Free vibration analysis of an adhesively bonded functionally graded double containment cantilever joint

In this study, Genetic Algorithms (GAs) combined with the proposed neural networks were implemented to the free vibration analysis of an adhesively bonded double containment cantilever joint with a functionally graded plate. The proposed neural networks were trained and tested based on a limited number of data including the natural frequencies and modal strain energies calculated using the finite element method. GA evaluates a value generated iteratively by an objective function and this value is calculated by the finite element method. The iteration process restricts us apparently to use directly the finite element method in our multi-objective optimisation problem in which the natural frequency is maximised and the corresponding modal strain energy is minimised. The proposed neural networks were used accurately to predict the natural frequencies and modal strain energies instead of calculating directly them by using the finite element method. Consequently, the computation time and efforts were reduced considerably. The adhesive joint was observed to tend vertical bending modes and torsional modes. Therefore, the multi-objective optimisation problem was limited to only the first mode which appeared as a bending mode. The effects of the geometrical dimensions and the material composition variation through the plate thickness were investigated. As the material composition of the horizontal plate becomes ceramic rich, both natural frequency and modal strain energy of the adhesive joint increased regularly. The plate length and plate thickness were more effective geometrical design parameters whereas the support length and thickness were less effective. However, the adhesive thickness had a small effect on the optimal design of the adhesive joint as far as the natural frequencies and modal strain energies are concerned. The distributions of optimal solutions were also presented for the adhesive joints with fundamental joint lengths and material compositions in reference to their natural frequencies and corresponding modal strain energies.     

Effect of different dentin adhesives and application modes on sealing ability of amalgam restorations

Purpose: The aim of the study was to evaluate the sealing ability of bonded amalgam restorations using different adhesive materials with different adhesive application methods including amalgam bonding application. Materials and methods: The prepared Class-V cavities were randomly assigned to four application groups of four tested dual-curing dentin adhesives (Scotchbond Multi-Purpose Plus, XP Bond, Xeno IV and Clearfil Liner Bond 2V), dual-curing resin-based cement (Panavia F2.0) and a control group (unlined amalgam). Group 1 adhesives were applied according to the instructions for direct light-curing, Group 2 chemical-curing mode was applied according to the manufacturer’s amalgam bonding instructions. Group 3 adhesives were first applied in light-curing mode, and then amalgam bonding adhesive was applied. Group 4 adhesives were first applied in chemical-curing mode, followed immediately by light-curing mode. After that, amalgam adhesive parts were applied; then, the amalgam was condensed and carved. After storage for 24 h in distilled water at 37 °C, restorations were finished and polished. The teeth were then thermocycled (500 cycles between 5 and 55 °C), and the specimens were examined for microleakage using methylene blue as a marker. Results: Compared to the control group, the adhesive application modes significantly reduced microleakage for both dentin and enamel margins (p < 0.05). In dentin margins of the adhesives tested, Group 4 showed the lowest leakage score. On the enamel margins for Scotchbond Multi-Purpose Plus and XP Bond, Group 1 showed the highest microleakage (p < 0.05). Conclusion: According to marginal sealing ability and ease of application, Group 2 was recommended for the etch and rinse systems, and Group 4 was also recommended for the self-etch systems under amalgam restorations.     

Nonlinear stress analysis in adhesively bonded single-lap joint

In this investigation, an analytical elastic–plastic solution was proposed for a single-lap joint. A ductile adhesive joint material was used as the bond material. FM-73 was utilized in the study. The influence of the bending moment was neglected in the solution. The solution was modified for shear stresses. The analytical solution was compared with the FEM solution. An ANSYS 10.0 solution was employed in the numerical solution. Both solutions were compared with each other. These two solutions produced close agreements.     

The influence of retention hole and adhesive systems on the shear bond strengths of resin composite to amalgam

The aim of the study is to evaluate the influence of surface-treatment methods with and without the use of a retention hole on the shear bond strength of a resin composite adhered to amalgam using an adhesive system. Amalgam specimens were divided into six groups. Group 1 (Bur) specimens were roughened with a diamond bur, Group 2 (Al₂O₃) specimens were sandblasted with a 50?μm aluminum oxide powder, Group 3 (CoJet^®) specimens were sandblasted with 30?μm CoJet^® Sand, Group 4 (Bur?+?Rh) specimen surfaces were prepared with a retention hole 1?mm in diameter and 1?mm deep and roughened with a diamond bur, Group 5 (Al₂O₃?+?Rh) specimens were also prepared with a retention hole and sandblasted with 50?μm aluminum oxide powder, and Group 6 (CoJet^®?+?Rh) surfaces were prepared with a retention hole and sandblasted with 30?μm CoJet^® Sand. Resin composite cylinders were bonded onto the amalgam surfaces using Xeno^® IV, Optibond? All-In-One, Clearfil? SE Bond, Adper? Single Bond Plus, and Scotchbond? Multi-Purpose adhesive systems. In addition, silane (Monobond S) was used for Groups 5 and 6. The shear bond was determined and statistically analyzed using two-way analysis of variance and post hoc Tukey’s tests (p?≤?0.05). The surface treatment significantly affected the shear bond strengths of the adhesive systems. The shear bond strengths of Optibond? All-In-One (2.661?±?0.48?MPa) in Group 1 and Scotchbond Multi-Purpose (3.818?±?0.98) in Group 4 were significantly higher than those of the other adhesive systems. Silica coating of the amalgam surface significantly improved the shear bond strength of the resin composites. The addition of a retention hole on the amalgam affects the bonding strength of the composite adhesion.     

Control and dynamic analysis of a packed distillation column based on modeling approaches

In this work, dynamic analysis and control of a packed distillation column have been utilized theoretically and experimentally. In theoretical studies, two types of mathematical models stagewise (Frank model) and partial differential approaches (back-mixing model), were used. Packed distillation uses 1400 mm packing height, and packing type is rashing ring with 20-15 mm diameter. The reboiler was made from a 13 L glass container. Reflux ratio was adjusted by an on-line computer. The system temperature was measured with six thermocouples. For control studies, the reflux ratio and the reboiler heat dutywere chosen as manipulated variables. Perturbation in feed composition was utilized as the disturbance. Decoupling multivariable dynamic matrix control (DDMC) and Nondecoupling multivariable dynamic matrix control (NDMC) of overhead and bottom compositions were applied for control studies. Performance of the control system was tested by using an integral absolute error (IAE) criterion and it was also compared with decoupling multivariable PID control (DPID) and Nondecoupling multivariable PID control (NDPID).     

Effects of Different Denture Cleansers on the Tensile Bond Strength of Denture Liners

The effect of two denture cleansers (Polident® and Protefix®) on the tensile bond strength between four soft liner materials (Molloplast B®, Permaflex®, Sofreliner Tough Medium®, and GC Reline Soft®) and a conventional denture base resin was investigated. For each of the liner materials 35 test specimens were prepared according to test the requirements and assigned into seven groups (n = 5). Before tensile testing, five of the liner specimens were kept in water or soaked in two cleansing solutions during 2 and 7 d. Five other samples served as a control group subjected directly to tensile testing. The bond strength values were obtained using a universal testing machine and compared statistically. The type of failure was assessed visually. No significant difference was found between the groups for the tested conditions used (p > 0.05). The most frequent failure mode was cohesive for Molloplast and Permaflex specimens, adhesive for Sofreliner Tough Medium, and a mixed type of failure was observed for GC Reline Soft material.     

Bake-Hardening Response of High Martensite Dual-Phase Steel with Different Morphologies and Volume Fractions

Bake-hardening behaviour of carbon steel with different martensite morphologies and volume fraction was investigated.The specimens with fibrous and bulky martensite were prestrained in tension by 4%.After this,they were unloaded and bake hardened at 180 °C for 10–160 min.It was found that dual-phase steel samples which were bake hardened at 180 °C for 20 min showed an increase in the yield stress(YS) and ultimate tensile stress(UTS) but a decrease in ductility.Further increase in the bake-hardening time of 80 or 160 min has reduced the YS and UTS,but increased the ductility.Dr(increase in stress due to bake hardening),YS and UTS values are higher for the microstructure containing fibrous martensite compared to the microstructure-containing bulky martensite.It was also observed that at a given baking temperature Dr,YS and UTS increased by volume of martensite.     

Fitting Fick’s model to analyze water diffusion into chickpeas during soaking with ultrasound treatment

Fick’s model together with Arrhenius relationship were successfully used to evaluate water absorption of chickpea during soaking at a temperature range of 20-97 °C with 25 kHz 100 W, 40 kHz 100 W and 25 kHz 300 W ultrasound treatments. Use of ultrasound, increase in ultrasound power and soaking temperature significantly (P < 0.05) increased the water diffusion coefficient (D_eff) of chickpea during soaking. Average gelatinization temperature of chickpea was found as 61.47 °C. Activation energy (E_a) values of chickpea for below and above gelatinization temperature were found to be 28.69 and 9.34 kJ mol⁻¹, respectively. Ultrasound treatments significantly decreased the soaking time of chickpea.     

Improvement of the electrochemical hydrogen storage performance of Mg2Ni by the partial replacements of Mg by Al, Ti and Zr

Mg₂Ni, Mg_1.5Al_0.5Ni, Mg_1.5Zr_0.5Ni, Mg_1.5Ti_0.5Ni, Mg_1.5Zr_0.25Al_0.25Ni, Mg_1.5Zr_0.25Ti_0.25Ni and Mg_1.5Ti_0.25Al_0.25Ni alloys were synthesized by mechanical alloying and their electrochemical hydrogen storage characteristics were investigated. X-ray diffraction studies showed that while Al was retarding, Zr and Ti were facilitating the amorphization of Mg₂Ni phase. The initial discharge capacities of Mg_1.5Ti_0.5Ni, Mg_1.5Zr_0.5Ni and Mg_1.5Al_0.5Ni alloys were 414, 322 and 166 mA h g⁻¹, respectively. Although Mg_1.5Al_0.5Ni alloy had very low initial discharge capacity, the capacity retaining rate of this alloy was much better than those of Ti- and Zr-including alloys. The potentiodyanamic polarization experiments in 6 M KOH solution presented that Mg was passive and Ni was immune in the charge/discharge potential range (−1.0 V_Hg/HgO and −0.5 V_Hg/HgO). At the same conditions Ti and Zr had moderate, and Al had extremely higher dissolution rates. The analysis by the electrochemical impedance spectroscopy revealed that the increase in the charge transfer resistance of Mg_1.5Al_0.5Ni alloy was relatively low with the increase in depth of discharge. This observation was attributed to the formation of the porous unstable Mg(OH)₂ layer due to the high rate dissolution of the disseminated Al₂O₃ and thus the exposition of the underlying electro-catalytically active Ni sites. The charge transfer resistance of Mg_1.5Ti_0.5Ni alloy increased sharply with the increase in depth of discharge possibly due to the stabilizing effect of Ti-oxide on Mg(OH)₂. The presence of Ti-oxide, however, was predicted to make Mg(OH)₂ barrier layer more penetrable by hydrogen atoms, since the increased stability of the surface layer the cyclic stability of Mg_1.5Ti_0.5Ni alloy was relatively satisfactory.