Ori structure, the accuracy and convergence of this improved VCM is proved.

Research on Out-Plane Bending Stiffness of Multi-Ribbed Slab Structure

2013 ◽  
Vol 838-841 ◽  
pp. 597-600
Author(s):  
Hai Jun Yuan ◽  
Lang Cao ◽  
Liang Hao Deng
Keyword(s):  
Bending Moment ◽  
Shear Wall ◽  
Bending Stiffness ◽  
Equivalent Stiffness ◽  
Height Ratio ◽  
Stiffness Method ◽  
Plane Bending ◽  
Large Width

Floor loads of the large-bay floor can cause larger bending moment at the floor edges. So the shear-wall need to bear greater out-plane bending moment and this problem can not be ignored. multi-ribbed slab structure is a new wall. The paper Calculated out-plane bending-stiffness of multi-ribbed slab by using the equivalent-stiffness method. The results show that: the equivalent stiffness method is simple and ribbs should not be too large, width-height ratio control between 1 and 3, wall length is about 5.4m.

A Predictive Model for the Fabric-to-Yarn Bending Stiffness Ratio of a Plain-Woven Set Fabric

2000 ◽  
Vol 70 (12) ◽  
pp. 1088-1096 ◽  
Author(s):  
S.V. Lomov ◽  
A.V. Truevtzev ◽  
C. Cassidy
Keyword(s):  
Predictive Model ◽  
Bending Stiffness ◽  
Stiffness Ratio

The use of bioabsorbable screws to fix Type II odontoid fractures: a biomechanical study

2011 ◽  
Vol 15 (4) ◽  
pp. 361-366 ◽  
Author(s):  
Ali Nourbakhsh ◽  
Shashikant Patil ◽  
Prasad Vannemreddy ◽  
Alan Ogden ◽  
Debi Mukherjee ◽  
...  
Keyword(s):  
Screw Fixation ◽  
Bending Stiffness ◽  
Type Ii ◽  
Rotational Stiffness ◽  
Odontoid Fractures ◽  
Lag Screw ◽  
Anterior Screw Fixation ◽  
Titanium Screws ◽  
Bioabsorbable Screws ◽  
Screw Group

Object Anterior screw fixation of the Type II odontoid fracture stabilizes the odontoid without restricting the motion of the cervical spine. The metal screw may limit bone remodeling because of stress shielding (if not placed properly) and limit imaging of the fracture. The use of bioabsorbable screws can overcome such shortcomings of the metal screws. The purpose of this study was to compare the strength of a 5-mm bioabsorbable screw with single 4-mm metal and double 3.5-mm lag screw fixation for Type II fractures of the odontoid process. Methods Three different modalities of anterior screw fixation were used in 19 C-2 vertebrae. These fixation methods consisted of a single 5-mm cannulated bioabsorbable lag screw (Group A), a single 4-mm cannulated titanium lag screw (Group B), and two 3.5-mm cannulated titanium lag screws (Group C). Anteroposterior (AP) stiffness and rotational stiffness were evaluated in all constructs. Results There was no statistical difference among the ages of the cadavers in each group (p = 0.52). The AP bending stiffness in Groups A, B, and C was 117 ± 86, 66 ± 43, and 305 ± 130 Nm/mm, respectively. The AP bending stiffness in Group C was significantly higher than that in Groups A and B (p = 0.01 and p = 0.001, respectively). The difference in AP bending stiffness values of bioabsorbable and 4-mm metal screws was not statistically significant (p = 0.23). The rotational stiffness of the double 3.5-mm metal screws was significantly greater than that of the 5-mm bioabsorbable and the 4-mm titanium screws. Conclusions Double screw fixation with 3.5-mm screws provides the stiffest construct in Type II odontoid fractures. Bioabsorbable lag screws (5 mm) have the same AP bending and rotational stiffness as the single titanium lag screw (4 mm) in odontoid fractures.

Design of a Compliant Hinge Based on Closed Form Pressure Balancing

2020 ◽  
Author(s):  
Robin F. P. Gomes ◽  
Joep P. A. Nijssen ◽  
Ron A. J. van Ostayen
Keyword(s):  
Closed Form ◽  
Elastic Deformation ◽  
Compliant Mechanisms ◽  
State Of The Art ◽  
3D Analysis ◽  
Stiffness Ratio ◽  
Rotational Stiffness ◽  
Fluid Medium ◽  
Form Pressure ◽  
Rotation Stiffness

Abstract Compliant mechanisms consist of a monolithic body and obtain motion through elastic deformation. Multiple compliant flexure designs are known but their translational to rotation stiffness ratio is often limited. This work introduces a novel compliant hinge design with increased stiffness ratio compared to the state of the art compliant hinges. The hinge functions by having an encapsulated fluid medium that contributes to high normal stiffness, but doesn’t influence the rotational stiffness. A 2D design model is presented that shows the effect of the geometry on the stiffness ratio performance. Subsequently, a computational 3D analysis is performed and the resulting design is realized as a demonstrator. The performance is compared to conventional compliant hinges based on the stiffness ratio. This shows an increase of at least a factor 30 on the stiffness ratio.

Facial width-to-height ratio predicts testosterone-linked traits and behaviors

2014 ◽  
Author(s):  
Shelley S. Devens ◽  
Frank J. Bernieri ◽  
Katy L. Krieger
Keyword(s):  
Height Ratio ◽  
And Behaviors
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