Vermiculite Starch-based Nanocomposites and Applications

Evaluation of thermal aging activation energies based on multi-scale mechanical property tests for an austenitic stainless steel weld beads

Acrylic bone cements: mechanical and physical properties

The recent development of electronic materials that can maintain electrical performance while undergoing large applied strains have demonstrated potential for use in a new breed of electronic systems. The rapid development of these electronic systems that are flexible, stretchable, and/or wearable necessitates the concurrent development of robust mechanical and electrical test methods to improve their design and reliability. In this paper, one such mechanical test method is discussed in which a stretchable electronic test coupon is mounted onto an inflatable bladder of known geometry to induce multiaxial strains, while in-situ 4-point resistance measurement is employed to assess the device's performance and electromechanical integrity. The material combination of a stretchable screen-printed silver ink cured onto a thermoplastic polyurethane (TPU) substrate is studied given the proclivity for the use of TPU in wearable devices. A dome-shaped bladder configuration is employed in this work to study the performance of printed conductors under biaxial stretching. Various monotonic and cyclic loading regimes are employed to characterize the fatigue behavior and maximum use conditions of the samples. Volume of water displaced into the bladder during inflation is measured and correlated to the induced multiaxial strains on the mounted devices using 3D digital image correlation. Relationships between resistance and applied multiaxial strains are presented. Experimental results are compared with literature, and plausible extensions of the test method including direct printing on the bladder material are discussed.

Elastic index is the required important parameters in the theoretical analysis and design calculation of components. Mechanical testing method and electrical measuring method are commonly used in mechanics experimental. This article discusses the ultrasonic method which is used to measure the material elastic index. In this paper, Using ultrasound method to measure the elastic index of 1095 steel, and comparing with literature values, ultrasound measurement method and electrical measurement method are used to measure modulus of elasticity of Mullite ceramic. Experimental results show that the ultrasonic measured elasticity coefficient value is very similar with literature value; Comparing the two groups of experimental data,it is found that data obtained by ultrasound measurement method is compact while data obtained by electrical measurement method is dispersed and the average value of two groups variate within 5%. This method has benefits such as no use of strain gauge,low costs, short cycle and multi-point measurement, thus it is suitable for multi-person experiment. In addition, this method can broaden students’ knowledge horizon and cultivate independent thinking ability and practical ability. Introduction Elasticity indicators Including the young's modulus of elasticity, poisson's ratio, shear modulus of elasticity are the important need parameters in process of theoretical analysis and design calculation. In the present course of engineering mechanics, the elastic index of the material is mainly determined by mechanical testing method or electrical measuring method[1,2]. But mechanical testing method is big costs due to use a specimen for measure once. Electrical measuring method requires students to accept training and test cycle is long, so the demand to the student ability is high. In this paper, ultrasonic method was used to measure the material elastic index. The method by measuring the density of material, the material of transverse wave and longitudinal wave propagation velocity, is used to calculate the material elastic performance indicators such as shear modulus, young's modulus of elasticity and poisson's ratio, etc. This method broadens students’ knowledge horizon and improves students’ experiment analytical abilities, being suited for promotion in college mechanical curriculum with fewer classes and more students participate in experiments.

Infiltrated moisture combined with repeated action of traffic and environmental loading generates distresses which adversely affect the durability of asphalt pavements. Almost 94% of states' highway agencies use either the Loaded Wheel Tracking (LWT) test or the Modified Lottman test to capture asphalt mixtures' moisture susceptibility. However, the current LWT and the modified Lottman test practice lack accuracy in relating laboratory performance to observed field performance. The study's primary objective was to evaluate the capability of different laboratory mechanical test methods to predict moisture susceptibility of asphalt mixtures. Asphalt binder and mixture experiments were conducted to achieve the objective of the study. The study utilized two asphalt binder types (PG 67-22 and PG 70-22) along with three aggregates (limestone, crushed gravel, and semi-crushed gravel). Both the asphalt binder and asphalt mixture experiments included five levels of moisture conditioning; 1) short-term aging (control); 2) single freeze-thaw (FT-1); 3) triple freeze-thaw (FT-3); 4) MiST 3500; and 5) MiST 7000. The asphalt binder experiment included rheological characterization of conditioned asphalt binder using Frequency Sweep test and MSCR test. Seven 12.5mm NMAS asphalt mixtures were employed in the asphalt mixture experiment. A suite of mechanical test methods, including the LWT, the modified Lottman, and the SCB test, was conducted on moisture conditioned asphalt mixtures. Freeze-thaw and MiST conditioning resulted in a stiffer asphalt binder when compared to the control. The LWT and the SCB test exhibited an increase in moisture damage associated with progressive freeze-thaw and MiST conditioning of asphalt mixtures. In contrast, the modified Lottman test showed consistent test results only with freeze-thaw conditioning. Observing moisture damage caused by conditioning levels made it possible to predict moisture susceptibility of the asphalt mixture. Employed mechanical test methods reported an increase in moisture resistance of asphalt mixtures with either SBS modified asphalt binder or with anti-strip asphalt binder when compared to conventional asphalt binder. Furthermore, the SCB test and the LWT test results showed a similar trend in predicting the aggregate type's effect on the asphalt mixture's moisture susceptibility. The SCB test exhibited the potential to capture moisture damage in asphalt mixtures. To standardize the SCB test as a moisture damage test, a thorough investigation to relate laboratory performance to observed field performance should be done

Mechanical testing methods were developed by us using the pulsatile internal pressure through-flow system. The methods were applied to estimate the permeability and fatigue strength of a vascular substitute, the mechanical behaviour of anastomosed site between vascular substitute and blood vessel, and the mechanical behaviour of the blood vessel itself. A testing method is also proposed for puncturing a vascular substitute which is used as blood access for hemodialysis. The mechanical behaviour of punctured vascular substitute and the puncturing technique itself are investigated. The fatigue-creep testing method of cellophane membrane is also reported to estimate the durability of cellophane membrane by using the circulating pulsatile internal pressure through-flow system. The mechanical testing method for visco-elastic characteristic of biomaterials is discussed.

Corresponding experiments were designed and accomplished to obtain the authentic mechanical response mechanism of pavement under different loading conditions. Replicability and reproducibility of the experiments were discussed in this paper. Meanwhile, the response mechanism for three typical pavement structures was analyzed. Results show that mechanical response test method for pavement structure has characteristics of good replicability, reproducibility, and reliability. The method can also be used as an effective way to investigate the mechanical response of pavement structures. The mechanical states of different pavement materials under the same test condition are quite different. For cement bound granular and asphalt concrete, radial strain changes as alternative compression-tension with obvious mechanical response characteristic. However, the situation is different for cement concrete. The region of pavement that is close to the surface is in compressive state. By contrast, the far region is in tensile state. Top-down cracking of pavement developed from top surface crack may appear when load is too heavy. The working state of pavement can be reflected by utilizing the mechanical response test method. The mechanical response test method is a good reference when calculating mechanical state and determining parameters of pavement material.

The hardness of cooked rice is one of the most important criteria which determine the rice quality. The commonly used near-infrared reflectance (NIR) method is still in argument due to its indirectness and possible error. In this paper, a mechanical method was proposed and its principle, automation, components and operative reliability were evaluated and compared with the NIR method. The results showed that the mechanical testing method can accurately detect the rice quality and were consistent with the NIR testing data. This new mechanical method can be effectively used in rice quality testing and branding with the advantage of simplicity, accuracy and reliability.

This study focusses on the bond between asphalt and concrete. The bond is a decisive factor for the transfer of traffic loads. A lack of bond between the layers can quickly reduce the load-bearing behavior and thus lead to pavement failure. In the literature, the bond between asphalt pavements and concrete substrates is usually analyzed using mechanical test methods. With mechanical test methods, the effects of interlocking, glue adhesion and friction, which have an effect at the layer boundary, are not considered individually. Based on previous findings, the aim of this study is to carry out a precise analysis of the bonding at the layer interface between concrete and asphalt using bitumen emulsion by means of measurements with a high-resolution X-ray computer tomography (CT). To determine the effect of the surface texture of the substrate, the investigations were carried out on milled and smooth surface textures. In addition to the variation of the substrate profiles, the influence of the application quantity of the bitumen emulsions C40 B5-S and C60 BP4-S was analyzed by spraying quantities of 90 g/m² and 180 g/m² bitumen after breaking. A newly developed method was used to determine the effective degree of gluing at the layer boundary, which allowed the bonding efficiency to be determined. The results of the calculated degree of gluing for the individual variants show that the highest degree of gluing of 61.94% is achieved with the smooth texture variant and high application quantity of bitumen emulsion. The lowest degree of gluing of 17.01% was achieved with the milled texture variant without the application of bitumen emulsion. Overall, the results showed that the degree of gluing was increased for both surface textures by applying the bitumen emulsion. Compared to the smooth texture, the milled textures exhibit a lower degree of gluing for both bitumen quantities, which could be explained by the distribution of the bitumen emulsions on the substrate profiles.

Discussion on the evaluation and standardization of test methods to obtain the material properties of continuous fiber sheets, which is applied to the repair and strengthening of concrete structures, have been conducted from 1998 in a working party of a research committee in the Japan Society of Civil Engineers. Among the mechanical and durability test methods to be standardized, the current discussions on the tension and bond test methods are introduced in this paper. As for the tension test, a new method to make the specimen to cope with large-tow or thick-yarn continuous fiber sheet is proposed and is to be adopted as one of the standard speciments. The variation of strengths depending on the different test specimens is discussed based on test results and a numerical analysis. As for the bond test, many elaborate test methods have been proposed but the simplicity is regarded very important for design application. Then a simple test method is proposed as the standard method and a simplified evaluation method on bond strength is introduced.

Every new development in device performance and packaging design, can drastically affect the reliability of devices due to implementation of new materials and design changes. High performance and high reliability demands in power electronics over several decades and a short time to market development, raise the need for very fast reliability testing methods. In this study a mechanical fatigue testing method is presented for evaluating the interfacial fatigue resistance of heavy Al wire bonded interconnects in high power modules. By separating the concurrent thermal, mechanical and environmental failure mechanisms a selective investigation of the desired failure mode is possible. The setup is designed to reproduce the thermo-mechanical shear stresses by mechanical means, while provoking the same lift-off failure mode as in power cycling tests. With a frequency variable test setup of a few Hz up to several kHz, measurements from 103up to 108loading cycles and determining the influence of the testing frequency on the fatigue life are possible. A semi-automated bond wire fatigue tester operating at 60 kHz is presented which is suitable for rapid screening and qualification of a variety of wire bonds at the stages of development and during the production.

Commercial exploitation of marine natural gas hydrate (NGH) is crucial for energy decarbonization. However, hydrate production would weaken reservoir mechanical properties and trigger geohazards. Experimental instruments are the basis to obtain the mechanical responses of hydrate-bearing sediments (HBS). Considering the reservoir deformation processes from elastic deformation to residual deformation during hydrate exploitation, this study comprehensively reviewed the feasibility and mechanical research progress of the bender element, resonance column, atomic force microscope, triaxial shear, direct shear, ring shear, and static penetration in mechanical testing. Each test method’s precision and sample size were comprehensively compared and analyzed. Finally, the limitations and challenges of the current mechanical testing methods for HBS were discussed, and their future development directions were proposed. The proposed development direction in mechanical testing methods is expected to provide insightful guidance for the development of instruments and improve the understanding of the mechanical behavior of HBS.

Chapter 1 Ceramic Matrix Composites—Mechanical Properties and Test Methods Carl Zweben, Carl Zweben General Electric Space Systems Div. P.O. Box 8555, Philadelphia, PA 19101Search for more papers by this author Carl Zweben, Carl Zweben General Electric Space Systems Div. P.O. Box 8555, Philadelphia, PA 19101Search for more papers by this author Book Editor(s):William Smothers, William SmothersSearch for more papers by this author First published: 01 January 1985 https://doi.org/10.1002/9780470320280.ch1Citations: 6Book Series:Ceramic Engineering and Science Proceedings AboutPDFPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShareShare a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Proceedings of the 9th Annual Conference on Composites and Advanced Ceramic Materials: Ceramic Engineering and Science Proceedings, Volume 6 RelatedInformation

Ultrasonic testing is a non-destructive testing method of choice for estimating the anisotropic elastic properties of wood materials. This method is reliable for estimating the Young’s and shear moduli. However, its applicability to Poisson’s ratios remains uncertain. On the other hand, despite their destructive nature, mechanical tests allow a direct measurement of all elastic properties including the Poisson’s ratios. In some cases (e.g. when assessing cultural heritage objects), destructive testing may not be an option. In this work, two types of hardwood walnut (Juglans regia L.) and cherry (Prunus avium L.), which often appear on cultural heritage objects, were tested using both ultrasonic and mechanical testing methods under four different moisture conditions below fibre saturation point. The results show that a higher moisture condition leads to a decrease in material elasticity. For walnut wood, their longitudinal Young’s modulus (\(E_{\rm L}\)) was reduced by 679 MPa under the compression load for a one per cent increase in moisture content. Moreover, three ultrasound data evaluation techniques, which differ in the way they incorporate the Poisson’s ratios (full stiffness inversion, simplified uncorrected, and simplified corrected), were used to estimate the Young’s moduli (E). The main goal is to obtain reliable material parameters using the ultrasound test. As a result, it is concluded that the chosen data evaluation method influences the accuracy of the calculated E. In a certain case, the simplified-corrected method, which requires only one specimen type, gave a closer agreement to mechanical tests (e.g. \(\Delta E_{\rm T}=6\,\%\) deviation on mechanical results). In another case, the full-stiffness-inversion method, which requires four specimen types, gave the best estimation (e.g. \(\Delta E_{\rm L}=2\,\%\)). In this corresponding direction, the simplified-corrected method can only partially reduce the overestimation of the simplified uncorrected from \(\Delta E_{\rm L}=47\) to 32 %. The variation of E produced by different evaluation procedures is due to the different correction factor values, which is a consequence of the variation in \(\nu\).

Mechanical properties of MEMS materials are crucial for MEMS performance and reliability. Micro scale mechanical test has been challenging to MEMS community, due to the difficulties in handling micro scale specimens. In this article, a novel micro mechanical tensile testing method has been developed in combining a stiff microscale specimen developed with MTS Tytron Micro Force Tester. The advantages of this method include that it is a standard direct test of micro machined specimens, simple boundary conditions, and easy specimen handling/mounting in characterization. A novel specimen with micro features has been designed and fabricated for the direct mechanical testing. The specimen consists of three micro beams in parallel. The width of the center beam is 40 μm and the outer two beams’ width is 90 μm. The length of all three beams is 4 mm long. An optimized design has been achieved with finite element analysis, which shows that 98% of the total deformation occurs on the beams’ gage length. The stress is uniformly distributed over the three beams with a difference less than 0.5% among them. Both UV-LIGA fabricated nickel and SU-8 specimens have been tested. The UV-LIGA fabricated nickel has fracture strength of 1000±70 MPa and the results of SU-8 show a brittle behavior with fracture strength of 48±3 MPa.