A novel tab for tensile testing of unidirectional thermoplastic composites

2017 ◽  
Vol 32 (1) ◽  
pp. 37-51 ◽  
Author(s):  
Mazlina Mohd Tahir ◽  
Wen-Xue Wang ◽  
Terutake Matsubara
Keyword(s):  
Stress Concentration ◽  
Composite Laminates ◽  
Tensile Testing ◽  
Sudden Change ◽  
Polyamide 6 ◽  
Thermoplastic Composite ◽  
Thermoplastic Composites ◽  
Static Tension ◽  
Simulation Results ◽  
Reduce Stress Concentration

This study proposes a novel tab for the tensile testing of unidirectional (UD) carbon fiber-reinforced thermoplastic polyamide 6 (CF/PA6) to reduce stress concentration at the tab end. The length of the new tab is identical to that of the UD CF/PA6 specimen to avoid a sudden change in geometry that is typically observed in a conventional tab end. Additionally, three types of UD CF/PA6 laminates from different manufacturers are used to fabricate tensile specimens. Specimens with a new tab and a conventional nontapered tab are tested under quasi-static tension. Finite element simulations of tensile testing are also performed for specimens with two types of tabs. The experimental and simulation results demonstrate that the newly designed tab reduces the stress concentration at the tab end by approximately 10% and improves the estimates of tensile strength for the UD thermoplastic composite laminates.

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.

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.

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.

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.

Research on Processing Technology of Polyester Fabric Reinforced Polypropylene Thermoplastic Laminated Composites

2011 ◽  
Vol 284-286 ◽  
pp. 373-376 ◽  
Author(s):  
Jia Horng Lin ◽  
Ching Wen Lin ◽  
Jin Mao Chen ◽  
Ting Ting Li ◽  
Ting Wei Chang ◽  
...  
Keyword(s):  
Polyethylene Terephthalate ◽  
Composite Laminates ◽  
Laminated Composites ◽  
Polyester Fabric ◽  
Processing Technology ◽  
Thermoplastic Composite ◽  
Thermoplastic Composites ◽  
Impact Properties ◽  
Impact Performance

Thermoplastic composites are eco-friendly to environment. In this study, PET/PP thermoplastic composite laminates were produced by interleaving polypropylene (PP) sheets with polyethylene terephthalate (PET) plain fabrics in the condition of varying thermocompression temperature, pressure and time. Afterwards, peel resistance, tensile and impact properties of PET/PP thermoplastic laminates were tested. And the tensile and impact performance of PET/PP laminates was respectively about 40 % and 320 % higher than PP laminates. It was shown that when thermal compressing under pressure of 40 Kg/cm2 at 230 °C for 0.5 minute, PET/PP thermoplastic laminates had optimum tensile and impact properties.

scholarly journals Fabrication of Knitted Glass Fibre Fabric Reinforced Thermoplastic Composite Laminates

1994 ◽  
Vol 3 (6) ◽  
pp. 096369359400300 ◽  
Author(s):  
S. Ramakrishna ◽  
H. Hamada ◽  
N.K. Cuong
Keyword(s):  
Tensile Properties ◽  
Glass Fibre ◽  
Composite Laminates ◽  
Thermoplastic Composite ◽  
Thermoplastic Composites ◽  
Knitted Fabric ◽  
Compression Moulding ◽  
Better Than

It has been shown that knitted fabric reinforced thermoplastic composites can be fabricated by compression moulding in two ways namely, film stacking method and co-knitted fabric method. The processability of co-knitted fabric method was better than the film stacking method. Tensile properties in the wale direction of the knitted fabric were higher than those of the course direction.

A numerical analysis of an energy directing method through friction heating during the ultrasonic welding of thermoplastic composites

2019 ◽  
Vol 33 (11) ◽  
pp. 1569-1587 ◽  
Author(s):  
Shahan Tutunjian ◽  
Oguzhan Eroglu ◽  
Martin Dannemann ◽  
Niels Modler ◽  
Fabian Fischer
Keyword(s):  
Composite Laminates ◽  
Microscopic Analysis ◽  
Thermoplastic Composite ◽  
Thermoplastic Composites ◽  
Vibration Energy ◽  
Additional Energy ◽  
Interfacial Layers ◽  
Spot Center ◽  
Friction Heating ◽  
A New Technique

The ultrasonic spot welding of fiber-reinforced thermoplastic laminates received a wide interest from researchers mainly in the fields of aerospace and automotive industries. This study investigated a new technique for focusing the ultrasonic vibration energy at the desired spot between two mating thermoplastic composite laminates. In this investigated method, no additional energy directing protrusions between the mating laminates were required to focus the vibration energy. It was found that by welding the laminates amid an ultrasonic horn and an anvil in which the prior had a larger contact surface with the laminate as the latter, it was possible to generate a localized friction heating. In the initial phase of the welding, the friction heating softened the interfacial layers and thus caused the focusing of the majority of the cyclic ultrasonic strain energy in the weld spot center. The assumption for the presence of the friction and its influence on the heat generation was investigated by means of finite element method (FEM) mechanical dynamic analysis. Microscopic analysis of the weld spot eventually delivered the proof for the melt initiation by friction at a ring around the weld spot and subsequent spot growth by viscoelastic heating.

Single-stream processing technique for in situ polymerization of glass fiber/polyamide-6 laminates

2016 ◽  
Vol 30 (12) ◽  
pp. 1639-1653 ◽  
Author(s):  
Peter W Barfknecht ◽  
Justin Martin ◽  
Brian Pillay ◽  
Uday K Vaidya ◽  
Gary M Gray
Keyword(s):  
Glass Fiber ◽  
Composite Laminates ◽  
In Situ Polymerization ◽  
Polyamide 6 ◽  
Processing Technique ◽  
Thermoplastic Composite ◽  
Polymerization Process ◽  
Single Stream ◽  
Monomer Solution

Ring-opening polymerization of anionic polyamide-6 (APA-6) requires both an activator and an initiator for the reaction to occur. Typical processing techniques for liquid-molded thermoplastic composite laminates involve infusion of the reinforcement with a premixed monomer solution containing both activator and initiator species. The technique described here is a step toward simplification and automation of the in situ polymerization process for composite laminates. By depositing the initiation functional group onto the reinforcement, infusion of a single stream of inert monomer solution is possible. The technique simplifies the processing equipment required and reduces the risk of contamination. Two separate methodologies derived from a silane and a diisocyanate were investigated. The soluble diisocyanate method was used to successfully demonstrate the single-stream APA-6 processing technique. Glass fiber surface-initiated polymerization was also demonstrated using the silane-derived initiator. The findings represent the first steps toward a new processing paradigm of APA-6 composites.

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