Void reduction of high-performance thermoplastic composites via oven vacuum bag processing

2017 ◽  
Vol 51 (30) ◽  
pp. 4219-4230 ◽  
Author(s):  
Danning Zhang ◽  
Dirk Heider ◽  
John W Gillespie
Keyword(s):  
Carbon Fiber ◽  
Composite Laminates ◽  
High Performance ◽  
Single Layer ◽  
Thermoplastic Composite ◽  
Thermoplastic Composites ◽  
Void Content ◽  
Plane Flow ◽  
Reduction Mechanisms ◽  
Air Diffusion

In this study, void reduction mechanisms during oven vacuum bag processing of high-performance carbon fiber thermoplastic composites are investigated. Entrapped air exists within the prepreg tape and between layers during lay-up and must be removed during processing to achieve aerospace quality (<1% void content) Key void reduction mechanisms during oven vacuum bag processing include through-thickness air diffusion and in-plane flow to the laminate edges through the permeable interlayer regions created by the prepreg surface roughness. Interlayer permeability between unidirectional and cross-ply laminates is measured experimentally and is sufficiently high for effective air removal during oven vacuum bag processing. Thick 72-layer carbon fiber/PEEK (poly (ether ether ketone)) laminates were fabricated with oven vacuum bag process under different edge sealing conditions. Void reduction in the laminate with sealed perimeter is dominated by air diffusion through the entire laminate thickness, and the laminate exhibits very high void content levels after oven vacuum bag processing. In the laminates with edges open to vacuum, air diffusion through a single layer and flow through the permeable interlayer lead to essentially void-free laminates. The findings show the importance of the interlayer permeability and edge conditions on the void reduction, and demonstrate that low void content can be achieved in thick section thermoplastic composite laminates via cost effective oven vacuum bag processing.

Experimental investigation on a fully thermoplastic composite subjected to repeated impacts

2019 ◽  
Vol 233 (19-20) ◽  
pp. 6985-7002
Author(s):  
S Boria ◽  
A Scattina ◽  
G Belingardi
Keyword(s):  
Composite Laminates ◽  
Mechanical Performance ◽  
Impact Damage ◽  
Energy Levels ◽  
Thermoplastic Composite ◽  
Thermoplastic Composites ◽  
Low Velocity ◽  
Repeated Impacts ◽  
Structural Parts ◽  
The Impact

In the last years, the spread of composite laminates into the engineering sectors was observed; the main reason lies in higher values of strength/weight and stiffness/weight ratios with respect to conventional materials. Firstly, the attention was focused on fibres reinforced with thermosetting matrix. Then, the necessity to move towards low density and recyclable solutions has implied the development of composites made with thermoplastic matrix. Even if the first application of thermoplastic composites can be found into no structural parts, the replacement of metallic structural parts with such material in areas potentially subjected to impact has become worthy of investigation. Depending on the field of application and on the design geometry, in fact, some components can be subjected to repeated impacts at localized sites either during fabrication, activities of routine maintenance or during service conditions. When composite material was adopted, even though the impact damage associated to the single impact event can be slight, the accumulation of the damage over time may seriously weaken the mechanical performance of the structure. In this overview, the capability of energy absorption of a new composite completely made of thermoplastic material was investigated. This material was able to combine two conflicting requirements: the recyclability and the lightweight. In particular, repeated impacts at low velocity, on self-reinforced laminates made of polypropylene (PP), were conducted by experimental drop dart tests. Repeated impacts up to the perforation or up to 40 times were performed. In the analysis, three different energy levels and three different values of the laminate thicknesses were considered in order to analyse the damage behaviour under various experimental configurations. A visual observation of the impacted specimens was done, in order to evaluate the damage progression. Moreover, the trend of the peak force interchanged between specimen and dart and the evolution of both the absorbed energy and of the bending stiffness with the impacts number were studied. The results pointed out that the maximum load and the stiffness of the specimens tended to grow increasing the number of the repeated impacts. Such trend is opposite compared to the previous results obtained by other researchers using thermosetting composites.

Damage detection of unidirectional carbon fiber–reinforced laminates with embedded magnetostrictive particulates: A preliminary study

2012 ◽  
Vol 24 (8) ◽  
pp. 991-1006 ◽  
Author(s):  
Oliver J Myers ◽  
George Currie ◽  
Jonathan Rudd ◽  
Dustin Spayde ◽  
Nydeia Wright Bolden
Keyword(s):  
Composite Materials ◽  
Carbon Fiber ◽  
Nondestructive Evaluation ◽  
Composite Laminates ◽  
Composite Structures ◽  
Single Layer ◽  
Polymeric Composite ◽  
Analytical Models ◽  
Fiber Reinforced ◽  
Carbon Fiber Reinforced

Defects in composite laminates are difficult to detect because of the conductive and paramagnetic properties of composite materials. Timely detection of defects in composite laminates can improve reliability. This research illustrates the preliminary analysis and detection of delaminations in carbon fiber laminate beams using a single layer of magnetostrictive particles and noncontacting concentric magnetic excitation and sensing coils. The baseline analytical models also begin to address the intrusive nature of the magnetostrictive particles as well as relate the applied excitation field with the stress and magnetic flux densities induced in the magnetostrictive layer. Numerical methods are used to begin to characterize the presence of magnetostrictive particles in the laminate and the behavior of the magnetostrictive particles in relationship to the magnetic field used during sensing. Unidirectional laminates with embedded delaminations are used for simulations and experimentations. A novel, yet simplified fabrication method is discussed to ensure consistent scanning and sensing capabilities. The nondestructive evaluation scanning experiments were conducted with various shapes and sizes of damages introduced into carbon fiber–reinforced polymeric composite structures. The results demonstrate high potential for magnetostrictive particles as a low-cost, noncontacting, and reliable sensor for nondestructive evaluation of composite materials.

Optical measurement of voids in situ during infusion of carbon reinforcements

2020 ◽  
pp. 002199832095982
Author(s):  
C Lystrup ◽  
A George ◽  
B Zobell ◽  
K Boster ◽  
C Childs ◽  
...  
Keyword(s):  
Image Analysis ◽  
Carbon Fiber ◽  
High Performance ◽  
Optical Measurement ◽  
Void Formation ◽  
Digital Camera ◽  
Void Content ◽  
Liquid Composite Molding ◽  
Automated Method

Liquid composite molding (LCM) is growing in importance as an alternative to traditional prepreg-autoclave methods for manufacture high-performance composites. The most significant roadblock to industry’s implementation of LCM is the usually higher void content compared with prepreg processing. One tool for reducing void levels in LCM involves optimization of flow velocity, which requires models to be developed to describe void formation at a given velocity. To help solve this problem, the following research illustrates the first known method for optical void measurement in situ during infusion in a carbon fiber reinforcement. Similar to previous studies on glass fiber, this work utilizes fluorescent dye and a digital camera to produce sufficient contrast and resolution for image analysis. Visible bubbles are photographed against the opaque carbon fiber background. An automated method of image analysis is outlined, which was used to analyze 230 images for three different flow orientations of a single fabric, producing the highest amount of experimental data seen so far on in situ void measurement. The resulting data identifies a minimum velocity threshold for minimal macro-void formation. The resultant void characterization framework will better enable optimization of LCM processing for high-performance composites based on carbon reinforcements.

Effect of Impregnation Process Parameters on the Mechanical Properties of Carbon Fabric Reinforced Thermoplastic Composites

2020 ◽  
Vol 858 ◽  
pp. 78-83
Author(s):  
Dae Won Kim ◽  
Jun Park ◽  
Chul Kyu Jin ◽  
Hyung Yoon Seo ◽  
Chung Gil Kang
Keyword(s):  
Mechanical Properties ◽  
Composite Material ◽  
Carbon Fiber ◽  
Process Parameters ◽  
Polymeric Materials ◽  
Thermoplastic Composite ◽  
Thermoplastic Composites ◽  
Body Parts ◽  
Carbon Fabric ◽  
Impregnation Process

Carbon fabric-reinforced thermoplastic (CFRP) composites, fortified with carbon fiber prepreg and epoxy base materials, have been mainly used for body parts for weight lightening, advanced high strength, and impact absorption In the current automotive industry However, as recycling of the composite material is required, attempts have been made to manufacture body parts using a thermoplastic polymeric material as a base substance. In order to produce various types of body parts by impregnating a liquid thermoplastic material into carbon fabric preform in methods of manufacturing a carbon fiber-reinforced thermoplastic composite material (CFRTP), it is important to understand the effect of the impregnation process parameters (time, temperature, pressing force) on the mechanical properties of the composite material. Therefore, in this study, the influence of impregnation process parameters on the mechanical properties of CFRTP is proposed. In addition, this paper presents the problems and solutions when polymeric materials are impregnated in carbon fabric.

Postprocessing method-induced mechanical properties of carbon fiber-reinforced thermoplastic composites

2020 ◽  
pp. 089270572094537
Author(s):  
Van-Tho Hoang ◽  
Bo-Seong Kwon ◽  
Jung-Won Sung ◽  
Hyeon-Seok Choe ◽  
Se-Woon Oh ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Carbon Fiber ◽  
Processing Parameters ◽  
Thermoplastic Composites ◽  
Void Content ◽  
Fiber Reinforced ◽  
Crystallinity Degree ◽  
Automated Fiber Placement ◽  
Carbon Fiber Reinforced

Promising carbon fiber-reinforced thermoplastic (CF/polyetherketoneketone (PEKK)) composites were fabricated by the state-of-the-art technology known as “Automated Fiber Placement.” The mechanical properties of CF/PEKK were evaluated for four different postprocessing methods: in situ consolidation, annealing, vacuum bag only (VBO), and hot press (HP). The evaluation was performed by narrowing down the relevant processing parameters (temperature and layup speed). Furthermore, the void content and crystallinity of CF/PEKK were measured to determine the effect of these postprocessing processes. The HP process resulted in the best quality with the highest interlaminar shear strength, highest crystallinity degree, and lowest void content. The second most effective method was VBO, and annealing also realized an improvement compared with in situ consolidation. The correlation between the postprocessing method and the void content and crystallinity degree was also discussed.

Manufacturing procedure to make flat thermoplastic composite laminates by automated fibre placement and their mechanical properties

2016 ◽  
Vol 30 (12) ◽  
pp. 1693-1712 ◽  
Author(s):  
Suong Van Hoa ◽  
Minh Duc Hoang ◽  
Jeff Simpson
Keyword(s):  
Mechanical Properties ◽  
Composite Laminates ◽  
Composite Structures ◽  
High Speed ◽  
Thermoplastic Composite ◽  
Thermoplastic Composites ◽  
Thermoset Composites ◽  
Material Deposition ◽  
Manufacturing Procedure ◽  
Composites Processing

Automated fibre placement (AFP) is a relatively new process for the manufacturing of composite structures. Among many attractive features, it provides high-speed of material deposition, more repeatability in terms of quality of the part, less labour intensive (as compared with traditional methods of manufacturing such as Hand Lay-Up), less waste and the ability to transition more seamlessly from design to manufacturing. AFP can be used to process both thermoset composites and thermoplastic composites. Thermoplastic composites processing holds many potential benefits. This is because if the process is done right in producing parts with good quality, it is fast since it does not require a second process such as curing in an autoclave or oven. For the purpose of comparison of performance and for design, it is necessary to determine the mechanical properties of laminates made using this process. However, there are challenges in making flat coupons for the purpose of testing for mechanical properties. This article presents these challenges and the procedure developed to make flat laminates using a simple AFP machine. Mechanical properties of these laminates are also determined and compared with those obtained from laminates made using conventional autoclave moulding.

Preparation of carbon fiber-reinforced polyimide composites via in situ induction heating

2016 ◽  
Vol 29 (9) ◽  
pp. 1027-1036 ◽  
Author(s):  
Chang Wei Liu ◽  
Chun Yan Qu ◽  
Lei Han ◽  
De Zhi Wang ◽  
Wan Bao Xiao ◽  
...  
Keyword(s):  
High Temperature ◽  
Carbon Fiber ◽  
Induction Heating ◽  
High Performance ◽  
Thermoplastic Composites ◽  
Heating Process ◽  
Current Field ◽  
Heating Method ◽  
Polyimide Composites

Induction heating, a direct and contactless heating method, is generally more rapid and energetically more efficient than other heating methods used. In this work, we report the high-temperature imidization of carbon fiber/polyimide (PI) composites using an in situ induction heating method. Furthermore, we compare the advantages of the method to a conventional thermal procedure. The formed composites feature almost identical imidization rates, glass transition temperatures, and thermal oxidative stabilities cured at the same heating temperatures using a different heating process. Upon doping with ferriferous oxide, the ability of the magnetic nanoparticles in an alternating current field was studied to further drive the heating process and increase the rising and cooling time. The in situ induction heating process proves to be a powerful method for the high-temperature polymerization of high-performance thermoplastic composites, particularly for a PI matrix.

scholarly journals Annealing Effects on the Crystallinity of Carbon Fiber-Reinforced Polyetheretherketone and Polyohenylene Laminate Composites Manufactured by Laser Automatic Tape Placement

2020 ◽  
Vol 26 (3) ◽  
pp. 308-316
Author(s):  
Svetlana RISTESKA ◽  
Anka T. PETKOSKA ◽  
Samoil SAMAK ◽  
Marian DRIENOVSKY
Keyword(s):  
Mechanical Properties ◽  
Composite Materials ◽  
Carbon Fiber ◽  
Processing Parameters ◽  
Polyphenylene Sulfide ◽  
Thermoplastic Composites ◽  
Void Content ◽  
Angle Of Incidence ◽  
Annealing Step

In situ consolidation of thermoplastic composites by Automated Tape Placement (ATP) is challenging. High quality ATP grade pre-preg material and tape head equipped with an efficient heat sources like lasers offer an opportunity towards high deposition rates and improved mechanical properties of composite materials. In this study uni-directional carbon fiber/ polyphenylene sulfide (UD tape prepreg CF/PPS), carbon fiber/polyetheretherketone (UD tape prepreg CF/PEEK) as well as blend of carbon fiber/polyetheretherketone/polyphenylene sulfide (UD tapes prepregs CF/PEEK/PPS) laminates are compared in terms of their properties after beeing processed by ATP technology. CF/PPS, CF/PEEK and blend CF/PPS/PEEK laminate specimens were processed using in-situ laser-assisted ATP (LATP) process. LATP processing parameters used in this study were chosen based on a preliminary trials; the results provide a basis for refinement of these parameters and prepreg material with an optimal and balanced set of final mechanical properties. This study showed an attempt how to manage the processing parameters for LATP process and to obtain composite materials with tailored properties. The process for production of thermoplastic plates with LATP head in general is a process that is governed by many parameters such as: laser power, angle of incidence, roller pressure and temperature, placement speed, tool temperature, then types of the roller material and the tool material. These parameters are not subject of discussing in this paper; they are kept constant, and the goal of the paper is to manage the crystallinity level within the composite thermoplastic material during annealing step at different temperatures after LATP process. Also, the void content during the production process could be controlled. More particularly, the authors showed that composites based on PPS matrix manufactured with LATP process possess higher flexural strength, with less void content compared to samples based on PEEK matrix. These samples showed also higher crystallinity after annealing step.

scholarly journals Fabrication of lightweight and high-strength carbon fiber-reinforced poly(ethylene-2,6-naphthalene) solid and foam composites

2020 ◽  
Vol 29 ◽  
pp. 2633366X2092255
Author(s):  
Yi-Fan Chen ◽  
Ying-Guo Zhou ◽  
Ming Huang
Keyword(s):  
Mechanical Properties ◽  
Carbon Fiber ◽  
High Performance ◽  
High Strength ◽  
Thermoplastic Composites ◽  
Reinforced Composites ◽  
Foaming Behavior ◽  
The Matrix ◽  
Poly Ethylene ◽  
Engineering Polymers

Poly(ethylene-2,6-naphthalene) (PEN) is one of the most important engineering polymers with high performance. However, the effects and foaming behavior of carbon fiber (CF)-reinforced PEN (CFRPEN) remain to be explored. In this study, PEN was used as the matrix for CF-reinforced composites, and its foaming behavior and mechanical properties were investigated. High mechanical properties can be evaluated through comparison with other similar CF-reinforced thermoplastic composites. A fabrication method to generate lightweight and high-strength CFRPEN composites is hence proposed.

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