Tensile Stress Reduction and Strain Concentration of Epoxy Resin Caused by Heterogeneity: A Multiscale Approach Combining Molecular Dynamics Simulation and Finite Element Method

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作者: Shoji, Naoyuki ; Yamashita, Takefumi

In this study, we investigated the effect of heterogeneity on the mechanical properties of epoxy resin by combining coarse-grained molecular dynamics (CG-MD) and finite element method (FEM) simulations. To evaluate the heterogeneity effect in the uniaxial elongation, heterogeneous and homogeneous FEM models of micrometer-scale cubic epoxy resin were constructed. For the heterogeneous FEM model, parameters of nanometer-scale elements were determined by CG-MD simulations, where nanometer-scale blocks have different cross-linked structures. For the homogeneous FEM model, the averaged parameters were used for all elements. The calculated stress-strain (S-S) curves of the heterogeneous model exhibit similar tensile stress values when compared to the experimental data, whereas the homogeneous model yields notably higher values. Moreover, a clear strain concentration associated with the formation of the shear band-like structure was observed in the heterogeneous model and not in the homogeneous model.

2022-03-31·Cement Science and Concrete Technology

STUDY ON REINFORCEMENT METHOD FOR PLAIN CONCRETE CANAL TUNNEL LINING USING CFRP STRAND SHEET

作者: MORI, Mitsuhiro ; ISHII, Masayuki ; SAKURAI, Shunta ; HORIKOSHI, Naoki

There are many reports of various deformations and damages, such as cracks, deformation and flaking of the lining concrete in actual canal tunnel structures, and it is necessary to restore the function through repair and reinforcement.The authors developed an internal reinforcement method using CFRP strand sheets and ceramic mixed epoxy resin mortar for an agricultural canal tunnel lining where bending cracks were observed on the inner surface of the lining.Various elemental tests on the method were conducted, and it was confirmed that the method showed excellent long-term adhesion performance in water, water permeability and wear resistance in the environment of agricultural canal tunnels, which are in contact with water for a long time.In addition, in order to verify the reinforcement effect, two types of full-scale tunnel model specimens, one reinforced by this method and the other reinforced after cracks were generated in the plain concrete lining in advance, were fabricated, and loading tests were conducted on the specimens.As a result, although the initial stiffness was different, the two types of specimens show similar load bearing capacity and deformation performance in the ultimate state.Therefore, the effectiveness of this method as a reinforcement method for agricultural canal tunnels was confirmed.

2021-12-01·Journal of The Adhesion Society of Japan

Properties of a Novel Crystalline Polymer Obtained from an EpoxyResin Having a Diphenylene Ether Structure and4,4’-dihydroxybiphenyl

作者: OGAMI, Koichiro ; KAJI, Masashi

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2023-11-30

·Fresenius

Fresenius successfully completes deconsolidation of Fresenius Medical Care

Contact Stefan Schmidt T +49 (0) 175 45 43 556 stefan.schmidt@fresenius.com Documents Text as PDF document (PDF, 108 KB) Deconsolidation is a landmark in the implementation of the #FutureFresenius program and a historic day for both companies Reducing complexity is a prerequisite for greater flexibility as well as more efficient and faster decision-making and the basis for long-lasting economic success Fresenius remains the largest shareholder of Fresenius Medical Care with an unchanged 32 percent of the share capital Fresenius has successfully completed the deconsolidation of Fresenius Medical Care: The change in legal form was entered in the commercial register on November 30, 2023, and thereby took effect after the Senate of the Bamberg Higher Regional Court had granted Fresenius Medical Care's applications for approval in full. "The deconsolidation of Fresenius Medical Care is a landmark in the implementation of our #FutureFresenius strategy and a historic day for both companies. We are reducing complexity and creating the conditions for greater flexibility and more efficient and faster decision-making. Fresenius Medical Care will gain a greater degree of freedom as a result of the deconsolidation. This also means greater responsibility. Both companies can now concentrate on what they do best: working for the well-being of patients in their respective segments," said Michael Sen, CEO of Fresenius. "We are redirecting the company's focus with #FutureFresenius and creating the basis for long-lasting economic success. The solid business performance in recent quarters shows that this is the right path for us." The shareholders of Fresenius Medical Care had already approved the change in legal form from a partnership limited by shares (KGaA) to a stock corporation (AG) by a majority of more than 99% at an Extraordinary General Meeting held on July 14, 2023. Following the change in legal form, Fresenius Medical Care is no longer part of the consolidated subsidiaries of Fresenius. Fresenius continues to hold 32 percent of Fresenius Medical Care's share capital and therefore remains the company's largest shareholder. With the deconsolidation, Fresenius Medical Care's accounting treatment will change from IFRS 5 to equity method accounting. Fresenius Medical Care was formed in 1996 from the merger of Fresenius' dialysis division with the U.S. dialysis provider National Medical Care (NMC). The combination of Fresenius' product business and NMC's service business has made the company the world's leading and uniquely vertically integrated dialysis provider. Since then, Fresenius Medical Care has increased considerably in size and value as a result of organic growth and acquisitions: Revenue and the number of patients have increased sevenfold, while the number of employees has increased fivefold.

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