In Situ Investigation of the Kinematics of Ply Interfaces During Composite Manufacturing

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Sandeep Chava ◽  
Sirish Namilae
Keyword(s):  
Carbon Fiber ◽  
Experimental Approach ◽  
Image Correlation ◽  
Radius Of Curvature ◽  
Micro Computed Tomography ◽  
In Situ Investigation ◽  
Out Of Plane ◽  
Set Up ◽  
Induced Defects

Abstract The kinematics of composite ply interfaces critically affects both the manufacturing processes and deformation mechanisms and is often responsible for the formation of defects such as wrinkles and delamination. In the present work, processing-induced defects in a carbon fiber prepreg composite are evaluated by devising a novel in situ experimental approach. Carbon fiber prepreg laminates are cured in a specially designed autoclave with viewports with plies laid up on a mold with cylindrical tooling set up to maximize the ply-movement. Four-ply layup orientations of [90/90]s, [90/0]s, [90/45]s, and [90/−45]s and three-mold configurations with cylindrical tools of diameter 9.5 mm (3/8 in.), 12.7 mm (1/2 in.), and 15.9 mm (5/8 in.) are used for the parametric study. Strains, ply-movement, and formation of defects are observed in situ using digital image correlation (DIC) during the autoclave cure cycle, through the viewports. The processing-induced defects in the composite are further characterized by X-ray micro-computed tomography (micro-CT). We observed that the mold with the larger radius of curvature (15.9 mm cylinder) leads to higher strains in both in-plane directions and higher displacement in out of plane directions. The maximum average out-of-plane ply movement, as well as the largest wrinkle, are observed for [90/−45]s layup on the mold with the highest radius of curvature.

scholarly journals Characterization and ballistic performance of thin pre-damaged resin-starved aramid-fiber composite panels

2021 ◽  
pp. 004051752110134
Author(s):  
Cerise A Edwards ◽  
Stephen L Ogin ◽  
David A Jesson ◽  
Matthew Oldfield ◽  
Rebecca L Livesey ◽  
...  
Keyword(s):  
Fiber Composite ◽  
Plane Deformation ◽  
Ballistic Impact ◽  
Image Correlation ◽  
Composite Panel ◽  
Composite Panels ◽  
Micro Computed Tomography ◽  
Ballistic Performance ◽  
Low Level ◽  
Out Of Plane

Military personnel use protective armor systems that are frequently exposed to low-level damage, such as non-ballistic impact, wear-and-tear from everyday use, and damage during storage of equipment. The extent to which such low-level pre-damage could affect the performance of an armor system is unknown. In this work, low-level pre-damage has been introduced into a Kevlar/phenolic resin-starved composite panel using tensile loading. The tensile stress–strain behavior of this eight-layer material has been investigated and has been found to have two distinct regions; these have been understood in terms of the microstructure and damage within the composite panels investigated using micro-computed tomography and digital image correlation. Ballistic testing carried out on pristine (control) and pre-damaged panels did not indicate any difference in the V50 ballistic performance. However, an indication of a difference in response to ballistic impact was observed; the area of maximal local out-of-plane deformation for the pre-damaged panels was found to be twice that of the control panels, and the global out-of-plane deformation across the panel was also larger.

Out-of-Plane Strengthening of Masonry Walls with FRCM Composite Materials

2017 ◽  
Vol 747 ◽  
pp. 158-165 ◽  
Author(s):  
Alessandro Bellini ◽  
Andrea Incerti ◽  
Claudio Mazzotti
Keyword(s):  
Composite Materials ◽  
Failure Modes ◽  
Theoretical Models ◽  
Masonry Wall ◽  
Image Correlation ◽  
Vertical Position ◽  
Masonry Walls ◽  
Out Of Plane ◽  
Set Up ◽  
Innovative Techniques

Structural strengthening by using composite materials proved to be one of the most suitable solutions for reinforcing masonry buildings. In this framework, the focus point of the presented experimental study is to evaluate the out-of-plane behaviour of masonry walls strengthened with Fiber Reinforced Cementitious Matrix (FRCM) composites when subjected to horizontal actions, by analyzing and discussing failure modes and their out-of-plane capacity. To this purpose, a new experimental set-up was developed, capable of applying an axial force and out-of-plane horizontal actions on full-scale masonry panels, placed in vertical position and subjected to a stress state similar to that present on a real masonry wall. Experimental results, obtained by using traditional and innovative techniques (such as Digital Image Correlation), will be compared with those coming from more conventional tensile and bond tests performed on FRCM coupons applied on masonry substrates, making use of simple theoretical models.

scholarly journals Out-Of-Plane Permeability Evaluation of Carbon Fiber Preforms by Ultrasonic Wave Propagation

Materials ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 2684 ◽  
Author(s):  
Francesca Lionetto ◽  
Francesco Montagna ◽  
Alfonso Maffezzoli
Keyword(s):  
Wave Propagation ◽  
Carbon Fiber ◽  
Ultrasonic Wave ◽  
Ultrasonic Transducer ◽  
Gravimetric Method ◽  
Ultrasonic Waves ◽  
Ultrasonic Wave Propagation ◽  
Out Of Plane ◽  
Set Up ◽  
Fiber Preforms

Out-of-plane permeability of reinforcement preforms is of crucial importance in the infusion of large and thick composite panels, but so far, there are no standard experimental methods for its determination. In this work, an experimental set-up for the measurement of unsaturated through thickness permeability based on the ultrasonic wave propagation in pulse echo mode is presented. A single ultrasonic transducer, working both as emitter and receiver of ultrasonic waves, was used to monitor the through thickness flow front during a vacuum assisted resin infusion experiment. The set-up was tested on three thick carbon fiber preforms, obtained by stacking thermal bonding of balanced or unidirectional plies either by automated fiber placement either by hand lay-up of unidirectional plies. The ultrasonic data were used to calculate unsaturated out-of-plane permeability using Darcy’s law. The permeability results were compared with saturated out-of-plane permeability, determined by a traditional gravimetric method, and validated by some analytical models. The results demonstrated the feasibility and potential of the proposed set-up for permeability measurements thanks to its noninvasive character and the one-side access.

In-situ cutting temperature and machining force measurements during conventional drilling of carbon fiber polymer composite laminates

2021 ◽  
pp. 002199832199807
Author(s):  
Sagar Kubher ◽  
Suhasini Gururaja ◽  
Redouane Zitoune
Keyword(s):  
Carbon Fiber ◽  
Tool Wear ◽  
Cutting Temperature ◽  
Spindle Speed ◽  
Machining Parameters ◽  
Micro Computed Tomography ◽  
Machining Forces ◽  
Drill Bits ◽  
Conventional Drilling

The evolution of in-situ cutting temperature and machining forces during conventional drilling of multi-directional carbon fiber reinforced polymer (MD-CFRP) laminates using a novel inverted drilling setup is presented. The in-situ cutting temperature was measured using fiber Bragg grating (FBG) optical sensor embedded in the stationary drill. The effect of machining parameters such as spindle speed and feed rate on the temperatures and machining forces were studied that indicate the predominant effect of spindle speed on machining temperatures. The drilled MD-CFRP samples and drill bits were characterized by scanning electron microscopy (SEM) and micro-computed tomography ([Formula: see text]) techniques to assess machining-induced damage in the samples and tool wear in the drill bits. Exit-ply delamination was observed in MD-CFRP samples that aggravates with increase in cutting temperature and thrust force caused by evolving tool wear. The measured in-situ machining temperatures using the current experimental setup can be used to achieve better machining models.

Phenomenological analysis of constrained in-plane compression of paperboard using micro-computed tomography Imaging

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Malte Wallmeier ◽  
Christophe Barbier ◽  
Felix Beckmann ◽  
August Brandberg ◽  
Claes Holmqvist ◽  
...  
Keyword(s):  
Compression Test ◽  
Large Deformations ◽  
Micro Computed Tomography ◽  
Computed Tomography Imaging ◽  
Porous Network ◽  
Out Of Plane ◽  
Plane Compression ◽  
Synchrotron Microtomography ◽  
Mechanisms Of Deformation

Abstract Large deformations under in-plane compression of paperboard appear in forming processes like hydroforming, pressforming and deep drawing, but the mechanisms of deformation have not been studied on a micromechanical level. A constrained in-plane compression test is presented. This test allows for in-plane compression, buckling, wrinkling and compaction. The constrained compression test is realized using a DEBEN CT-500 in-situ tester for laboratory microtomography and synchrotron microtomography. Experiments with five different materials spanning from laboratory handsheets to commercially available multi-layered paperboards are performed. Image processing is used to observe the local out-of-plane fiber orientation and compaction. A phenomenological investigation of the deformation behavior of these materials is presented. Delamination is found to be the primary mechanisms of failure in the multi-layered boards. Furthermore, a porous network structure, created by using long and minimally refined softwood fibers, is found to facilitate the formation of uniform wrinkles and compaction.

In situ investigation of the primary recrystallization of alpha titanium in HVEM

1978 ◽  
Vol 36 (1) ◽  
pp. 634-635
Author(s):  
S. Naka ◽  
R. Penelle ◽  
R. Valle
Keyword(s):  
Dimensional Analysis ◽  
Texture Evolution ◽  
Cold Work ◽  
Three Dimensional ◽  
Primary Recrystallization ◽  
Thin Foils ◽  
In Situ Investigation ◽  
Grain Growth Model ◽  
Alpha Titanium

The in situ experimentation technique in HVEM seems to be particularly suitable to clarify the processes involved in recrystallization. The material under investigation was unidirectionally cold-rolled titanium of commercial purity. The problem was approached in two different ways. The three-dimensional analysis of textures was used to describe the texture evolution during the primary recrystallization. Observations of bulk-annealed specimens or thin foils annealed in the microscope were also made in order to provide information concerning the mechanisms involved in the formation of new grains. In contrast to the already published work on titanium, this investigation takes into consideration different values of the cold-work ratio, the temperature and the annealing time.Two different models are commonly used to explain the recrystallization textures i.e. the selective grain growth model (Beck) or the oriented nucleation model (Burgers). The three-dimensional analysis of both the rolling and recrystallization textures was performed to identify the mechanismsl involved in the recrystallization of titanium.

Sign in / Sign up

Export Citation Format

Share Document