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H. Bangert, A. Kaminitschek and A. Wagendristel
Hardness testing using a SEM offers visual observation and measurement according to the hardness definition even for submicroscopic impressions. It can provide information…
Hardness testing using a SEM offers visual observation and measurement according to the hardness definition even for submicroscopic impressions. It can provide information on plasticity, homogeneity, adhesion etc. which cannot be obtained from depth measurements alone. The device described operates inside a SEM and offers a load between 10−2N and 10−5N. The influence of test load, rate of load increase and dwell time on the results was examined on various materials.
This paper gives a bibliographical review of the finite element modelling and simulation of indentation testing from the theoretical as well as practical points of view…
This paper gives a bibliographical review of the finite element modelling and simulation of indentation testing from the theoretical as well as practical points of view. The bibliography lists references to papers, conference proceedings and theses/dissertations that were published between 1990 and 2002. At the end of this paper, 509 references are listed dealing with subjects such as, fundamental relations and modelling in indentation testing, identification of mechanical properties for specific materials, fracture mechanics problems in indentation, scaling relationship for indentation, indenter geometry and indentation testing.
The Deutscher Verband für Schweisstechnik (German Welding Society) made a very judicious and much appreciated choice of venue for its Third International Conference on…
The Deutscher Verband für Schweisstechnik (German Welding Society) made a very judicious and much appreciated choice of venue for its Third International Conference on 18–20 February, 1986, on Interconnection Technology in Electronics. Fellbach, less than 10 km from the Schlossplatz in Stuttgart, and whose past profile was shaped almost entirely by winegrowing, has become since the opening in 1976 of the Schwabenlandhalle a town renowned equally for its significance as a conference centre. With the vine‐crowned Kappelberg hill dominating the town and commanding views to the Neckar Valley, Swabian hospitality and friendliness at its best, and a most impressive congress hall with excellent facilities in picturesque snow‐clad surroundings, the ingredients for providing a conference venue conducive to an optimum interchange of technological information were certainly present.
Zuu‐Chang Hong, Ching Lin and Ming‐Hua Chen
A transport equation for the one‐point velocity probability densityfunction (pdf) of turbulence is derived, modelled and solved. The new pdfequation is obtained by two…
A transport equation for the one‐point velocity probability density function (pdf) of turbulence is derived, modelled and solved. The new pdf equation is obtained by two modeling steps. In the first step, a dynamic equation for the fluid elements is proposed in terms of the fluctuating part of Navier‐Stokes equation. A transition probability density function (tpdf) is extracted from the modelled dynamic equation. Then the pdf equation of Fokker‐Planck type is obtained from the tpdf. In the second step, the Fokker‐Planck type pdf equation is modified by Lundgren’s formal pdf equation to ensure it can properly describe the turbulence intrinsic mechanism. With the new pdf equation, the turbulent plane Couette flow is solved by the direct finite difference method coupled with dimensionality reduction and QUICKER scheme. A simple boundary treatment is proposed such that the near‐wall solution is tractable and then no refined grid is required. The calculated mean velocity, friction coefficient, and turbulence structure are in good agreement with available experimental data. In the region departed from the center of flow field, the contours of isojoint pdf of V1 and V2 is very similar to that of experimental result of channel flow. These agreements show the validity of the new pdf model and the availability of the boundary treatment and QUICKER scheme for solving the turbulent plane Couette flow.
Mary E. Kinsella, Blaine Lilly, Benjamin E. Gardner and Nick J. Jacobs
To determine static friction coefficients between rapid tooled materials and thermoplastic materials to better understand ejection force requirements for the injection…
To determine static friction coefficients between rapid tooled materials and thermoplastic materials to better understand ejection force requirements for the injection molding process using rapid‐tooled mold inserts.
Static coefficients of friction were determined for semi‐crystalline high‐density polyethylene (HDPE) and amorphous high‐impact polystyrene (HIPS) against two rapid tooling materials, sintered steel with bronze (LaserForm ST‐100) and stereolithography resin (SL5170), and against P‐20 mold steel. Friction tests, using the ASTM D 1894 standard, were run for all material pairs at room temperature, at typical part ejection temperatures, and at ejection temperatures preceded by processing temperatures. The tests at high temperature were designed to simulate injection molding process conditions.
The friction coefficients for HDPE were similar on P‐20 Steel, LaserForm ST‐100, and SL5170 Resin at all temperature conditions. The HIPS coefficients, however, varied significantly among tooling materials in heated tests. Both polymers showed highest coefficients on SL5170 Resin at all temperature conditions. Friction coefficients were especially high for HIPS on the SL5170 Resin tooling material.
Applications of these findings must consider that elevated temperature tests more closely simulated the injection‐molding environment, but did not exactly duplicate it.
The data obtained from these tests allow for more accurate determination of friction conditions and ejection forces, which can improve future design of injection molds using rapid tooling technologies.
This work provides previously unavailable friction data for two common thermoplastics against two rapid tooling materials and one steel tooling material, and under conditions that more closely simulate the injection‐molding environment.
The primary purpose of this study is to introduce a method of using former students’ advice and learning experiences to affect subsequent students’ thoughts and beliefs…
The primary purpose of this study is to introduce a method of using former students’ advice and learning experiences to affect subsequent students’ thoughts and beliefs about accounting learning in a positive way thereby improving their academic performance.
At the end of Fall 2009, the instructor invited the students to give suggestions to future accounting students about their learning experiences. On the first days of the following three semesters, I showed the feedback to the subsequent students. I recommended that the students read the suggestions after class and throughout the semester when necessary. I also conduct the survey to collect the students’ perceptions on the usefulness of former students’ advice. Analyses are conducted to assess the impact of the students’ advice on class attendance, exam performance, and the dropout rate for the course.
The results show that former students’ advice and learning experiences can help subsequent students improve class attendance, course performance, and the drop rate.
The study provides a useful and easy-to-adopt learning supplement to help students succeed in a course that many students find challenging. The study also gives educators a simple but useful and efficient way to achieve greater student involvement in their learning processes.
To the best of my knowledge, this study is the first to focus on the impact of former students’ advice and learning experience on the following students’ learning performance in accounting education.
Josef Eberhardsteiner, Günter Hofstetter, Günther Meschke and Peter Mackenzie‐Helnwein
In this paper, three research topics are presented referring to different aspects of multifield problems in civil engineering. The first example deals with long term…
In this paper, three research topics are presented referring to different aspects of multifield problems in civil engineering. The first example deals with long term behaviour of wood under multiaxial states of stress and the effect of moisture changes on the deformation behaviour of wood. The second example refers to the application of a three‐phase model for soils to the numerical simulation of dewatering of soils by means of compressed air. The soil is modelled as a three phase‐material, consisting of the deformable soil skeleton and the fluid phases – water and compressed air. The third example is concerned with computational durability mechanics of concrete structures. As a particular example of chemically corrosive mechanisms, the material degradation due to the dissolution of calcium and external loading is addressed.