Multilayer mechanical analysis

Experiments were conducted to measure the stiffness of an IPMC beam and two IPMC-PVDF composite beams with different insulating layer thickness (30 pm vs. 100 pm). The two composite beams were named IPMC/PVDFl and IPMC/PVDF2, respectively. As illustrated in Fig. 8.5(a), the cantilevered beam under measurement was pushed quasi-statically at the tip by a linear actuator. Between the linear actuator and the tip was a PVDF-based micro force sensor measuring the interaction force. The tip displacement was measured with a laser distance sensor. Fig. 8.5(b) shows the measured tip displacement together with the corresponding force for each beam, with the spring constants determined to 

The measured spring constants were used in conjunction with (8.3) to obtain the (effective) Young s moduli of individual layers E = 0.571 GPa, E2 = 0.73 GPa, Es = 1.96 GPa, which are within the ranges reported in the literature [Sakakibara et al. (1994) Siripong et al. (2006)]. We then used these parameters together with the beam dimensions to perform finite element analysis. Based on the computed free-end deflection imder a tip force of 20 /xN, we got the spring constants of 0.908, 2.286, and 4.647 N m for the three beams considered, which were very close to the empirical values and consequently validated the model (8.3). 

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Amorphous networks, 4-5 nAmorphous solid synthesis via ultrathin-film multilayer composites analysis of solid-state reaction mechanisms, 357,358/ application to synthesis of metastable ternary compounds, 366 control of crystallization of amorphous aUoy, 360,363,365-367/ control of formation of homogeneous amorphous alloy, 360,361-36 differential scanning calorimetric procedure, 359-360 grazing measurement procedure, 359 lugb-angje XRD procedure, 359 length sddes vs. course of solid-state reactions, 360,361-362/363 quantitative analysis of interdiffiision reaction, 356-357... 

In principle, the as-method is not restricted to nitrogen adsorption and can be applied to any gas-solid physisorption system irrespective of the shape of its isotherm it can be used to check the validity of the BET area and also to identify the individual mechanisms (monolayer-multilayer adsorption, micropore filling or capillary condensation). Numerous examples of different as-plots are to be found in subsequent chapters. Here, we are concerned with the general principles of the as-method of isotherm analysis with particular reference to the evaluation of surface area. The distinctive features of various hypothetical as-plots are revealed in Figure... 

To optimize the mechanical stability of a film deposited on a substrate or of a multilayer system, it is therefore necessary to understand the mechanisms causing bulk and interface damage. An analysis of this kind involves using a series of appropriate and complementary mechanical tests. 

When the pore walls are thin, as is the case here, such a process can be shown to lead to an enhancement of 1(Q). From further quantitative analysis, which will be described subsequently, information on the pore wall structure and the effective thickness of the benzene film in the monolayer/multilayer region can be derived. A schematic mechanism for the progressive uptake of benzene in the organised cylindrical pore structure is illustrated in Figure 5. 

In the polymer industry, packing material, laminates including multilayer films, pellets or molded products can be analyzed by NIR. Even polymer latex particles with up to 99 % water content may be analyzed. NIR provides information about reaction mechanisms, polymerization, crystallinity, orientation, water content and hydrogen bonding, even during the process of polymer manufacture. For example the disappearance of the double bonds in polyethylene and polypropylene can be monitored. In the NIR spectrum C=C bonds lead to a combination band at about 4740 cm and a first overtone at about 6170 cm NIR spectroscopy is applied to characterize ester-, nitrile-, or amide-based acrylic and methacrylic polymers. Other examples are the identification of polyvinylchloride, polyvinyl alcohol and polyvinyl acetates or the analysis of polymerization in epoxy and phenolic resins. 

Once a weave coding is defined, an analysis of the weave matrix allows answering questions about mutual positions of the yams. Consider a warp yam between two intersections with weft. Which weft yams is it interacting with in these intersections What is its position vis-a-vis these yams An answer to these questions is evident for one-layer weave, but for multilayered weaves it needs analysing the weave code. Knowing these answers allows definition of interactions between warp and weft, which is needed for building a geometrical model of the unit cell based on mechanics of these interactions, and definition of contacts between the yam needed for creation of meso-level FE models. 

The analysis so far assumes that there is no adsorption occurring on the pore wall prior to the capillary condensation or after the evaporation. That type of analysis is applicable to systems, such as water adsorption on perfect hydrophobic surface such as that of a graphitized charcoal. In this section, we will deal with the case where we will have adsorption (multilayer adsorption is allowed for) prior to the condensation, and this so-called adsorbed layer will grow with pressure (for example following the BET mechanism). This growth in the adsorbed layer will... 

X-ray diffraction (XRD) is a useful, complementary tool in the structural characterization of porous silicon (pSi), providing information not readily available from direct visualization techniques such as electron microscopies. This review outlines key considerations in the use of diffraction techniques for analyses of this material in both thin film form and freestanding porous Si nano or microparticles. Examples of the range of content in the analysis of pSi are provided, ineluding formation mechanisms, layer thickness, extent of pSi oxidation, and degree of crystallinity. Such properties influence practical properties of pSi such as its biodegradability. We also focus on selected key properties where XRD has been particularly informative (a) strain, (b) the structural analysis of pSi multilayers, and (c) an analysis of pSi loaded with small molecules of fundamental or therapeutic interest. 

Interface stability in co-extrusion has been the subject of extensive analysis. There is an elastic driving force for encapsulation caused by the second normal stress difference (56), but this is probably not an important mechanism in most coprocessing instabilities. Linear growth of interfacial disturbances followed by dramatic breaking wave patterns is observed experimentally. Interfacial instabilities in creeping multilayer flows have been studied for several simple constitutive equations (57-59). Instability modes can be traced to differences in viscosity and normal stresses across the interface, and relative layer thickness is important. 

Included here as examples is a discussion of the characterization of PETA ectra blends, blends prodnced by cryogenic mechanical alloying, various polyurethane polymers, multilayers and structnred spheres, as well as rubber composites. The discussion of the PETA/ectra blends is particularly instructive, as this study combined chemical and orientational analysis. 

Example 1 Kurokawa et al. used SEM and TEM to investigate the mechanism of adhesion between aluminum nitride (AIN) and tungsten (W) electrodes in a multilayer capacitor. Several investigators have reported the absence of a chemical reaction interlayer between W and AIN, but the mechanical strength of the interface is still considerable (>20 MPa). Electron microprobe analysis using an... 

For further information on ceramic actuators, see Uchino (1993). It has been recognized that in modern multilayer piezoelectric actuators (MPAs), the combination of thermal, electrical and mechanical loads during service may affect the functional integrity of the devices. As the details of these effects and their synergistic coupling are still unknown, modeling of the nonlinear behavior of these temperature-sensitive functional properties and their implementation into finite element analysis (FEA) tools has been performed recently (Griinbichler et al., 2008). 

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