scholarly journals Viscoelastic Behavior of Glass-Fiber-Reinforced Silicone Composites Exposed to Cyclic Loading

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 1862 ◽  
Author(s):  
Julia Beter ◽  
Bernd Schrittesser ◽  
Bernhard Lechner ◽  
Mohammad Reza Mansouri ◽  
Claudia Marano ◽  
...  
Keyword(s):  
Cyclic Loading ◽  
Fiber Orientation ◽  
Mechanical Performance ◽  
Glass Fibers ◽  
Matrix Material ◽  
Viscoelastic Behavior ◽  
Fiber Reinforced ◽  
Step Cycle ◽  
Dynamic Mechanical

The aim of this work was to analyze the influence of fibers on the mechanical behavior of fiber-reinforced elastomers under cyclic loading. Thus, the focus was on the characterization of structure–property interactions, in particular the dynamic mechanical and viscoelastic behavior. Endless twill-woven glass fibers were chosen as the reinforcement, along with silicone as the matrix material. For the characterization of the flexible composites, a novel testing device was developed. Apart from the conventional dynamic mechanical analysis, in which the effect of the fiber orientation was also considered, modified step cycle tests were conducted under tensile loading. The material viscoelastic behavior was studied, evaluating both the stress relaxation response and the capability of the material to dissipate energy under straining. The effects of the displacement rate of the strain level, the amplitude of the strain applied in the loading–unloading step cycle test, and the number of the applied cycles were evaluated. The results revealed that an optimized fiber orientation leads to 30-fold enhanced stiffness, along with 10 times higher bearable stress. The findings demonstrated that tailored reinforced elastomers with endless fibers have a strong influence on the mechanical performance, affecting the structural properties significantly.

scholarly journals Role of smooth muscle activation in the static and dynamic mechanical characterization of human aortas

2022 ◽  
Vol 119 (3) ◽  
pp. e2117232119
Author(s):  
Giulio Franchini ◽  
Ivan D. Breslavsky ◽  
Francesco Giovanniello ◽  
Ali Kassab ◽  
Gerhard A. Holzapfel ◽  
...  
Keyword(s):  
Experimental Data ◽  
Smooth Muscle ◽  
Muscle Activation ◽  
Mechanical Response ◽  
Mechanical Characterization ◽  
Viscoelastic Behavior ◽  
Material Model ◽  
Suitable Material ◽  
Dynamic Mechanical

Experimental data and a suitable material model for human aortas with smooth muscle activation are not available in the literature despite the need for developing advanced grafts; the present study closes this gap. Mechanical characterization of human descending thoracic aortas was performed with and without vascular smooth muscle (VSM) activation. Specimens were taken from 13 heart-beating donors. The aortic segments were cooled in Belzer UW solution during transport and tested within a few hours after explantation. VSM activation was achieved through the use of potassium depolarization and noradrenaline as vasoactive agents. In addition to isometric activation experiments, the quasistatic passive and active stress–strain curves were obtained for circumferential and longitudinal strips of the aortic material. This characterization made it possible to create an original mechanical model of the active aortic material that accurately fits the experimental data. The dynamic mechanical characterization was executed using cyclic strain at different frequencies of physiological interest. An initial prestretch, which corresponded to the physiological conditions, was applied before cyclic loading. Dynamic tests made it possible to identify the differences in the viscoelastic behavior of the passive and active tissue. This work illustrates the importance of VSM activation for the static and dynamic mechanical response of human aortas. Most importantly, this study provides material data and a material model for the development of a future generation of active aortic grafts that mimic natural behavior and help regulate blood pressure.

scholarly journals Influence of Fiber Orientation on Impact Resistance Behavior of Woven Sisal Fiber Reinforced Polyester Composite

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Genetu A. Dress ◽  
M. H. Woldemariam ◽  
D. T. Redda
Keyword(s):  
Fiber Orientation ◽  
Test Specimen ◽  
Impact Resistance ◽  
Impact Testing ◽  
Sisal Fiber ◽  
Fiber Reinforced ◽  
Average Impact ◽  
Polyester Composite ◽  
Izod Impact

Woven natural fiber reinforced polymer composites have better tensile, flexural, and compressive strength compared to the mechanical properties of unidirectional and randomly oriented NFRPC because of the interlacing of fiber bundles. However, the characterization of impact behavior with different fiber orientation such as 30°/60°, 0/90°, 30°/−45°, and 45°/−45° woven sisal fiber reinforced polyester composite was not studied vigorously. Thus, this paper focuses on the experimental characterization of the impact resistance behavior on woven sisal fiber reinforced polyester composite materials for semistructural part by using Izod impact testing setup. The 30°/60°, 30°/−45°, 0°/90°, and 45°/−45° woven sisal fiber was prepared using nailed wooden frame as a warp and weft guider. The woven sisal fiber was impregnated in order to make woven sisal fiber dimensionally stable. Using 40% by weight of fiber and 60% by weight of polyester, the composite was developed using hand layup process. The morphology and cross-sectional elemental detection was carried out using scanning electron microscope (SEM) assessment in leather development institute (LDI). Finally, impact tests were carried out using Izod impact testing setup in Addis Ababa Science and Technology University (ASTU). The average impact strength of a 40 wt% fiber 45°/−45° woven sisal fiber reinforced unsaturated polyester composite (WSFRPC) test specimen with consecutive warp and weft tow spacing of 2 mm was 342.67 J/m and this was greater energy compared to the other orientations. But the average impact strength of a 40 wt% fiber 30°/60° WSFRPC of test specimen with consecutive warp and weft tow spacing of 2 mm was 241.33 J/m.

scholarly journals Fiber Orientation Predictions—A Review of Existing Models

2020 ◽  
Vol 4 (2) ◽  
pp. 69 ◽  
Author(s):  
Susanne Katrin Kugler ◽  
Armin Kech ◽  
Camilo Cruz ◽  
Tim Osswald
Keyword(s):  
Fiber Orientation ◽  
Mechanical Performance ◽  
Historical Review ◽  
Fiber Reinforced Polymers ◽  
Strong Impact ◽  
Fiber Reinforced ◽  
Reinforced Polymers ◽  
Virtual Engineering ◽  
Rotary Diffusion ◽  
Orientation Phenomenon

Fiber reinforced polymers are key materials across different industries. The manufacturing processes of those materials have typically strong impact on their final microstructure, which at the same time controls the mechanical performance of the part. A reliable virtual engineering design of fiber-reinforced polymers requires therefore considering the simulation of the process-induced microstructure. One relevant microstructure descriptor in fiber-reinforced polymers is the fiber orientation. This work focuses on the modeling of the fiber orientation phenomenon and presents a historical review of the different modelling approaches. In this context, the article describes different macroscopic fiber orientation models such as the Folgar-Tucker, nematic, reduced strain closure (RSC), retarding principal rate (RPR), anisotropic rotary diffusion (ARD), principal anisotropic rotary diffusion (pARD), and Moldflow rotary diffusion (MRD) model. We discuss briefly about closure approximations, which are a common mathematical element of those macroscopic fiber orientation models. In the last section, we introduce some micro-scale numerical methods for simulating the fiber orientation phenomenon, such as the discrete element method (DEM), the smoothed particle hydrodynamics (SPH) method and the moving particle semi-implicit (MPS) method.

scholarly journals A Flow-Dependent Fiber Orientation Model

2020 ◽  
Vol 4 (3) ◽  
pp. 96
Author(s):  
Susanne Katrin Kugler ◽  
Argha Protim Dey ◽  
Sandra Saad ◽  
Camilo Cruz ◽  
Armin Kech ◽  
...  
Keyword(s):  
Fiber Orientation ◽  
Mechanical Performance ◽  
Mechanistic Model ◽  
Elongational Flow ◽  
Simulation Software ◽  
Fiber Reinforced Polymers ◽  
Macroscopic Model ◽  
Fluid Viscosity ◽  
Fiber Reinforced ◽  
Elongational Flows

The mechanical performance of fiber reinforced polymers is dependent on the process-induced fiber orientation. In this work, we focus on the prediction of the fiber orientation in an injection-molded short fiber reinforced thermoplastic part using an original multi-scale modeling approach. A particle-based model developed for shear flows is extended to elongational flows. This mechanistic model for elongational flows is validated using an experiment, which was conducted for a long fiber reinforced polymer. The influence of several fiber descriptors and fluid viscosity on fiber orientation under elongational flow is studied at the micro-scale. Based on this sensitivity analysis, a common parameter set for a continuum-based fiber orientation macroscopic model is defined under elongational flow. We then develop a novel flow-dependent macroscopic fiber orientation, which takes into consideration the effect of both elongational and shear flow on the fiber orientation evolution during the filling of a mold cavity. The model is objective and shows better performance in comparison to state-of-the-art fiber orientation models when compared to μCT-based fiber orientation measurements for several industrial parts. The model is implemented using the simulation software Autodesk Moldflow Insight Scandium® 2019.

Sign in / Sign up

Export Citation Format

Share Document