scholarly journals Time-Dependent Material Properties of Shotcrete: Experimental and Numerical Study

Materials ◽  
2017 ◽  
Vol 10 (9) ◽  
pp. 1067 ◽  
Author(s):  
Matthias Neuner ◽  
Tobias Cordes ◽  
Martin Drexel ◽  
Günter Hofstetter
Keyword(s):  
Material Properties ◽  
Numerical Study ◽  
Time Dependent

Application of a Viscoelastic Model for Polyester Mooring

2010 ◽  
Author(s):  
J. W. Kim ◽  
J. H. Kyoung ◽  
A. Sablok
Keyword(s):  
Material Properties ◽  
Viscoelastic Model ◽  
Practical Method ◽  
Time Dependent ◽  
Mooring Line ◽  
New Model ◽  
Global Performance ◽  
Excitation Period ◽  
Linear Viscoelastic ◽  
Floating Platforms

A new practical method to simulate time-dependent material properties of polyester mooring line is proposed. The time-dependent material properties of polyester rope are modeled with a standard linear solid (SLS) model, which is one of the simplest forms of a linear viscoelastic model. The viscoelastic model simulates most of the mechanical properties of polyester rope such as creep, strain-stress hysteresis and excitation period-dependent stiffness. The strain rate-stress relation of the SLS model has been re-formulated to a stretch-tension relation, which is more suitable for implementation into global performance and mooring analyses tools for floating platforms. The new model has been implemented to a time-domain global performance analysis software and applied to simulate motion of a spar platform with chain-polyester-chain mooring system. The new model provides accurate platform offset without any approximation on the mean environmental load and can simulate the transient effect due to the loss of a mooring line during storm conditions, which has not been possible to simulate using existing dual-stiffness models.

Numerical Study of the Effect of Geometry and Boundary Conditions on the Collapse Behaviour of Stocky Stiffened Panels

2012 ◽  
Vol 154 (A2) ◽  
Keyword(s):  
Finite Element ◽  
Boundary Conditions ◽  
Ultimate Strength ◽  
Material Properties ◽  
Finite Element Modelling ◽  
Numerical Study ◽  
Fe Analysis ◽  
Stiffened Panels ◽  
Element Modelling ◽  
Geometric Configurations

This study aims at studying different configurations of the stiffened panels in order to identify robust configurations that would not be much sensitive to the imprecision in boundary conditions that can exist in experimental set ups. A numerical study is conducted to analyze the influence of the stiffener’s geometry and boundary conditions on the ultimate strength of stiffened panels under uniaxial compression. The stiffened panels with different combinations of mechanical material properties and geometric configurations are considered. The four types of stiffened panels analysed are made of mild or high tensile steel and have bar, ‘L’ and ‘U’ stiffeners. To understand the effect of finite element modelling on the ultimate strength of the stiffened panels, four types of FE models are investigated in FE analysis including 3 bays, 1/2+1+1/2 bays, 1+1 bays and 1 bay with different boundary conditions.

scholarly journals Impact of Enzymatic Degradation on the Material Properties of Poly(Ethylene Terephthalate)

Polymers ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 3885
Author(s):  
Teresa Menzel ◽  
Sebastian Weigert ◽  
Andreas Gagsteiger ◽  
Yannik Eich ◽  
Sebastian Sittl ◽  
...  
Keyword(s):  
Material Properties ◽  
Enzymatic Degradation ◽  
Ethylene Terephthalate ◽  
Compact Tension ◽  
Time Dependent ◽  
Material Failure ◽  
Near Surface ◽  
Poly Ethylene Terephthalate ◽  
Poly Ethylene ◽  
The Impact

With macroscopic litter and its degradation into secondary microplastic as a major source of environmental pollution, one key challenge is understanding the pathways from macro- to microplastic by abiotic and biotic environmental impact. So far, little is known about the impact of biota on material properties. This study focuses on recycled, bottle-grade poly(ethylene terephthalate) (r-PET) and the degrading enzyme PETase from Ideonella sakaiensis. Compact tension (CT) specimens were incubated in an enzymatic solution and thermally and mechanically characterized. A time-dependent study up to 96 h revealed the formation of steadily growing colloidal structures. After 96 h incubation, high amounts of BHET dimer were found in a near-surface layer, affecting crack propagation and leading to faster material failure. The results of this pilot study show that enzymatic activity accelerates embrittlement and favors fragmentation. We conclude that PET-degrading enzymes must be viewed as a potentially relevant acceleration factor in macroplastic degradation.

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