YIELD POINT AND STRESS RELAXATION BEHAVIOR OF PLY-PLY INTERACTION OF THERMOSET PREPREGS

2021 ◽  
Author(s):  
YUNPEI YANG ◽  
TARA FAHY ◽  
JONATHAN COLTON
Keyword(s):  
Plastic Deformation ◽  
Yield Point ◽  
Manufacturing Process ◽  
Complex Nature ◽  
Continuous Fiber ◽  
Lap Shear ◽  
Multi Stage ◽  
Lap Shear Test ◽  
Slip Deformation ◽  
Manufacturing Techniques

The forming of continuous-fiber composites is an automated manufacturing process capable of high production rates. Its greatest weakness lies in the tendency to develop wrinkle defects. The formation of wrinkle defects is the effect of a combination of multiple material deformation mechanisms. This paper investigates possible improvements for current manufacturing techniques by studying the interply properties of continuous-fiber thermoset prepreg. In this research, the inter-ply slip deformation behavior is tested via double lap shear tests. The results show that pressure, deformation rate, and moisture have a strong effect on the ply-ply interaction response. The multi-stage nature of the loaddisplacement response suggests the complex nature of the deformation. To better understand each stage of deformation, the total amount of slip deformation of the double lap shear test is measured. The total slip versus displacement profile indicates the presence of a yield point in the ply-ply interface. The yield point indicates both the softening of the ply-ply interface and the initiation of plastic deformation. The plastic deformation past the yield point can be further increased if the preform is held in a deformed state for some time before removing the external load. A new manufacturing process is proposed based on these results. One can take advantage of the yield point of the ply-ply interface and conform a preform onto an intermediate tool before conforming it onto the final tool. As deformation can be preserved once the material deforms past the yield point, this sequential forming approach can reduce the risk of wrinkling by reducing the slip required to complete the forming operation.

Characterization of FRP-to-concrete bonded interface Description of the single lap shear test

2009 ◽  
Vol 13 (9) ◽  
pp. 1073-1082
Author(s):  
Sylvain Chataigner ◽  
Jean-François Caron ◽  
Karim Benzarti ◽  
Marc Quiertant ◽  
Christophe Aubagnac
Keyword(s):  
Shear Test ◽  
Lap Shear ◽  
Bonded Interface ◽  
Lap Shear Test ◽  
Single Lap Shear Test

Design and development of novel reactive amine nanocontainers for a self-healing epoxy adhesive: self-repairing investigation using the lap shear test

RSC Advances ◽  
2015 ◽  
Vol 5 (27) ◽  
pp. 21023-21032 ◽  
Author(s):  
Sepideh Khoee ◽  
Zahra Kachoei
Keyword(s):  
Fracture Toughness ◽  
Shear Test ◽  
Epoxy Adhesive ◽  
Self Healing ◽  
Design And Development ◽  
Lap Shear ◽  
Lap Shear Test ◽  
P Recovery

Recovery of fracture toughness of a self-healing epoxy adhesive is achieved by using a novel amine nanocontainer.

scholarly journals Low-Cost Additive Manufacturing Techniques Applied to the Design of Planar Microwave Circuits by Fused Deposition Modeling

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 1946 ◽  
Author(s):  
Héctor García-Martínez ◽  
Ernesto Ávila-Navarro ◽  
Germán Torregrosa-Penalva ◽  
Alberto Rodríguez-Martínez ◽  
Carolina Blanco-Angulo ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Manufacturing Process ◽  
Fused Deposition Modeling ◽  
Low Cost ◽  
Microwave Frequency ◽  
Microwave Circuits ◽  
Fused Deposition ◽  
Microwave Electronic ◽  
Deposition Modeling ◽  
Manufacturing Techniques

This work presents a study on the implementation and manufacturing of low-cost microwave electronic circuits, made with additive manufacturing techniques using fused deposition modeling (FDM) technology. First, the manufacturing process of substrates with different filaments, using various options offered by additive techniques in the manufacture of 3D printing parts, is described. The implemented substrates are structurally analyzed by ultrasound techniques to verify the correct metallization and fabrication of the substrate, and the characterization of the electrical properties in the microwave frequency range of each filament is performed. Finally, standard and novel microwave filters in microstrip and stripline technology are implemented, making use of the possibilities offered by additive techniques in the manufacturing process. The designed devices were manufactured and measured with good results, which demonstrates the possibility of using low-cost 3D printers in the design process of planar microwave circuits.

Impact of manufacturing imperfections and surface defects on stress–strain behaviour of flexible adhesive joints

2020 ◽  
Vol 234 (5) ◽  
pp. 499-510
Author(s):  
P Liška ◽  
B Nečasová ◽  
J Šlanhof ◽  
P Schmid ◽  
V Motyčka
Keyword(s):  
Joint Strength ◽  
Surface Defects ◽  
Negative Impact ◽  
Deformation Behaviour ◽  
Adhesively Bonded ◽  
Adhesion Promoter ◽  
Premature Failure ◽  
Lap Shear ◽  
Manufacturing Techniques ◽  
Adhesively Bonded Joint

Precise adherence to the manufacturer’s instructions and requirements plays an important role in various installation processes. The presented paper deals with the evaluation of the effect of manufacturing imperfections and surface defects on the failure behaviour of flexible adhesive intended for façade application. The failure to comply with the accepted procedures is more common in construction practice than in other sectors of the industry, mostly due to the surrounding conditions and lack of trained supervision. Unfortunately, this may lead to premature failure of adhesively bonded joints and a considerable shortening of the service life of the entire construction. To determine the potential of the risk, five types of artificially applied (a) manufacturing imperfections: (1) application on wet adhesion promoter, (2) application after the expiry of the laying-time, (3) curing of samples at +1℃ (b) surface defects: (4) application on a wet substrate and (5) application on a dirty surface, were suggested. Moreover, the Taguchi L32 orthogonal array design was used to arrange the test setup of all possible combinations. The 1 K polyurethane adhesive was applied in tensile butt joints and single-lap shear joints composed of aluminium alloy and thermally modified wood substrates. The obtained results confirmed that non-observance of the required manufacturing techniques and recommended procedures can have a negative impact on the decrease of the adhesively bonded joint strength and deformation behaviour. Surprisingly, the most critical was not the combination of all suggested types of imperfections and defects. The performed one-way ANOVA revealed that the most perilous was the combination of types 2 and 4 in the tensile test with 77% joint strength reduction. In the shear test, the most critical was the combination of all types of imperfection and defects which led also to a 77% drop of shear strength.

Advanced Micro Shear Testing for Solder Alloy Using Direct Local Measurement

2003 ◽  
Author(s):  
Soonwook Kwon ◽  
Yuri Lee ◽  
Bongtae Han
Keyword(s):  
Fem Analysis ◽  
Test Configuration ◽  
Stress Studies ◽  
Lap Shear ◽  
Lap Shear Test ◽  
Geometrical Constraints ◽  
Accuracy Of Measurement ◽  
Electronic Assemblies ◽  
Auxiliary Device

A modified single lap shear test configuration, based on the Iosipescu geometry, is proposed for determination of the constitutive properties of solder alloys. An auxiliary device (extension unit) is introduced to improve the accuracy of measurement. The extension unit is attached directly to the specimen and it converts shear displacements to axial displacements, which are subsequently captured by a high-resolution extensometer. With aid of the extension unit, shear deformations are measured without compensating machine and grip compliance. The specimen configuration includes geometrical constraints at the solder/substrate interfaces in most electronic assemblies. Consequently, the results represent pseudo-continuum properties that take account for grain constraints at the solder/pad interface. They are properties that are more realistic for continuum mechanics based stress studies such as an FEM analysis.

scholarly journals Estimation of the Adhesion Interface Performance in Aluminum-PLA Joints by Thermographic Monitoring of the Material Extrusion Process

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3371 ◽  
Author(s):  
Stephan Bechtel ◽  
Mirko Meisberger ◽  
Samuel Klein ◽  
Tobias Heib ◽  
Steven Quirin ◽  
...  
Keyword(s):  
Substrate Temperature ◽  
Substrate Surface ◽  
Metal Structure ◽  
Extrusion Process ◽  
Scanning Calorimetry ◽  
Metal Base ◽  
Lap Shear ◽  
Lap Shear Test ◽  
Polymer Metal ◽  
Aluminum Substrates

Using additive manufacturing to generate a polymer–metal structure offers the potential to achieve a complex customized polymer structure joined to a metal base of high stiffness and strength. A tool to evaluate the generated interface during the process is of fundamental interest, as the sequential deposition of the polymer as well as temperature gradients within the substrate lead to local variations in adhesion depending on the local processing conditions. On preheated aluminum substrates, 0.3 and 0.6 mm high traces of polylactic acid (PLA) were deposited. Based on differential scanning calorimetry (DSC) and rheometry measurements, the substrate temperature was varied in between 150 and 200 °C to identify an optimized manufacturing process. Decreasing the layer height and increasing the substrate temperature promoted wetting and improved the adhesion interface performance as measured in a single lap shear test (up to 7 MPa). Thermographic monitoring was conducted at an angle of 25° with respect to the substrate surface and allowed a thermal evaluation of the process at any position on the substrate. Based on the thermographic information acquired during the first second after extrusion and the preset shape of the polymer trace, the resulting wetting and shear strength were estimated.

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