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.

Modeling and experimental investigation of out-of-plane deformation on mechanical performance of composites manufactured by ATL

2016 ◽  
Vol 36 (5) ◽  
pp. 347-359 ◽  
Author(s):  
Qiyi Chu ◽  
Yong Li ◽  
Jun Xiao ◽  
Dajun Huan ◽  
Xiaodong Chen
Keyword(s):  
Tensile Strength ◽  
Deformation Rate ◽  
Mechanical Performance ◽  
Plane Deformation ◽  
Experimental Results ◽  
Predicting Model ◽  
Fiber Waviness ◽  
Manufacturing Method ◽  
Four Point Bending ◽  
Out Of Plane

The change of mold normal curvature along the trajectory may result in out-of-plane waviness during the automated laying process, on which the layup speed and temperature would have an effect. A new parameter, deformation rate, was defined by combining the effect of mold curvature change rate and layup speed. A predicting model was proposed based on the fiber waviness and interlaminar sliding model to calculate the relationship between stiffness retention and the layup process parameters, including deformation rate and temperature. An experimental study on the effect of different deformation parameters on the tensile performance of composites was carried out based on a new manufacturing method of plated specimens with different levels of waviness by means of a four-point bending fixture. The experimental results showed that when the deformation temperature increases from 20℃ to 80℃, the tensile strength increases first and then decreases while the tensile module keeps increasing. While the deformation rate decreases from 0.40 to 0.04 mm−1/s, both tensile strength and module showed an increasing trend. The predicting model being validated by experimental results can be utilized to optimize the layup process parameter to satisfy the quality and efficiency requirements.

Enhanced Infrared Heating of Thermoplastic Composite Sheets for Thermoforming Processes

2021 ◽  
Vol 36 (1) ◽  
pp. 35-43
Author(s):  
M. Längauer ◽  
G. Zitzenbacher ◽  
C. Burgstaller ◽  
C. Hochenauer
Keyword(s):  
Steady State ◽  
Composite Materials ◽  
Mechanical Performance ◽  
Heating Time ◽  
Thermoplastic Composite ◽  
Infrared Heating ◽  
Thermoplastic Composites ◽  
Steady State Condition ◽  
Reflector System ◽  
Heating Station

Abstract Thermoforming of thermoplastic composites attracts increasing attention in the community due to the mechanical performance of these materials and their recyclability. Yet there are still difficulties concerning the uniformity of the heating and overheating of parts prior to forming. The need for higher energy efficiencies opens new opportunities for research in this field. This is why this study presents a novel experimental method to classify the efficiency of infrared heaters in combination with different thermoplastic composite materials. In order to evaluate this, different organic sheets are heated in a laboratory scale heating station until a steady state condition is reached. This station mimics the heating stage of an industrial composite thermoforming device and allows sheets to slide on top of the pre-heated radiator at a known distance. By applying thermodynamic balances, the efficiency of chosen parameters and setups is tested. The tests show that long heating times are required and the efficiency of the heating is low. Furthermore, the efficiency is strongly dependent on the distance of the heater to the sheet, the heater temperature and also the number of heating elements. Yet, using a full reflector system proves to have a huge effect and the heating time can be decreased by almost 50%.

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.

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

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.

Thermal Degradation of Flax Fibres as Potential Reinforcement in Thermoplastic Composites

2014 ◽  
Vol 894 ◽  
pp. 32-36 ◽  
Author(s):  
J. Chaishome ◽  
K.A. Brown ◽  
R. Brooks ◽  
M.J. Clifford
Keyword(s):  
Thermal Stability ◽  
Thermal Degradation ◽  
Heating Rate ◽  
Mechanical Performance ◽  
Failure Surface ◽  
Thermoplastic Composites ◽  
Infrared Spectrometry ◽  
Forming Process ◽  
Flax Fibres ◽  
Micro Structures

This work reports on a study of thermal degradation of flax fibres to gain an improved understanding of the use and limitations of flax fibres as reinforcement for thermoplastic composites manufactured by the vacuum forming process. The effect of heating on chemical decomposition and thermal stability was performed, using fourier transform infrared spectrometry (FTIR) and thermogravimetry (TG) techniques. In addition, the characterisation of micro structures of failure surface following tensile testing of the composites was conducted. The results show that the hemicelluloses decomposition of flax fibres during thermal degradation is a factor to have the detrimental effect on the thermal stability of fibres, particularly with low heating rate. The present investigation, A decrease of hemicellulose and pectin content of the fibres, a decrease of consolidation temperature and an increase of heating rate during the manufacturing of flax fibre thermoplastic composites should improve their mechanical performance.

The Effect of Infill Patterns and Annealing on Mechanical Properties of Additively Manufactured Thermoplastic Composites

2017 ◽  
Author(s):  
Sridher Rangisetty ◽  
Larry D. Peel
Keyword(s):  
Best Practices ◽  
Composite Structures ◽  
Fused Deposition Modeling ◽  
Mechanical Performance ◽  
Short Fiber ◽  
Thermoplastic Composite ◽  
Thermoplastic Composites ◽  
Limited Information ◽  
Fused Deposition ◽  
Reinforced Thermoplastics

Recently, carbon fiber-reinforced thermoplastics (CFRTPs) have become popular choices in desktop-based additive manufacturing, but there is limited information on their effective usage. In Fused Deposition Modeling (FDM), a structure is created by layers of extruded beads. The degree of bonding between beads, bead orientation, degree of interlayer bonding, type of infill and the type of material, determines overall mechanical performance. The presence of chopped fibers in thermoplastics increases melt viscosity, changes coefficients of thermal expansion, may have layer adhesion issues, and causes increased wear on nozzles, which makes FDM fabrication of thermoplastic composites somewhat different from neat thermoplastics. In the current work, best practices and the effect of annealing and infill patterns on the mechanical performance of FDM-fabricated composite parts were investigated. Materials included commercially available PLA, CF-PLA, ABS, CF-ABS, PETG, and CF-PETG. Two sets of ASTM D638 tensile and ASTM D790 flexural test specimens with 3 different infill patterns and each material were fabricated, one set annealed, and all tested. Anisotropic behavior was observed as a function of infill pattern. As expected, strength and stiffness were higher when the beads were oriented in the direction of the load, even for neat resins. All fiber-filled tensile results showed an increase in stiffness, but surprisingly, not in strength (likely due to very short fiber lengths). Tests of annealed specimens resulted in clear improvements in tensile strength, tensile stiffness and flexural strength for PLA, CF-PLA, and PETG, CF-PETG but a reduction in flexural stiffness. Also, annealing resulted in mixed improvements for ABS and CF-ABS and is only useful in certain infill patterns. This work also establishes ‘Best Practices’ of FDM-type fabrication of thermoplastic composite structures and documents the minimum critical fiber lengths and fiber fractions of several CF-filled FDM filaments.

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.

Influence of gripping method on tensile properties of unidirectional thermoplastic CFRP – Round-robin activity for international standardization in Japan

2019 ◽  
Vol 53 (28-30) ◽  
pp. 4161-4171
Author(s):  
Tsuyoshi Matsuo ◽  
Masaki Hojo ◽  
Kazuro Kageyama
Keyword(s):  
Tensile Strength ◽  
Mechanical Performance ◽  
Tensile Tests ◽  
Polyamide 6 ◽  
Round Robin ◽  
Thermoplastic Composite ◽  
Thermoplastic Composites ◽  
Round Robin Test ◽  
The Difference ◽  
Gripping Force

For unidirectional thermoplastic composite materials, it is preferable to use tab-less specimens in tensile tests owing to the low adhesive performance between specimens and tabs, as well as considerable warpage in laminates due to compression molding. In this study, round-robin tests are performed for unidirectional laminates in the 0° and 90° directions by two types of thermoplastic composites – carbon/polyamide 6 and carbon/polypropylene. The purpose of the round-robin test is to examine the difference between tab-bonded and tab-less specimens. Statistical analyses determined the degree to which tab-less specimens influenced their evaluation of the mechanical performance. In addition, from the detailed experiments, precisely controlled gripping force, fine roughness of grip surfaces, and a few inserted abrasive papers had significant impact on the 0° tensile strength of tab-less specimens. Based on the results, 0° tab-less strength of the proposed gripping method was shown to be almost equal to that of tab-bonded specimens recommended by the present tensile test standard.

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.

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