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To improve the mechanical strength and antifouling properties of poly(ether sulfone) (PES)/sulfonated poly(ether sulfone) (SPES) blend membranes, three kinds of SPES with different molecular weights were attempted as additives. This is the first time that SPES with both high molecular weight (Mw = 141 000 g mol–1) and a high degree of sulfonation (DS, 30%) was used for membrane fabrication. It is also the first investigation of the effect of molecular weight of SPES on the properties of the blend membranes. The results show that the compatibility between PES and SPES was very high. The molecular weight of SPES affected the viscosity of the blend solutions but not the cloud point. The membrane morphology, surface chemical compositions, and mechanical strength were investigated. In addition, the surface hydrophilicity, surface charge, pore structures, and antifouling properties of the fabricated membranes were evaluated. The membrane fabricated with a casting solution containing SPES of high molecular weigh...

In this study, we explain the causes and effects of the geometrical impossible result encountered in the widely adopted tetrakaidecahedron model (Boomsma and Poulikakos, 2001; Dai et al., 2010) for the effective thermal conductivities (ETCs) of metal foam. The geometrical impossible result is successfully eliminated by accounting for the size variation of the node with porosity. The improved model provides predictions of ETCs that are more precise than available models. For aluminum foams (ks=218Wm-1K-1) using water and air as fluid media, the relative root-mean-square (RMS) deviation of the present predictions from the experimental data is about 5.3%; for the reticulated vitreous carbon (RVC) foams (ks=8.5Wm-1K-1), the relative RMS deviation is about 7.4%.

As a result of the trend towards lightweight construction in manufacturing, there has been a significant increase in the use of clinched joints in engineering structures and components. Mechanical structures assembled by clinching are expected to possess a high damping capacity. The aim of this paper is to provide an experimental measurement technique for the investigation of the forced vibration behavior of clinched joints. The dynamic test software and the data acquisition hardware were used in the experimental measurement of the dynamic response of the clinched joints. The frequency response functions of the clinched joints of different clinching point number were measured and compared.

Clinching is a high-speed mechanical fastening technique which is suitable for point joining coated and pre-painted sheet materials. In this study, an experimental measurement technique was provided for the prediction of the free vibration behavior of single-lap cantilevered clinched beams. The dynamic test software and the data acquisition hardware were used in the experimental measurement of the dynamic response of the single-lap cantilevered clinched beams. The frequency response functions of the clinched beams of different clinching number were measured and compared. The main goal of the paper is to provide a basis for further research on vibration based non-destructive damage detection in clinched beams.

Clinching is a cold forming process for hard-to-weld materials joining in the field of automobile lightweight design and manufacture. The automatic crack detection for clinch joints in the loading test is an important monitor process. In this paper, the method of automatic crack detection on clinch joints by using digital image analysis technology was presented, and an image acquisition and processing platform coupled with a single shear pulling test machine was introduced. In order to insure the real-time of the calculation, multiple scan lines perpendicular to the potential crack strip was set, and threshold segmentation and edge detection with Sobel operator was used in the analysis. Results showed that the analysis procedure proposed in this paper is available for automatic crack detection for the loading of clinch joints and can get high computer speed.

The purpose of this study is to propose the analytical model for clinched joint, which can be used to predict the joint strength based on the neck-thickness and undercut of clinched joint. The analytical model has been defined as a function of neck-thickness and undercut based on the neck fracture mode which is the most reasonable and common failure mode for clinched joints. Clinching joining experiment with different joint geometric variables with RIVCLINCH 1106 P50 and tensile-shear test with MTS landmark were conducted. The comparison of the clinched joint strength between experiment and analytical model shows good similarity within 7.2% error. The analytical model proposed for clinched joint strength is valid to calculate the clinched joint strength.

The clinch joining is a new technique to join light alloy materials. This paper studies the process of clinching in joining Copper alloy sheets based on the method of numerical simulation combined with experiment. The studies are performed by employing software ansys/ls-dyna considering with the contact conditions and material models in the model. Efficient analytic results of forming of clinching in Copper alloy sheets are provided. The experiments of clinched joints in Copper alloy sheets are carried out to validate the simulation. It is shown that the simulation of process of clinching joints in Copper alloy sheet has a good agreement with the experimental result. That suggests the developed finite element model, considering the contact conditions of materials and the material models can be used to predict the joint forming of Copper alloy by clinching ideally.

Self-Pierce Riveting (SPR) is a new cold-press rivet technique for hard-to-weld materials joining in the field of automobile lightweight design and manufacture. The interlock slid under mechanical loading was the main induction factor to the failure of SPR joints. In this paper, the property of the interlock slid in SPR joints was studied by using digital image analysis technology and mechanical experiments. A special double-rivets specimen was designed, and simple tensile test was carried out. Several digital microscopes pointing to the region of the mechanical interlock were set up to observe and record synchronously the sequential images of the deformation of SPR during the tensile test. The process of image gray matching for the calculation of the interlock slid was described. Results showed that this method can be used to detect automatically the sliding in SPR joints and analyze the sliding qualitatively and quantitatively. And it can provide a new path for the mechanical property evaluation for this type joints.

A nucleophilic substitution reaction was developed to synthesize the zwitterionic surfactant using a renewable natural fatty acid rather than a petroleum derivative as the raw material. The kinetics and mechanism of the nucleophilic substitution reaction of trimethylamine α-chlorododecyl carboxylate with trimethylamine were investigated in protic and dipolar aprotic solvents including water, ethanol and N, N-dimethyl formamide. The rate equations were derived using initial rates and the activation parameters in different solvents were determined empirically and compared with each other to obtain important information about the reaction mechanism. The overall second-order reaction number and the negative activation entropy supported a bimolecular nucleophilic substitution (SN2) mechanism, combined with the pseudo-first-order kinetics for each reactant. The experimental results also showed that the reaction reactivity diminishes with the decrease in polarity of protic solvents. The typical dipolar aprotic solvent dimethyl formamide distinctively promoted the reaction in. This fact was successfully explained by the solvation rule for SN2 reactions.