FEM simulation of elasto-plastic tube indentation

This work is supported by the SGS 2018 TUL grant 21120 provided by the Ministry of Education, Youth and Sports of the Czech Republic.Paper provides the summary of the FEM simulation of elasto-plastic strains and stresses in the course of the local indentation of a steel pipe by a spherical indenter. The FEM calculation was performed according to the recommendation of API 579-1 / ASME FFS-1 2007 for Level 3 dent assessment. Series of 65 FE calculations of the elasto-plastic state of the indented tubes was performed. The combination of three tube diameters D = 508, 920 and 1420 mm with the ratios between the diameter and the wall thickness D/h = 91, 76, 64, 51 and 37 resp. were used. The diameters of the spherical rigid indenters were 100 and 200 mm, the depth of the indent varied gradually from 75 to 150 mm. The residual stresses and strains in the vicinity of the dent after the relieving of load were determined together with the depth and length of the resulting dent

Numerical computation of stress relaxation of isotropic magnetorheological elastomer using fractional viscoelastic models

This work was supported by the Ministry of Education, Youth and Sports of the Czech Republic and the European Union European Structural and Investment Funds in the frames of Operational Program Research, Development and Education - project Hybrid Materials for Hierarchical Structures (HyHi, Reg. No.CZ.02.1.01/0.0/0.0/16_019/0000843)

Impact and post impact behavior of fabric reinforced geopolymer composite

International audienceImpact and post impact behavior of fabric reinforced geopolymer composites is investigated in this study. Carbon, E-glass and basalt fabrics are incorporated in the geopolymer matrix. The geopolymer composites are tested for impact resistance to an out-of-plane low velocity impact test, followed by post impact performance testing using residual strength measurement on the sample. Impact properties such as impact energy, energy absorption capacity, and damaged area of the composites were examined for fabric reinforced geopolymer composite samples. The drop weight impact tests were performed on composite samples of 15 × 15 cm. The quality of the samples was examined using C-scan in ultrasonic vibration mode and μCT before and after impact test. The post impact behavior of the composite samples was characterized using four point bending tests. Fiber orientation and alignment was observed using SEM. The results obtained showed that E-glass fabric reinforced composites show slightly better performance than carbon reinforced composites. Especially the damaged area is smaller for E glass composites. Basalt fabric reinforced composites have low bending strength and very low impact resistance. The energy absorption in E-glass is due to post-debond fiber sliding phenomena and in carbon fiber to fiber pull out from the composite. The smaller damaged area is attributed to the higher elastic energy absorption of E-glass fibers. The residual strength of carbon and E-glass composites decreased in relation to the size of the visually damaged area, meaning that no invisible damage took place. © 2016 Elsevier Lt