Introduction:
Objective:
• To determine the buckling load for a pinned ended strut.

Theory:
• The critical buckling load, Pcr, for a pinned ended strut is given by; Pcr = п² EI / (L²) [pic] Apparatus:
1. Vernier Caliper
2. Specimen
3. Steel Ruler
4. Allen Keys
5. Digital indicator

[pic]

Procedure:
1. Switch on the digital indictor and warm it up for at least 10 minutes. 2. Choose a specimen and measure its length. The width and thickness of the beam is 3 mm and 25 mm respectively. 3. Calculate the theoretical buckling load for a strut with pinned end condition. This is to ensure that the load applied to the strut does not exceed the buckling load. 4. Placed the grooved support into the slot of the attachment for the end conditions and tightened the side screws. Refer appendix for proper installation of the support. 5. Move the top platen upwards or downwards to bring the distance between the two supports closer to the length of the strut. 6. Press the tare button on the digital indicator to set the reading to zero. 7. Place the specimen in the groove of the top support.

8. While holding the specimen, adjust the jack so that the lower end of the specimen just rest in the groove of the bottom support. (If the distance between the two supports is slightly less than the length of the strut, turn the screw jack handle counter clockwise. If the distance between the two supports is slightly greater than the length of the strut, turn the screw jack handle clockwise. 9. Note the reading on the digital indicator. If the load is greater than 10 N turn the jack handle counter clockwise to bring it to less than 10 N. 10. Check the position of the dial gauge to ensure that it is at the mid length of the specimen. Set the dial gauge reading to zero. 11. Press the tare button to set the load indicator to zero. 12. Load the specimen in small increments by turning the screw jack handle slowly in the clockwise...

...IEEE TRANSACTIONS ON POWER DELIVERY, VOL. 29, NO. 1, FEBRUARY 2014
241
Analysis of Buckling Strength of Inner Windings in
Transformers Under Radial Short-Circuit Forces
Amit Bakshi and S. V. Kulkarni, Senior Member, IEEE
Abstract—The buckling of conductors of inner windings in
transformers is one of the major causes of their failures. It can
occur when a large magnitude of radial short-circuit electromagnetic force acts on them. In this paper, initially, mechanical strains
developed during winding processes and due to radial short-circuit forces have been determined. The two mechanical strains viz.
the short-circuit induced strain and the winding process-induced
strain are algebraically added to obtain their resulting strain.
The stress corresponding to the resulting strain has been determined by using the Ramberg–Osgood stress-strain relation. The
critical buckling stress has been calculated and compared with
the resulting stress. The analytically obtained result of the strain
induced in the winding conductor during its winding process has
been verified using the finite-element method. A case study has
been described in which the factor of safety against the buckling
strength is determined.
Index Terms—Buckling, short-circuit force, strain, stress,
transformers.
I. INTRODUCTION
P
OWER transformers should have sufficient mechanical
strength to withstand short-circuit...

...1
SAYI : 1
SAYFA : 39-43
SCIENCES
EXPERIMENTAL INVESTIGATION OF THE PHENOMENON OF
BUCKLING FOR STEEL AND ALUMINIUM STRUTS
Durmuş TÜRKMEN
University of Pamukkale, Engineering Faculty, Denizli -TURKEY
ABSTRACT
The experiment was carried out to investigate the phenomenon of buckling using simple struts. These results were then
compared with the theoretical predictions. Three steel struts of different length were used in the experiment; one of
them had fix/pinned-end all the others had pin/pin-end joint. The applied load was placed at different eccentricities for
each strut. Six aluminium pin-end struts of varying length were also tested. The measured critical load for each strut
was compared against the corresponding Euler and Southwell predictions. For a steel strut, it would be expected that
buckling would be symmetrical for left and right eccentricities. However, this was not the case due to imperfections in
the struts. The struts buckled with half sine-wave and if one end of the strut was fixed the effective length was reduced
and the critical load was increased. In the case of the aluminium struts, due to plastic behaviour in the deformation it
was much harder to find the critical load. For steel struts both Euler and Southwell predictions...

...Types of Buckling
Engineering is one discipline that is based on several different phenomenon and concepts. Each concept in engineering is as important as other and they all work together to give rise to some new techniques. One phenomenon that is extremely beneficial and widely used in engineering and science is buckling. Buckling is nothing but a phenomenon of mathematical instability, which leads to a special failure mode. When a system in equilibrium is subjected to additional load, it buckles down and gets deformed. This deformation is what is known as buckling. There are several different types of buckling that can take place in objects and those are described as below.
Flexural buckling is a special form of buckling that takes place in a special compression member facing a deflection because of the bending of flexure. It occurs mostly in a straight column when the stable equilibrium gets distorted at the critical load. The buckling is shown to occur mainly at the axis and demonstrates significantly small radius of gyration. There are different types of flexural buckling that can take place in objects and different equations can be employed for determining the load and the extent of buckling caused due to the same.
Lateral buckling is also commonly observed in objects when the deflection goes out of the plane in...

...www.elsevier.com/locate/ijsolstr
Buckling analysis of plain knitted fabric sheets under simple shear in an arbitrary direction
Y.T. Zhang
a b
a,*
, C.Y. Liu b, R.X. Du
b
Department of Mechanics, Tianjin University, Tianjin 300072, China Department of Automation and Computer-Aided Engineering, The Chinese University of Hong Kong, Hong Kong, China Received 22 December 2006; received in revised form 12 March 2007 Available online 30 March 2007
Abstract Knitting structures make plain knitted fabric diﬀerent from woven fabric. With the aid of a micro-constitutive model the buckling of a knitted fabric sheet subjected to simple shear in an arbitrary direction is investigated. The large deformation of the fabric sheet in its critical conﬁguration is considered. The theory of stability for ﬁnite deformations is applied to the analysis. All the stress boundary conditions of the knitted fabric sheet are satisﬁed. An equation for determining the buckling direction angle is derived. It is shown that there are two possible buckling modes: a ﬂexural mode and a barreling mode. The buckling conditions for the two modes are also obtained, respectively. A numerical calculation reveals that only the ﬂexural mode can occur, which agrees with experimental observations. Ó 2007 Elsevier Ltd. All rights reserved.
Keywords: Knitted fabric; Knitting structure; Buckling; Wrinkling; Simple shear...

...Higher Certificate in Civil Engineering
Subject : Structural Analysis I - Laboratory Report
Laboratory Venue : HKIVE (Tsing Yi), Room CL02
Date & Time : 15 October 2001, 19:00 to 20:15
Experiment No. 1 : Column Buckling Test
Objective:
1. To study the effect of support conditions on the load, carrying capacity of a slender column.
2. To compare the experimental buckling loads Pcr of test specimens with those predicted by the Euler equation.
Apparatus:
1. SM 105 strut apparatus (Issuing Voucher: 0203141 & Inventory Ledger: CN/s/01/10),
2. Aluminum bar specimen (20 x 3 x 600 mm approximate),
3. Measuring ruler,
4. Venier caliper.
Theory:
The factors affecting the column’s load – carrying capacity are the connection between the slenderness of the column and its tendency to buckle, the influence of the ‘fixity’ of the ends of the column, and the shape of its section on that slenderness.
When the line of action of the resultant load is coincident with the centre of gravity axis of the column (Fig. 1a), the column is said to be axially loaded and the stress produced in the material is said to be a direct compressive stress. This stress is uniform over the cross-section of the column. The term concentric loading is sometimes used instead of axial loading.
When the load is not axial, it is said to be eccentric (i.e. off-centre) and bending stress is induced in the column as well as a direct compressive stress (Fig. 1b). It has...

...columns to buckle. Equation 3 is the formula to find the adjusted stress using the SG values obtains from the experiment.
Procedures
Part One – Measurements
Retrieve 5 wooden samples of different length and measure and weight the wood samples. Next calculate the theoretical Euler buckling load and stress by using Equation 1 and Equation 2.
Part Two – Computer
Use the computer to control the compression machine, load the samples onto the machine, enter the require information on the computer, and press start.
Measure the Max stress and max load that the computer printout.
Analysis of Results
Graph 8.1 shows the transition from short columns, intermediate colums, and long columns. The transition shows whether the column get crushed, crushed and buckle, or just buckle. As the columns gets longer, they tend to buckle and fail at a lower load and as the colums gets shorter, they tend to get crushed and fail at the maximum crushing stress.
Conclusion
With the end of the experiments, multiple wooden columns were tested to find their behaviors on whether they buckle or get crushed. As the wooden beams get longer, they fail at lower loads because of the buckling phenomenon. The buckling direction is influenced by the grain structure of the wood and presence of defects in the materials.
...