Effect of forming process on mechanical and interfacial properties for thermoplastic composite I-stiffened structures

2021 ◽  
pp. 095400832110515
Author(s):  
Guangming Dai ◽  
Lihua Zhan ◽  
Chenglong Guan ◽  
Minghui Huang
Keyword(s):  
Bonding Strength ◽  
Thermoplastic Composite ◽  
Thermoplastic Composites ◽  
Forming Process ◽  
Molding Process ◽  
Influencing Mechanism ◽  
Stiffened Structures ◽  
The Common ◽  
Polymer Aging

The forming process is the core factor to control the quality of thermoplastic composite components. In this paper, the common I-stiffened structures in the aerospace field were taken as the research object, and the forming process scheme was designed. Based on the prefabrication of C-shaped parts, the I-stiffened structures were prepared by the compression molding process. The influence law of molding temperature on the quality of the prefabricated C-shaped parts was explored. The time dependence of the PEEK melt viscosity was tested to provide the basis for the optimization of forming process parameters of I-stiffened structures. The influencing mechanism of thermoplastic composites repeatedly forming to the bonding strength of remelting interface was studied. The results show that repeated forming would lead to polymer aging and result in low bonding strength at the remelting interface of the I-stiffened structures. Optimizing the forming process could effectively reduce the aging of materials and improve the bonding strength of the remelting interface and overall mechanical properties of components. The research provides technical guidance for the manufacturing of complex thermoplastic composite components, especially the influence mechanism of the forming process on the bonding strength of remelting interface.

Conical Thermoplastic Composite Anisogrid Lattice Structure by Innovative Out-of-Autoclave Molding Process

2021 ◽  
Author(s):  
Fabrizio Quadrini ◽  
Daniele Santoro ◽  
Leandro Iorio ◽  
Loredana Santo
Keyword(s):  
Mechanical Performance ◽  
Lattice Structure ◽  
Glass Fibers ◽  
Density Measurement ◽  
Thermoplastic Composite ◽  
Molding Process ◽  
Conical Structure ◽  
Out Of Autoclave ◽  
Composite Lattice

Abstract A new manufacturing process for thermoplastic (TP) composite parts has been used to produce conical anisogrid composite lattice structure (ACLS). An out-of-autoclave (OOA) process has been prototyped by using the compaction exerted by a heat-shrink tube after its exposition to heat in oven. Narrow thermoplastic prepreg tapes have been wounded on a metallic conical patterned mold at room temperature; then, the conical structure has been inserted in the heat-shrink tube and heated. TP unidirectional prepreg tapes have been used with polypropylene matrix and glass fibers. After molding, the TP ACLS has been tested under axial and transverse compression. Conical adapters were used in the transverse loading condition to allow uniform application of the load. Density measurement has been also performed to assess the quality of the OOA process. Results of this study show that TP ACLS with complex shape may be produced with OOA solutions without affecting mechanical performance. In fact, porosity levels of the consolidate ACLS are comparable with the initial prepreg despite of the absence of vacuum during molding. Moreover, high compressive stiffness was measured along both directions without observing damages, buckling or cracks in multiple tests. In the future, this kind of technology could be used for larger ACLSs by substituting the heat-shrink tube with a narrow tape to be wound as well after lamination.

Effects of Technological Parameters on the Tensile Properties of GF/PET Hybrid Thermoplastic Composite

2011 ◽  
Vol 217-218 ◽  
pp. 1683-1688 ◽  
Author(s):  
Wei Tian ◽  
Yan Qing Li ◽  
Zhao Hang Feng ◽  
Cheng Yan Zhu
Keyword(s):  
Tensile Properties ◽  
Holding Time ◽  
Thermoplastic Composite ◽  
Thermoplastic Composites ◽  
Technological Parameters ◽  
Forming Process

The preforms were woven by the co-yarns which were consisted of GF, PP and PET. Then the co-yarns were manufactured into hybrid thermoplastic composites. The parameters of the forming process were studied by analyzing the tensile properties of the composites. The results show that the composite holds the best tensile properties when the pressure is 5MPa, the packing temperature is 190°C, and the holding time is 30 min. The existing of a second pressure of 10 MPa at 150°C for 3 min will help to improve the capacity of the load supporting for the GF/PET thermoplastic composites

On the Manufacturing Defects of Thermoplastic Carbon/Epoxy Composites Manufactured by Automated Tape Placement

2020 ◽  
Author(s):  
Tamer A. Sebaey ◽  
Noel O’Dowd
Keyword(s):  
Solidification Process ◽  
The Other ◽  
Thermoplastic Composite ◽  
Thermoplastic Composites ◽  
Circular Statistics ◽  
Engineering Practice ◽  
Manufacturing Defects ◽  
Thermoset Composites ◽  
Manufacturing Techniques

Abstract Thermoplastic composites are highly recommended for structural application, not only for their superior characteristics derived from the fiber and matrix materials but also for their recycling possibilities, which is a major issue in the today’s engineering practice. The manufacturing techniques for thermoplastics are different from those for the well-established thermoset composites. This paper addresses the quality of the thermoplastic composites by assessing the distribution of the fiber, the void contents and the waviness of the fibers, compared to the thermoset composites. IM7/PEEK and AS4/PA12 are the two thermoplastic composite systems used for this study, whereas, IM7/8552 is the thermoset composite used as reference. The specimens were examined using optical microscopy and computed tomography (CT) and the results were statistically treated using circular statistics. Compared to the IM7/8552 composite, the analysis reveals that the IM7/PEEK and AS4/PA12 composites, manufactured by ATP result in a higher volume of voids. On the other hand, ATP processing improves the alignment of the fibers, as the solidification process occurs while the fibers are in tension. The microscopy studies also show that the ATP manufactured composites have an area in between the different layers of tape with a low number of fibers, compared to the other areas.

scholarly journals A Study on the Influence of Hot Press Forming Process Parameters on Flexural Property of Glass/PP Based Thermoplastic Composites Using Box-Behnken Experimental Design

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
B. Senthil Kumar ◽  
Subramanian Balachandar
Keyword(s):  
Experimental Design ◽  
Process Parameters ◽  
Thermoplastic Composite ◽  
Thermoplastic Composites ◽  
Woven Composites ◽  
Flexural Property ◽  
Fibre Reinforcement ◽  
Forming Process ◽  
Compression Moulding ◽  
Structural Applications

A thermoplastic composite is produced from polypropylene matrix with glass fibre reinforcement. These types of composite materials are ecofriendly nature due to their reusability after their lifetime. These polymer composites are alternative to heavy metals that are currently being used in many non-structural applications. In spite of being ecofriendly nature, the range of applications is limited due to poor mechanical properties as compared with thermoset matrix composite. Hence an attempt was made in this work to improve the mechanical property such as flexural property of Glass/PP hybrid woven composites by optimizing the parameters during compression moulding, such as mould pressure, mould temperature, and holding time using Box-Behnken experimental design. Each process variables were taken in 3 different levels. Second order polynomial model with quadratic effect was chosen. The optimum combination of process parameters was obtained by using contour diagram. The levels of importance of process parameters on flexural properties were determined by using analysis of variance (ANOVA). The variation of flexural property with cited process parameters was mathematically modelled using the regression analysis.

Research on Process Optimization of Thin-Wall Plastics Injection Based on Moldflow and Orthogonal Experiment

2011 ◽  
Vol 399-401 ◽  
pp. 1646-1649 ◽  
Author(s):  
Fei Wang ◽  
Zai Liang Chen
Keyword(s):  
Orthogonal Experiment ◽  
Mold Temperature ◽  
Thin Wall ◽  
Molding Process ◽  
Melt Temperature ◽  
Pressure Time ◽  
Packing Pressure ◽  
Orthogonal Experiment Method ◽  
The Common

Warpage makes the plastic products deviate from the shape of the mold cavity that is one of the common weaknesses of plastics. In this paper, the melt temperature, mold temperature, packing pressure and holding pressure time are chosen as the study objects, and the use of Moldflow combined with orthogonal experiment method determine the best combination of molding process parameters to obtain the minimum warpage value, which improves the quality of injection products.

scholarly journals Influence of Automated Fiber Placement Parameters on Thermoplastic Composite Blanks Used on Stamp Forming Process

2021 ◽  
Author(s):  
Camille Vernejoux ◽  
Xavier Fischer ◽  
Simon Deseur ◽  
Emmanuel Duc
Keyword(s):  
Production Costs ◽  
Thermoplastic Composite ◽  
Thermoplastic Composites ◽  
Manufacturing Processes ◽  
Advanced Manufacturing ◽  
Forming Process ◽  
Fiber Placement ◽  
Automated Fiber Placement ◽  
Stamp Forming ◽  
Manufacturing Time

In recent years, advanced manufacturing processes have been developed to increase the speed of production in order to reduce production costs. At the scale of thermoplastic composites, the translation is the combination of advanced manufacturing processes. The focus in this study is more specifically on the coupling of automated lay-up (AFP) and stamp forming processes. To date, a consolidation process, such as press-consolidation of thermoplastic composites, obtained blanks. Several trials have begun using an automated fiber placement consolidation to reduce manufacturing time and use unidirectional material. However, the combination of AFP and stamp forming is useful if it optimizes this process without the blank’s full consolidation, which by resulting reduces the manufacturing time. This study estimates blank characteristics through thermal history imposed by a more rapid manufacturing process. A set of blanks with varying process parameters is produced to investigate the influence at the microscopic scale. The interface behaviour is observed with optical microscope and image processing. A statistical study applied to the process is carried out in order to relate the material observations to the input parameters. The results of this study are used for the study of the next process of the combination: the stamp forming.

scholarly journals Investigation of Press Forming Process for CF/PEEK and GF/PP Thermoplastic Composite Materials

2021 ◽  
Vol 2 (3) ◽  
Keyword(s):  
Composite Materials ◽  
Low Cost ◽  
Mechanical Tests ◽  
Sem Analysis ◽  
Thermoplastic Composite ◽  
Thermoplastic Composites ◽  
Forming Process ◽  
Crack Behavior ◽  
Press Forming ◽  
New Generation

Aerospace industry requires engineering materials with significant mechanical strength, low cost, easy to recycle, easy to process, and high chemical resistance. Thermoplastic composites are considered as new generation aerospace structural materials due to their superior characteristics. In this study, one of the most common methods used in manufacturing of thermoplastic composite parts from unidirectional (UD) pre-consolidated prepreg (blank), press forming process is investigated and crack behavior of the samples is examined. The forming process is utilized, and consolidated blanks of UD CF/PEEK and GF/PP composite materials are shaped by pressing, and mechanical tests are performed. Micro defects on the samples are monitored by microscopic examination and scanning electron microscopy (SEM) analysis. Results show that when the temperatures of CF/PEEK and GF/PP blank are increased by preheating, the formability of both composites are enhanced. Final outcomes reveal that both CF/PEEK and GF/PP composite materials can easily be used for possible aircraft structures. Additionally, CF/PEEK is found to be appropriate not only secondary structures but also for primary structures.

scholarly journals An experimental approach to reproduce in-plane fiber waviness in thermoplastic composites test coupons using a reverse forming method

2021 ◽  
pp. 002199832110267
Author(s):  
RDR Sitohang ◽  
WJB Grouve ◽  
LL Warnet ◽  
S Koussios ◽  
R Akkerman
Keyword(s):  
Experimental Approach ◽  
Mechanical Performance ◽  
Thermoplastic Composite ◽  
Thermoplastic Composites ◽  
Forming Process ◽  
Fiber Waviness ◽  
Manufacturing Method ◽  
Main Challenge ◽  
Defective Region ◽  
Bend Angles

In-plane fiber waviness is one of the defects that can occur from the stamp-forming process of thermoplastic composite (TPC) parts. The influence of this defect on the mechanical performance of multidirectional composites is not yet fully understood. The main challenge in determining the influence on mechanical properties lies in reproducing the waviness in test coupons that can subsequently be subjected to testing. This paper describes an experimental approach to reproduce representative in-plane waviness defects, specific for TPC, by reverse-forming of V-shape parts of various bend angles and inner radii. Characterization results show that this method enables the manufacturing of localized in-plane waviness in flat 24-ply quasi-isotropic C/PEEK composites with no voids. Furthermore, laminates having varying levels of maximum waviness angle ([Formula: see text]), between 14° to 64°, were successfully produced in this work. By comparing the [Formula: see text] value with the examples of industrial stamp-formed parts, it can be concluded that the developed coupon manufacturing method can reproduce waviness from TPC part production reasonably well. Finally, all of the produced laminates have defective region lengths smaller than 20 mm, localized within a predefined location which makes them well suited for standard compression test coupons.

The concept of motivation for effective credit risk management

2020 ◽  
Vol 26 (11) ◽  
pp. 2567-2593
Author(s):  
M.V. Pomazanov
Keyword(s):  
Risk Management ◽  
Economic Modeling ◽  
Type I ◽  
Credit Risk Management ◽  
Curve Modeling ◽  
Business Functions ◽  
The Common ◽  
Lending Decisions ◽  
The One

Subject. The study addresses the improvement of risk management efficiency and the quality of lending decisions made by banks. Objectives. The aim is to present the bank management with a fair algorithm for risk management motivation on the one hand, and the credit management (business) on the other hand. Within the framework of the common goal to maximize risk-adjusted income from loans, this algorithm will provide guidelines for ‘risk management’ and ‘business’ functions on how to improve individual and overall efficiency. Methods. The study employs the discriminant analysis, type I and II errors, Lorentz curve modeling, statistical analysis, economic modeling. Results. The paper offers a mechanism for assessing the quality of risk management decisions as opposed to (or in support of) decisions of the lending business when approving transactions. The mechanism rests on the approach of stating type I and II errors and the corresponding classical metric of the Gini coefficient. On the ‘business’ side, the mechanism monitors the improvement or deterioration of the indicator of changes in losses in comparison with the market average. Conclusions. The study substantiates the stimulating ‘rules of the game’ between the ‘business’ and ‘risk management’ to improve the efficiency of the entire business, to optimize interactions within the framework of internal competition. It presents mathematical tools to calculate corresponding indicators of the efficiency of internally competing entities.

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