Flutter of Thermally Buckled Composite Sandwich Plates

A high precision high order triangular plate element is developed for the linear flutter analysis of thermally buckled composite sandwich plates. Due to uneven thermal expansion in the two local material directions, the buckling mode of the plate may be shifted from one pattern to another for certain fiber orientation or plate aspect ratio as the aerodynamic pressure is present. This buckle pattern change alters the frequencies and modes of the plate and that in turn changes the flutter coalescent modes. Numerical results show that temperature has a destabilizing effect on the flutter boundary but the aerodynamic pressure has a stabilizing effect on the buckling boundary.     

Surface and subsurface damages and magnetic recording pattern degradation induced by indentation and scratching

Magnetic recording pattern degradation due to head–disk impact and scratching are simulated by static indentation and scratch testing, respectively, on a pre-recorded thin film magnetic recording disk. Different magnitude of controlled stresses were used to induce stress and physical damage to the magnetic recording disk resulting in erasure and distortion of the magnetic recording pattern. Both nanoindentation and scratching resulted in the elastic–plastic deformation of the multilayer coating of the magnetic recording disk but in different relative magnitude and types of in-plane stresses (which are effective in causing magnetization changes). For residual indentation and scratch depths of the order of the magnetic disk coating thickness, magnetization changes in the recording pattern were observed even though the protective carbon overcoat was not damaged. Large magnetic pattern distortion and erasure results where cracks and pileups, and delamination and buckling damages were observed for deeper indentation marks and scratch grooves, respectively.     

Planning and assessment system for light rail transit construction in Taiwan

Microsystem Technologies - The development of public transportation systems is emphasized worldwide. Energy conservation and carbon reduction are necessary and constitute a constraint for the...     

Isolation and characterization of acid and pepsin-solubilized collagens from the skin of balloon fish (Diodon holocanthus)

Acid-solubilized collagen (ASC) and pepsin-solubilized collagen (PSC) were successfully extracted from the skin of balloon fish (Diodon holocanthus) with yields of 4% and 19.5% respectively (based on dry weight). According to the electrophoretic patterns, both the ASC and PSC consisted of two different α chains (α1 and α2), were characterized to be type I, and contained imino acid of 179 and 175 residues/1000 residues, respectively. The PSC had a lower content of high-molecular weight cross-links than the ASC. The ultraviolet (UV) absorption spectrum of collagens showed that the distinct absorption was between 210 and 230 nm. A maximum solubility in 0.5 M acetic acid was observed at pH 1–5, and a sharp decrease in solubility above 4% (w/v) in both the ASC and PSC was observed in the presence of NaCl. The denaturation temperatures (T_d) of the ASC and PSC measured by viscometry were 29.01 °C and 30.01 °C, respectively. The maximum temperatures (T_max) of the ASC and PSC were 29.64 °C and 30.30 °C, respectively.     

Aerothermoelastic analysis of composite laminated plates

The flutter behavior of a thermally buckled composite laminated plate is investigated in the frequency and time domains using the finite element method. Von Karman large deformation assumptions and quasi-steady aerodynamic theory are employed for the analysis. The effects of temperature gradient, panel length-to-width ratio, fiber orientation, and stacking sequence on aerothermoelastic behavior of the plate are studied in detail. The flutter boundary, buckling boundary, time history response, and phase plane plots of cross-ply and angle-ply laminates are presented. The numerical results show that temperature gradient induces thermal moments and increases the overall stiffness of the plate, and thus may increase the flutter boundary significantly. When the buckle pattern of the plate changes, the eigenvalues of the natural modes are changed suddenly and the sequence of the natural modes may be altered. Therefore, the change in the buckle pattern postpones the coalescence and the flutter boundary may increase. The change in the coalescence pair may also postpone the coalescence and increase the flutter boundary.     

The effect of dynamic behavior on surface roughness of ball screw under the grinding force

The dynamic behavior of a ball screw under a moving grinding force and the resulting ball screw surface roughness are investigated. The system includes a ball screw, a headstock, a tailstock, a steady rest, a grinding wheel, and a wheel head. Equations of motion of the system are derived through Lagrangian approach combined with global assumed mode method in this study. The transient responses of the system due to a moving force are evaluated using Runge?CKutta method. Results show that the steady rest can reduce 90% vibration in a grinding process. An equation is proposed to predict the maximum response by the cutting depth. Then we simulate the grain height distribution on the grinding wheel, considering transient response on the ball screw and the grinding wheel. Lastly, the ball screw surface roughness could be simulated via calculating the depth of all working grains. The purpose of using grinding process is that the ball screw needs fine surface roughness. The ball screw surface roughness is influenced by the grain size more than the structure numbers can be.     

Transport and deposition kinetics of polymer‐coated multiwalled carbon nanotubes in packed beds

In this study, a modified filtration equation that accounts for the transport and kinetics of polymer‐coated multiwalled carbon nanotubes in columns packed with crushed Berea sandstone is presented. The columns were saturated with brine solution, in which the salt concentration was varied from 0 to 10 wt%. Experimental results show that the polymer effectively eliminates the effects of salt on particle deposition when the salt concentration is less than or equal to 10 wt%. The calculated cumulative particle recovery is as high as 88.47 ± 0.25%. Results show that, at 10 wt% salt concentration, the proposed equation successfully predicts the experimental behavior, especially at the early stages of the breakthrough, where commonly used models fail. It is argued that the new equation accounts for the dynamic change of single collector efficiency as the deposition process advances. When tested against prior results available in the literature, the proposed model agrees with published data from other investigators. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3774–3783, 2016     

FOUR-PHASE MODEL FOR FLUIDIZED-BED CATALYTIC REACTORS

A four-phase model for fluidized-bed catalytic reactors is developed. The bed is divided into four phases, i.e., bubble, cloud-wake, emulsion upflow, and emulsion downflow phases. In the model, gas back mixing in the emulsion phase and gas interchange as well as gas cross flow between phases are all considered. Model predictions are shown to compare well with various published experimental data on both axial concentration profiles and overall conversions. Parameters effects on the reaction performance were also illustrated. It was found that neglecting cross flow will result in 13% lower on the predicted conversion.     

Selective extraction of metal ions through liquid surfactant membranes

Selective separation of metal ion from a liquid solution with the help of different permeation rate of solutes through liquid membranes was performed. The salts used were ZnCl₂, CdCl₂, NiCl₂. D2EHPA and LIX64N were used as carrier to study the extraction rate of the solutes. The results show that at low pH value of external phase the order of degree of extraction by D2EHPA or LIX64N is Zn > Cd > Ni, while at high pH value with the presence of ammonia in the feed solution the order of degree of extraction is reversed to Ni > Cd > Zn. The results also indicate that when the mixed carrier is used an enhanced effect on the extraction was observed. Synergistic effect was also noted when comparing the cases with mixed carriers to those with pure carriers.