PREDICTING PROCESSING INDUCED RESIDUAL- STRESSES IN CARBON FIBER-THERMOPLASTIC MICRO-COMPOSITES

2021 ◽  
Author(s):  
NITHIN K. PARAMBIL ◽  
BRANNDON R. CHEN ◽  
JOSEPH M. DEITZEL ◽  
JOHN W. GILLESPIE, JR. ◽  
LOAN T. VO ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
Residual Strain ◽  
Coefficient Of Thermal Expansion ◽  
Fiber Composite ◽  
Transversely Isotropic ◽  
Axial Direction ◽  
Single Fiber ◽  
Temperature Dependent ◽  
Test Configuration ◽  
Polypropylene Composites

A computational model of residual stress is developed for AS4/polypropylene composites and implemented via user material subroutine (UMAT) in ABAQUS. The main factors included in the model are the cooling-rate dependent crystallinity, temperature-dependent elastic modulus, and temperature-dependent coefficient of thermal expansion (CTE) of the matrix, and the temperature-independent transversely isotropic properties of the carbon fiber. Numerical results are generated for the case of a single fiber embedded in a thin film of polypropylene sample to replicate the process history and test configuration. During single fiber composite processing, a precalculated weight (tensile preload) is applied at the fiber ends to eliminate buckling/waviness of the carbon fiber induced by matrix shrinkage in the axial direction of the fiber. Experiments and Finite element (FE) analysis have been conducted with different preloads (1g, 4g, and 8g) at 25°C. Micro-Raman spectroscopy is utilized to validate the residual strain with different preloads at the bulk. The measured strain values show a good correlation with the predicted residual strain for various preload conditions.

Self-Adaptable Carbon Fiber Composite

2018 ◽  
Author(s):  
Arnaldo Casalotti ◽  
Krishna C. Chinnam ◽  
Giulia Lanzara
Keyword(s):  
Carbon Fiber ◽  
Smart Materials ◽  
Structural Integrity ◽  
Fiber Composite ◽  
Carbon Fiber Composites ◽  
Smart Composite ◽  
Temperature Dependent ◽  
Carbon Fiber Composite ◽  
Composite Layers ◽  
Actual Material

This article illustrates an approach to develop innovative smart materials based on carbon fiber composites. The proposed approach relies on the use of ultra-light strain sensors that are embedded into the composite and are adopted to monitor in real-time the actual material configuration. Such sensors are composed of electrospun PVDF fibers that exploit piezoelectricity to identify strain and thanks to their extreme lightweight can easily be embedded within the composite layers without affecting the structural integrity. On the other hand, the composite is equipped with a system of internal distributed heaters that can locally and globally vary the composite temperature. Since the adopted epoxy has a considerable temperature-dependent behaviour, it is possible to control its stiffness and thus to control the structural frequencies and damping. By coupling the sensing system with the control system, the structural properties are tuned to match prescribed working conditions, thus optimizing the performance of the proposed smart system. The proposed approach is investigated experimentally by manufacturing prototypes of the smart composite and by performing multiple tests to study the material response and evaluate the obtained performance.

Cytocompatibility of Carbon Nanofiber Materials for Neural Applications

2003 ◽  
Vol 774 ◽  
Author(s):  
Janice L. McKenzie ◽  
Michael C. Waid ◽  
Riyi Shi ◽  
Thomas J. Webster
Keyword(s):  
Carbon Fiber ◽  
Surface Energy ◽  
Carbon Nanofibers ◽  
Carbon Fibers ◽  
Carbon Nanofiber ◽  
Fiber Composite ◽  
Scar Tissue ◽  
Pc 12 Cells ◽  
Low Surface Energy ◽  
Poly Carbonate

AbstractSince the cytocompatibility of carbon nanofibers with respect to neural applications remains largely uninvestigated, the objective of the present in vitro study was to determine cytocompatibility properties of formulations containing carbon nanofibers. Carbon fiber substrates were prepared from four different types of carbon fibers, two with nanoscale diameters (nanophase, or less than or equal to 100 nm) and two with conventional diameters (or greater than 200 nm). Within these two categories, both a high and a low surface energy fiber were investigated and tested. Astrocytes (glial scar tissue-forming cells) and pheochromocytoma cells (PC-12; neuronal-like cells) were seeded separately onto the substrates. Results provided the first evidence that astrocytes preferentially adhered on the carbon fiber that had the largest diameter and the lowest surface energy. PC-12 cells exhibited the most neurites on the carbon fiber with nanodimensions and low surface energy. These results may indicate that PC-12 cells prefer nanoscale carbon fibers while astrocytes prefer conventional scale fibers. A composite was formed from poly-carbonate urethane and the 60 nm carbon fiber. Composite substrates were thus formed using different weight percentages of this fiber in the polymer matrix. Increased astrocyte adherence and PC-12 neurite density corresponded to decreasing amounts of the carbon nanofibers in the poly-carbonate urethane matrices. Controlling carbon fiber diameter may be an approach for increasing implant contact with neurons and decreasing scar tissue formation.

Prestressed Carbon Fiber Composite Overwrapped Gun Tube

2008 ◽  
Author(s):  
Andrew Littlefield ◽  
Edward Hyland ◽  
Jack Keating
Keyword(s):  
Carbon Fiber ◽  
Fiber Composite ◽  
Carbon Fiber Composite
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