Pull-out experiments

Sastry, A.M., Phoenix S.L. and Schwartz, P. (1993). Analysis of interfacial failure in a composite microbundle pull-out experiment. Composites Sci. Technol. 48, 237-251. 

Load-displacement F-d) curves were recorded on a Zwick 1425 tensile-testing machine. Specimens for the double sided pull-out experiments were prepared as described in [11, 3],... 

It should be noted that for larger crack openings the first term in eq (15c)tends to zero for w=l/2, whereas the second term tends to zero for w=l/4, a factor previously mentioned in the literature. Pull-out experiments have shown to deminish due to polishing. Experiments by Bien and Stroeven [1] indicate the drop to be considerable. The first part of the post ultimate curve will therefore tend to zero for values below w l/4. This author has suggested a value of w=l/6, that is derived from eq (17) reorganized in the form... 

Whereas the main challenge for the first bilayer simulations has been to obtain stable bilayers with properties (e.g., densities) which compare well with experiments, more and more complex problems can be tackled nowadays. For example, lipid bilayers were set up and compared in different phases (the fluid, the gel, the ripple phase) [67,68,76,81]. The formation of large pores and the structure of water in these water channels have been studied [80,81], and the forces acting on lipids which are pulled out of a membrane have been measured [82]. The bilayer systems themselves are also becoming more complex. Bilayers made of complicated amphiphiles such as unsaturated lipids have been considered [83,84]. The effect of adding cholesterol has been investigated [85,86]. An increasing number of studies are concerned with the important complex of hpid/protein interactions [87-89] and, in particular, with the structure of ion channels [90-92]. 

To an appreciable degree the coupon experiences the same downhole conditions as the drillstring does. Therefore, its condition represents the corrosive effects of the downhole environment. However, limitations of this test are that the coupon is only exposed to the inside of the drillstring and not subject to the Same stresses. The results obtained are only for certain depth of exposure, while the corrosion may vary appreciably up and down the hole. Finally, the results are not available until the tool is pulled out of the hole. 

The overall experimental procedure for an initial detection of PatA binding proteins is schematically shown in Fig. 14.5. Thus, three parallel pull-down experiments were carried out simultaneously. The first is a control in which... 

Kim, J.K., Baillic, C. and Mai, Y.W. (1992). Fnterfacial debonding and fiber pull-out stresses, part F. A critical comparison of existing theories with experiments. J. Mater. Sci. 27, 3143-3154. 

Fig. 4.26. Comparisons between experiments and theory of (a) maximum debond stress, trj, and (b) initial frictional pull-out stress for carbon fiber-epoxy matrix composites. After Kim et al. (1992).

Eqs. (4.140) and (4.150)-(4.152) are used to evaluate the response of the model composites in cyclic loading and the displacements 6 and 8, can be expressed as a function of the alternating stress, Aff, and the number of cycles, N. In experiments, degradation of the interface properties, e.g., the coefficient of friction, p or A(= 2pjfc/a), can also be expressed in terms of the cyclic loading parameters, Aoptical methods (with a microscope) or by means of more complicated instruments (see for example Naaman et al. (1992)) in fiber pull-out. Alternatively, they can be directly determined from the load and load-point displacement records in the case of fiber push-out. 

They have cops at the exits. If they know you are skipping school, they won t let you out. So we just put two friends in the trunk and we would pull out. I start crying. I am like, I have to go home. I have emotional problems. [The police] would let us go and I would stop crying and start laughing. It was a funny experience. (Ashley freshman, aged 16)... 

Why is it that insects like beetles can walk on water Why do the bristles of a brush immersed in water cling together as the brush is pulled out Phenomena such as these arise because of a special property of interfaces that separate two phases. Let us consider another example first. Everyone has had the experience of pouring more beverage into a cup or glass than that container could hold. In addition to the spills this causes, such an experience provides an opportunity to observe surface tension. Most liquids can be added to a vessel until the liquid surface bulges above the rim of the container. The liquid behaves as if it had a skin that prevents it —up to a point —from overflowing. Stated technically, a contractile force, which tends to shrink the surface, operates around the perimeter of the surface. This is what we mean when we talk about the surface tension of a liquid. All phase boundaries behave this way, not just liquid surfaces however, the evidence for this is more apparent for deformable liquid surfaces. 

---