scholarly journals Interrelation between Fiber–Matrix Interphasial Phenomena and Flexural Stress Relaxation Behavior of a Glass Fiber–Polymer Composite

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 978
Author(s):  
George C. Papanicolaou ◽  
Diana V. Portan ◽  
Lykourgos C. Kontaxis
Keyword(s):  
Stress Relaxation ◽  
Glass Fiber ◽  
Radial Distance ◽  
Relaxation Behavior ◽  
Fiber Reinforced Polymer ◽  
Time Dependent ◽  
Stress Relaxation Behavior ◽  
Reinforced Polymer ◽  
Fiber Matrix ◽  
Fiber Interaction

The response of fiber-reinforced polymer composites to an externally applied mechanical excitation is closely related to the microscopic stress transfer mechanisms taking place in the fiber–matrix interphasial region. In particular, in the case of viscoelastic responses, these mechanisms are time dependent. Defining the interphase thickness as the maximum radial distance from the fiber surface where a specific matrix property is affected by the fiber presence, it is important to study its variation with time. In the present investigation, the stress relaxation behavior of a glass fiber-reinforced polymer (GFRP) under flexural conditions was studied. Next, applying the hybrid viscoelastic interphase model (HVIM), developed by the first author, the interphase modulus and interphase thickness were both evaluated, and their variation with time during the stress relaxation test was plotted. It was found that the interphase modulus decreases with the radial distance, being always higher than the bulk matrix modulus. In addition, the interphase thickness increases with time, showing that during stress relaxation, fiber–matrix debonding takes place. Finally, the effect of fiber interaction on the interphase modulus was found. It is observed that fiber interaction depends on both the fiber–matrix degree of adhesion as well as the fiber volume fraction and the time-dependent interphase modulus.

Time-dependent pullout behavior of glass fiber reinforced polymer (GFRP) soil nail in sand

2015 ◽  
Vol 52 (6) ◽  
pp. 671-681 ◽  
Author(s):  
Cheng-Cheng Zhang ◽  
Hong-Hu Zhu ◽  
Qiang Xu ◽  
Bin Shi ◽  
Guo-Xiong Mei
Keyword(s):  
Glass Fiber ◽  
Fiber Reinforced Polymer ◽  
Time Dependent ◽  
Rheological Parameters ◽  
Fiber Reinforced ◽  
Glass Fiber Reinforced Polymer ◽  
Soil Nail ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced ◽  
Proposed Model

Glass fiber reinforced polymer (GFRP) materials are gaining increasing use in geotechnical engineering applications in recent years. The long-term performance of reinforced geostructures may be influenced by the rheological properties of GFRP soil nails or anchors. However, a clear understanding of this effect is lacking. This work aims to investigate the interaction between GFRP soil nail and sand under pullout conditions considering the time-dependent effect. A time-dependent model was proposed to describe the load–deformation characteristics of a GFRP soil nail during pullout. Laboratory pullout tests were performed using a load-controlled pullout apparatus to verify the effectiveness of the proposed model. Quasi-distributed fiber Bragg grating (FBG) optical fiber sensors were adhered on the pre-grooved GFRP soil nail to capture the variations of axial strain during testing. The test results are presented, interpreted, and discussed. It is shown that there is good agreement between the simulation results and the experimental data under low stress levels. Additionally, the impacts of model parameters on the predicted time-dependent pullout behavior of a GFRP soil nail were examined through parametric studies. The results indicate that the distributions of tensile force and GFRP–sand interfacial shear stress along the nail length are highly time dependent. The creep displacement of a GFRP soil nail is significantly influenced by the rheological parameters of the proposed model.

scholarly journals Time-Dependent Mechanical Properties in Polyetherimide 3D-Printed Parts Are Dictated by Isotropic Performance Being Accurately Predicted by the Generalized Time Hardening Model

Polymers ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 678 ◽  
Author(s):  
A. G. Salazar-Martín ◽  
A. A. García-Granada ◽  
G. Reyes ◽  
G. Gomez-Gras ◽  
J. M. Puigoriol-Forcada
Keyword(s):  
Mechanical Properties ◽  
Stress Relaxation ◽  
Relaxation Behavior ◽  
Time Dependent ◽  
Secondary Creep ◽  
Stress Relaxation Behavior ◽  
Build Orientation ◽  
Fused Deposition ◽  
3D Printed ◽  
Generalized Time

The Fused-Deposition Modelling (FDM) technique has transformed the manufacturing discipline by simplifying operational processes and costs associated with conventional technologies, with polymeric materials being indispensable for the development of this technology. A lack of quantification of viscoelastic/plastic behavior has been noted when addressing FDM parts with Polyetherimide (PEI), which is currently being investigated as a potential material to produce functional end-products for the aerospace and health industry. Primary and secondary creep along with stress relaxation tests have been conducted on FDM PEI specimens by applying stresses from 10 to 40 MPa for 100 to 1000 min. Specimens were 3D printed by varying the part build orientation, namely XY, YZ, and XZ. Creep results were fitted to the Generalized Time Hardening equation (GTH), and then this model was used to predict stress relaxation behavior. FDM PEI parts presented an isotropic creep and stress relaxation performance. The GTH model was proven to have a significant capacity to fit viscoelastic/plastic performances for each single build orientation (r > 0.907, p < 0.001), as well as a tight prediction of the stress relaxation behavior (r > 0.998, p < 0.001). Averaged-orientation coefficients for GTH were also closely correlated with experimental creep data (r > 0.958, p < 0.001) and relaxation results data (r > 0.999, p < 0.001). FDM PEI parts showed an isotropic time-dependent behavior, which contrasts with previous publications arguing the significant effect of part build orientation on the mechanical properties of FDM parts. These findings are strengthened by the high correlation obtained between the experimental data and the averaged-coefficient GTH model, which has been proven to be a reliable tool to predict time-dependent performance in FDM parts.

Helical milling response of glass fiber-reinforced polymer composite with carbon nanotube buckypaper interlayer

2019 ◽  
Vol 28 (6) ◽  
pp. 378-387 ◽  
Author(s):  
Xinrui Wang ◽  
Stephen Kirwa Melly ◽  
Nan Li ◽  
Gong-Dong Wang ◽  
Tian Peng ◽  
...  
Keyword(s):  
Glass Fiber ◽  
Polymer Composites ◽  
Fiber Reinforced Polymer ◽  
Helical Milling ◽  
Fiber Reinforced ◽  
Glass Fiber Reinforced Polymer ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced ◽  
Fiber Reinforced Polymer Composites ◽  
Fiber Matrix

Fiber-reinforced polymer composites are increasingly utilized in applications where both the weight and the strength of the components are critical as in the aerospace industry. However, the full utilization of these materials could be hindered by the weak out-of-plane properties which precipitate delamination. Carbon nanotubes (CNTs) have recently gained massive interests due to its superior mechanical properties, which are excellent for improving the fiber/matrix interface. The current study considered two specimens of glass fiber-reinforced polymer composites (with and without CNT buckypaper) and subjected them to two tests, namely interlaminar shear strength and helical milling tests. Results show that the CNTs increase the interlaminar strength of the laminates by about 25% and the images of the machined parts reveal a separation of layers (delamination) on the specimens without CNT while on the other hand uncovering a relatively good quality surface and a good fiber/matrix/CNT interface for the specimens with CNT.

scholarly journals Investigation into the Effect of Cutting Conditions in Turning on the Surface Properties of Filament Winding GFRP Pipe Rings

Machines ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 16
Author(s):  
Gabriel Mansour ◽  
Panagiotis Kyratsis ◽  
Apostolos Korlos ◽  
Dimitrios Tzetzis
Keyword(s):  
Surface Roughness ◽  
Glass Fiber ◽  
Process Parameters ◽  
Filament Winding ◽  
Numerical Control ◽  
Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Glass Fiber Reinforced Polymer ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced

There are numerous engineering applications where Glass Fiber Reinforced Polymer (GFRP) composite tubes are utilized, such as desalination plants, power transmission systems, and paper mill, as well as marine, industries. Some type of machining is required for those various applications either for joining or fitting procedures. Machining of GFRP has certain difficulties that may damage the tube itself because of fiber delamination and pull out, as well as matrix deboning. Additionally, short machining tool life may be encountered while the formation of powder like chips maybe relatively hazardous. The present paper investigates the effect of process parameters for surface roughness of glass fiber-reinforced polymer composite pipes manufactured using the filament winding process. Experiments were conducted based on the high-speed turning Computer Numerical Control (CNC) machine using Poly-Crystalline Diamond (PCD) tool. The process parameters considered were cutting speed, feed, and depth of cut. Mathematical models for the surface roughness were developed based on the experimental results, and Analysis of Variance (ANOVA) has been performed with a confidence level of 95% for validation of the models.

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