Bonded cantilever beam

FIGURE 19. Geometry and finite-element mesh for a bonded cantilever beam. 

FIGURE 20. Variation of shear stress along the length of a bonded cantilever beam. 

One of the most useful geometries of the type discussed above are those based on bonded cantilever beams. For example, the symmetrical double cantilever beam... 

Fig. 2. Illustrations of forces to which adhesive bonds are subjected, (a) A standard lap shear specimen where the black area shows the adhesive. The adherends are usually 25 mm wide and the lap area is 312.5 mm. The arrows show the direction of the normal apphcation of load, (b) A peel test where the loading configuration, shown by the arrows, is for a 180° peel test, (c) A double cantilever beam test specimen used in the evaluation of the resistance to crack propagation of an adhesive. The normal application of load is shown by the arrows. This load is appHed by a tensile testing machine or other...

Substrates. Two commercial aluminium alloys (see Table 1), received as hot-rolled sheets (from ALCAN), were the main body-panel materials used in the current work. The thickness of the sheets varied from 1 to 3 mm for the 5754-0 alloy and from 1 to 2 mm for the 6111-T6 alloy. For the tapered double-cantilever beam (TDCB) tests, where the substrates should remain within the elastic region, a high yield strength alloy, 2014, was used throughout. The specimens were prepared and pre-treated prior to bonding using the procedures proposed by Blackman et. al. [2], The chemical compositions of the alloys employed are given in Table 1. 

The epi-polysilicon functional layer is patterned and then etched by the trench etch process described in Section 5.3.4.2. The trench etching forms cantilever beams that act as comb fingers in the acceleration sensor, as well as the insulating trench required for electrical separation of the epipolysilicon wiring and bond pad structures (Fig. 5.3.11 e). Straight, unnotched sidewalls are strictly required, especially for all design elements that form springs or capacitive comb structures. 

In tape-automated bonding (TAB), the semiconductor die, fabricated with bumped interconnect pads, are positioned in apertures of a polymer-film tape, generally polyimide (Kapton , a registered trademark of DuPont), then gang-bonded to cantilevered beams that are formed by photodelineated metal pads on the tape. The tape (film) has sprocket holes along its sides similar to movie film and, like movie film, is handled on reels in automatic equipment for high-speed assembly. ... 

In this chapter, an overview of performance characterization of FRP-wood bonded interfaces by conventional and fracture mechanics tests [4- 7] is presented. Modified ASTM standard tests (ASTM D2559 and D905) are first used to study the service performance and shear strength of the bond under moisture and/or mechanical loads, and then a contoured or tapered double cantilever beam specimen [8] is used to evaluate the fracture toughness of bonded interfaces under dry and wet conditions and cyclic loading. 

Once the performance of the interface bond was established by the previous delamination (durability) tests, contoured double cantilever beam (CDCB) specimens were designed to conduct mode-I fracture tests. In this study, bilayer CDCB specimens (see Fig. 6) were designed by the Rayleigh-Ritz method [8] and used for fracture toughness tests on bonded FRP wood interfaces under both dry and wet conditions. The critical strain energy release rate, G/c, which is a measure of the fracture toughness, is given as ... 

The FABS, whose working principle was very similar to that of the AFM biosensor, was a cantilever-based immunosensor [7]. However, its configuration was much simpler than that of the AFM. Rather than using a piezoceramic translator to pull on intermolecular bonds, it used magnetic particles, which eliminated the need to manually position a tip and sample next to each other with picometer precision and stability. The cantilever-beam force transducer was the only element of the AFM retained by the FABS. 

FIGURE 27.3. Diagram of an ASTM D3433 double cantilever beam specimen. The load is usually applied by attaching a fixture to holes located near the front of the specimen. In general, the initial portion of the specimen is not bonded in order to provide an initial crack. 

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