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1

Predictions of fracture resistance of spruce wood under mixed mode loading using non-local fracture theory and numerical modelling

Romanowicz Marek

Journal of Theoretical and Applied Mechanics

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2023

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Vol. 61 nr 1

147--162

EN

A novel analytical model to predict fracture resistance of a quasi-brittle material, like wood, is presented. The model is based on a scaling parameter introduced into the non-local fracture theory to take into account the specimen size effect on the development of the damage zone. An expression for length of the critical process zone, which can be used in damage tolerant design of wooden structures is derived from this theory. The model is validated with mixedmode bending tests. A numerical analysis using cohesive elements is performed to understand the role of specimen size in the development of the damage zone. The analytical predictions of the fracture resistance and the critical process zone length for wood are compared with numerical results and experimental data available in the literature.

2

Experimental and Theoretical Investigation of Galvanized Steel and Fiber-Reinforced Polymer Composites Textile Adhesive Double Lap Joints

Dybizbański Maciej Adam, Rzeszut Katarzyna

Advances in Science and Technology. Research Journal

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2023

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Vol. 17, no 4

110--120

EN

This paper presents an experimental analysis of CFRP fabric to galvanized steel adhesive connection. An experimental research has been conducted on the adhesive connection between CFRP fabric and galvanized steel subjected to shear forces. The specimens were made from the steel plates overlapped on both sides with SikaWrap 230 C fabric using SikaDur 330 adhesive. Observations of natures of failure for CFRP-Steel adhesive connection were conducted based on visual inspection using a scanning microscope. Mixed nature of the connection failure was specified. Moreover, an advanced numerical model has been developed and later on validated and verified on the basis of performed original laboratory tests. Ultimately, final conclusions were drawn based on the advanced numerical model that has been developed, verified and validated using laboratory tests results, as well as analytical models and nature of the connection failure was specified.

3

Stability and failure of thin-walled composite structures with a square cross-section

Czajka Błażej, Różyło Patryk, Dębski Hubert

Applied Computer Science

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2022

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Vol. 18, no 2

43--55

EN

This paper is devoted to the analysis of the stability and load-carrying capacity of thin-walled composite profiles in compression. The specimens reflect elements made of carbon fibre reinforced laminate (CFRP). Thin-walled columns with a square cross-section were made from 4 layers of composite in 3 different combinations of layer arrangements. Advanced numerical analyses have been carried out. In the first stage of the study, a buckling analysis of the structure was performed. In further numerical simulations, two advanced models were used simultaneously: the Progressive Failure Analysis (PFA) and the Cohesive Zone Model (CZM). The results showed significant differences between the critical load values for each layer configuration. The forms of buckling and the areas of damage initiation and evolution were also dependent on the applied layup.

4

Static and dynamic debonding strength of bundled glass fibers

Gunavan F. E.

Archive of Mechanical Engineering

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2018

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Vol. LXV, nr 2

209--220

EN

Experimental design and computational model for predicting debonding initiation and propagation are of interest of scientists and engineers. The design and model are expected to explain the phenomenon for a wide range of loading rates. In this work, a method to measure and quantify debonding strength at various loading rates is proposed. The method is experimentally veriﬁed using data obtained from a static test and a pulse-type dynamic test. The proposed method involves the cohesive zone model, which can uniquely be characterized with a few parameters. Since those parameters are diﬃcult to be measured directly, indirect inference is deployed where the parameters are inferred by minimizing discrepancy of mechanical response of a numerical model and that of the experiments. The main ﬁnding suggests that the design is easy to be used for the debonding characterization and the numerical model can accurately predict the debonding for the both loading cases.The cohesive strength of the stress-wave case is signiﬁcantly higher than that of the static case; meanwhile, the cohesive energy is twice larger.

5

Experimental characterization and numerical modeling of the mechanical behavior of half sandwich laminate in the context of blanking

Chen L., Clalsmeyer T., Tekkaya A. E.

Computer Methods in Materials Science

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2015

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Vol. 15, No.1

162--168

EN

In this short paper the complex mechanical behavior of an aluminum/low density polyethylene (LDPE) half sandwich sheet in the context of blanking is investigated. Suitable mechanical tests for the polymer and metal layer as well as the delamination behavior of the adhesive between these two layers were conducted. The main focus of this study is to create a finite-element (FE) model for the blanking process of sandwich structures. Material parameters for a Lemaitre-type damage model, a Drucker-Prager and a cohesive zone model are identified for the metal, the polymer and the adhesive, respectively. The experimental force-displacement curves obtained in a blanking process of a half sandwich sheet are compared with the predicted results of the FE model. The qualitative agreement of the predicted force-displacement curves with the experimental results is good. Recommendations concerning the improvement of the FE model are given based on the obtained results.

PL

W pracy badano złożone, mechaniczne zachowanie blach o strukturze kompozytowej typu sandwich zbudowanych z aluminium i polietylenu o niskiej gęstości (LDPE) w procesie wykrawania. Przeprowadzono testy mechaniczne dla warstwy polimeru i metalu a także badano proces delaminacji warstwy adhezyjnej. Głównym celem pracy było opracowanie modelu elementów skończonych (MES) zachowania się struktur kompozytowych typu sandwich w procesie wykrawania. W ramach zadania zidentyfikowano parametry modelu Lemaitre'a dla warstwy metalu, Druckera-Pragera dla polimeru oraz kohezji dla warstwy adhezyjnej. Zarejestrowane w trakcie procesu wykrawania materiału kompozytowego siły porównano z siłami obliczonymi modelem MES. Otrzymano dobrą jakościowo zgodność wyników. Na podstawie przeprowadzonych badań sformułowano wytyczne pozwalające na poprawę opracowanego modelu numerycznego.