Papers by Keyword: Adhesive Property

Abstract: This paper deals with the stress discontinuities in shear stress distribution of adhesive joints. The three-dimensional finite element analysis (FEA) software was used to model the joints and predict the shear stress distribution along the whole beam. The FEA results indicated that there are stress discontinuities existing in the shear stress distribution within adhesive layer and adherends at the lower interface and the upper interface of the boded section. The numerical values of the shear stress concentration at key locations of the joints and the stress concentration ratio are discussed.

Abstract: This paper deals with the stress discontinuities in normal stress distribution of adhesively bonded beams. The 3-D finite element analysis (FEA) software was used to model the beams and predict the normal stress distribution along the whole beam. The FEA results indicated that there are stress discontinuities existing in the normal stress distribution within adhesive layer and adherends at the lower interface and the upper interface of the boded section. The numerical values of the normal stress concentration at key locations of the beams and the stress concentration ratio are discussed.

Abstract: In this paper, the failure modes of the honeycomb sandwich structure under uniaxial compressions after impact (CAI) are analyzed through experiments and Finite Element Method (FEM). Three cases of impact damage location, two cases of impact damage depth and adhesive properties are investigated by the comparisons of corresponding non-destructive structure. Several conclusions are drawn: the failure modes and the initial damage positions obtained from experiments and FEM simulations are almost the same; the location of impact damage may affect the overall loading capabilities of the sandwich structure, whose decreasing rate peaks when the damage is at the top surface and drops when the damage is at the marginal area; different adhesive layer property of interface may lead to the failure mode change, that is, instead of honeycomb core failure, interlaminar failure will occur when the fracture energy of the adhesive layer is low; the damage level and risky location of the structure will vary relevant to the impact energy.

Abstract: In this paper,TiAlN films were deposited on the surface of tool steel substrates using multi-arc ion plating technology at the assistance of hollow cathode（HC）electron beam. The influence of hollow cathode electron beam on the phase composition、microstructure and the performance of TiAlN films were studied.The phase composition，microstructure，surface profile and adhesive strength of the films to the substrate were investigated by X-ray diffraction（XRD）,scanning electron microscopy(SEM),Profilemeter and UNMT-1 Multi-specimen Test System respectively.The results show that with the increase of the current of the hollow cathode, the preferred orientation of（200）was weakened，and the surface of TiAlN films become smooth and the macroparticals decreased obviously.The hollow cathode electron bean can remarkably improve the adhesive property of TiAlN films，and the scratching test show that the critical load from 38N increase to 61N.

Abstract: In this study, the effect of cyanoacrylate-based β-tricalcium phosphate (β-TCP) on pullout strength of orthodontic mini-screw was evaluated. New cements were prepared by mixing Histoacryl® (n-butyl cyanoacrylate) and acid-treated β-tricalcium phosphate. The ratios of β-TCP to Histoacryl® were 0, 0.5, 1.0, and 2.0. Artificial bone blocks were used as a substrate for the miniscrew implantation. The test groups were divided into three groups (one solid bone block [group 1] and a bone block with a 0.9 mm hole [group 2], and a bone block with a 2.5 mm hole [group 3]). And each group was divided into subgroups according to cement usage and non-usage. The used artificial bone density was 0.64g/cm2. Pullout strengths were determined using a universal testing machine. Statistical analysis was performed using the SPSS 9.0 for Windows program. Paired samples t-tests and ANOVA were used with p<0.05. The maximum pullout strengths were 295.9 ± 3.8 N for group 1, 261.1±15.0 N for group 2, and 273.2±20.0 N for group 3. In group 1 and 2, the pullout strength in the subgroup using cement was higher than that of the subgroup of not using cement (p<0.05). In group 3, the pullout strength in the subgroups using cyanoacrylate-based β- TCP cement was higher than that of the subgroup using conventional glass ionomer cement (GC Fuji-I, GC Co., Tokyo, Japan) (p<0.05). These results indicate that our β-TCP/Histoacryl® cements have the potential to enhance pullout strength of the orthodontic mini-screw.

Abstract: Histoacryl® (N-butyl-2-cyanoacrylate) has been widely utilized as a tissue adhesive. The aim of this study was to evaluate the physical and adhesive properties of newly developed cyanoacrylate-based β-TCP composite systems. The β-TCP powder was modified on the surface with citric acid to make this material mixed with cyanoacrylate easily. The setting time of acidtreated β-TCP/ Histoacryl® systems was dramatically prolonged and the polymerization heat was significantly decreased compared to that of untreated β-TCP/Histoacryl® system. The shear bond strength of cyanoacrylate-based β-TCP composites decreased with addition of acid-treated β-TCP filler. The compressive strength of β-TCP/Histoacryl® composites increased strongly with increasing the amount of acid-treated β-TCP filler. The cytotoxicity of the β-TCP/Histoacryl® composites decreased with the increasing of the amount of added β-TCP. These results indicated that our novel β-TCP/Histoacryl® composites had the great potential to serve as adhesives or filling materials in the dental field.

Abstract: Chemical vapor deposit (CVD) diamond coating layer is expected to extend the lifetime of mechanical parts that are used severely abrasive conditions. However, one of the most severe problems is that the delamination between the CVD diamond coating layer and the silicon substrate occurs frequently due to large difference in the material properties. Therefore, the nondestructive evaluation of adhesive property of CVD diamond coating layer is needed. To address such a need, back-scattered Rayleigh surface wave is currently applied. However, the interpretation of the acquired signal is not easy at all. To take care of such a difficulty, we proposed the time trace angular scan (TTAS) plot and the frequency spectrum angular scan (FSAS) plot that can make possible of the systematic interpretation of the back-scattered signals from the diamond coating layer. In this paper, the concept of the TTAS and FSAS plots and the experimental results presented to demonstrate the effectiveness of the proposed approach.

Abstract: The propagation characteristics of the back-reflected Rayleigh surface wave in chemical vapor deposit (CVD) diamond coated specimens were investigated experimentally using the ultrasonic backward radiation measurement. The deliberated delaminations produced between the coating layer and the substrate decreased Rayleigh surface wave velocity. This initial experimental result obtained in the present study demonstrates the high potential of the backward radiated ultrasound as a tool for nondestructive evaluation of very thin CVD diamond coating layer.