Cantilever Arrangement Research Articles

Analysis of a flexural wave due to a laser heating pulse: The two-layer assembly case

In the present study laser ablation of a two-layer assembly with a cantilever arrangement is considered. The recoil pressure generated at the vapour front-workpiece interface is formulated and the resulting pressure force (loading force) is computed. The flexural motion of the workpiece due to the loading force is formulated. The first layer of the workpiece is Inconel 625 with a thickness on the order of 200 μm, which may resemble the HVOF (high-velocity oxygen fuel) coating, while the second layer is 1 mm thick stainless steel plate. The simulations are repeated for four values of the first layer thickness and the relation between the magnitude of the displacement and the first layer thickness is discussed. It is found that the displacement of the workpiece reaches as high as 2 μm in the region close to the free end, while the equivalent stress level is high in the region close to the fixed end. The temporal behaviour of the equivalent stress almost follows the displacement behaviour of the workpiece. As the first layer thickness increases, the displacement reduces. The variation of displacement with the first layer thickness is almost linear and the slope of this variation attains high values for certain time periods in the flexural motion.

Modulus of Elasticity and Moment of Inertia of Grass Hedge Stems

The ability of grass hedges to remain erect where runoff concentrates is critical to their control of ephemeral gully erosion. Hedge resistance to failure depends on the mechanical properties of its stems. We measured moment of inertia (I), modulus of elasticity (E), yield strength (Y), and the bending angle (V) at the elastic limit of stems of switchgrass (Panicum virgatum L.), vetiver (Vetiveria zizaniodes L.), miscanthus (Miscanthus sinensis Cv. gracillimus), and tall fescue (Festuca arundinacae). The stems were sorted into morphological age groups—vegetative, green internode, and woody internode. Moment of inertia was determined from stem geometry and modulus of elasticity from stem deflection from load increments applied in a cantilever arrangement. Yield strength and bending angle were calculated from the displacement of the stem at the last load increment before the elastic limit was exceeded. Grass internodes had I values between 8 and 272 mm4. Their modulii of elasticity were between 2.6 and 8.5 GPa, similar to certain plastics, but their yield strengths of 7 to 30 MPa were generally lower than those of the same plastics. The bending angle at the elastic limit for all grasses was between 2 and 8°.

Preparation and applications of magnetostrictive thin films

Amorphous magnetostrictive films of the binary compound SmxFe1−x as well as of the ternary compound (TbyDy1−y)xFe1−x were prepared by rf or dc magnetron sputtering using either a multitarget arrangement with pure element targets or cast composite-type targets. The magnetostrictive properties of (Tb0.3Dy0.7)0.4Fe0.6 and Sm0.4Fe0.6 films were investigated in relation to their preparation conditions. Depending upon these conditions (especially upon the deposition rate, the bias voltage, and the Ar sputtering pressure) amorphous films with a giant magnetostriction of about 250 ppm (−220 ppm) at 0.1 T and 400 ppm (−300 ppm) at 0.5 T for the TbDyFe (SmFe) and an in-plane magnetic easy axis could be prepared. In view of applications in microsystem technologies (e.g., pumps, valves, positioning elements) these films have been tested in a simple cantilever arrangement and the predicted deflection of a magnetostrictive actuated membrane has been calculated.

PENDULUM TEST FOR EVALUATION OF THE RUPTURE STRENGTH OF SEED PODS

ABSTRACTA small impact pendulum was developed to measure the shatter resistance of seed pods. While clamped by their stems, the pods are hit by the rigid pendulum; the rupture energy is derived from the measured angles of swing. The consistency of the pendulum was confirmed by tests on a sample of fine spring wire. The pendulum was then used in a series of trials on 13 rapeseed varieties and rupture energy results were compared with earlier bending moment and bending energy results obtained from tests using a quasi‐static cantilever arrangement. Rupture energy values were much less variable than bending energy. However, the ranking of varieties by all three strength measures was generally similar.

Dual SAW sensor for the measurement of skin friction on structures exposed to turbulent fluid flow

A dual SAW sensor attached in cantilever fashion to a free-floating membrane flush mounted on a structure exposed to turbulent fluid flow are described. Shear stress on the membrane due to the flow conditions, deforms and bends the cantilever beam. The SAW devices are mounted such that one device is in compression and the other in tension. The cantilever arrangement magnifies the deformation of the SAW sensors by many orders of magnitude relative to the membrane. The SAW devices are attached to oscillator circuits and the change in frequency of the SAW oscillators due to the deformation can be accurately measured. The dual arrangement compensates changes in temperatures, electrical, and mechanical noise and other changes and the difference in frequency measured by a mixer is directly related to the shear stress on the structure. Experiments conducted in a wind tunnel are described. [Work supported by ONR.]

X-ray Diffraction Studies of the Axial Tensile Modulus of Rigid-Rod Polymer Fibers

ABSTRACTWe report the design and use of a device to measure the axial tensile modulus of high modulus fibers by following the change in the meridional X-ray spacings as a function of applied tension. The device, which mounts on a Picker 4-circle automated diffractometer, applies tension to the fiber sample by a cantilever arrangement. Tension is measured by a strain gauge bridge on the cantilever arm. The tension is adjusted and read by the control computer, a VAX 11/730. Measurements made on PBZT and PBO fibers before and after heat treatment are reported. For PBZT fibers (as spun, and heat treated at 525° C and 650° C) with tensile moduli of 186, 283 and 290 GPa, the X-ray determined moduli are 348, 385 and 395 GPa. For PBO fibers (as spun and heat treated at 600° C and 665° C) with tensile moduli of 166, 318 and 290 GPa, the X-ray determined moduli are 387, 477 and 433 GPa. These modulus values are to be compared with theoretical values presented by Wierschke in the previous paper and sonic modulus values discussed by Jiang et al in the following paper.