“…Stage II maintains the body of water absorbed by the composite, tending to stabilize, which characterizes the Fickian behavior. 14,23 Figure 4.(a) Ratio of moisture absorption by exposure time and (b) typical Fickian moisture absorption curve.…”
Section: Resultsmentioning
confidence: 99%
“…In a more open structure, water can lodge in the interstices of the molecule structure, with higher diffusion rates in amorphous regions. 14 Such effects are facilitated or aggravated if the welding process does not result in good anchorage at the matrix/mesh interface, which promotes diffusion of moisture by defects, such as microcracks and pores.…”
Section: Resultsmentioning
confidence: 99%
“…The metallic mesh created a more fragile matrix/mesh interface which, together with the nature of the composite causes crack propagation in smaller stages where the propagation of cracks in different planes begins, 14 as indicated by the low presence of peaks in the graphs, especially in the graph of ENF in Figure 5(b). This interface can act as a path for the propagation of cracks arising from discontinuities in welded joints.…”
Section: Resultsmentioning
confidence: 99%
“…Upon reaching a stable weight, the samples were subjected to mechanical tests. 14 The test was performed according to ASTM D5229/D5229 M-04.…”
Section: Methodsmentioning
confidence: 99%
“…21 This technique characterizes variations in the glass transition temperature ( T g ) of the material that may have been caused by the welding process and/or environmental conditioning. 14 The analysis was performed on a DMA6100 device from SII Nanotechnology using the dual cantilever beam (flexing) mode with applied force of 2000 mN, frequency of 1 Hz, amplitude of 10 μm, and inert atmosphere of N 2 with flow of 100 mL min −1 , heating from 30°C to 250°C, with heating rate of 3°C min −1 . The sample sizes were 55 mm × 10 mm, with a maximum thickness of 3 mm.…”
This work aims to characterize the influence of hygrothermal conditioning on the mechanical and thermal behavior as well as the fractographic aspects of the interface of poly(ether imide) and glass fiber composite joints welded by electrical resistance using 400 mesh of AISI 304 stainless steel. The composites were mechanically characterized by Lap Shear Strength (LSS) and End Notched Flexure (ENF) testing to investigate maximum shear stress and energy from mode II interlaminar fracture toughness. Fractography was performed by SEM, while the influence on glass transition temperature and working temperature were evaluated by Dynamic-Mechanical Analysis and thermogravimetry. In the conditioned samples, the mechanical properties reduced 23% in the LSS test and 28% in the ENF test, while the fractography studies revealed elements of interlaminar and intralaminar fracture in both conditions. Thermal properties did not change significantly to disqualify this composite when applied to welding.
“…Stage II maintains the body of water absorbed by the composite, tending to stabilize, which characterizes the Fickian behavior. 14,23 Figure 4.(a) Ratio of moisture absorption by exposure time and (b) typical Fickian moisture absorption curve.…”
Section: Resultsmentioning
confidence: 99%
“…In a more open structure, water can lodge in the interstices of the molecule structure, with higher diffusion rates in amorphous regions. 14 Such effects are facilitated or aggravated if the welding process does not result in good anchorage at the matrix/mesh interface, which promotes diffusion of moisture by defects, such as microcracks and pores.…”
Section: Resultsmentioning
confidence: 99%
“…The metallic mesh created a more fragile matrix/mesh interface which, together with the nature of the composite causes crack propagation in smaller stages where the propagation of cracks in different planes begins, 14 as indicated by the low presence of peaks in the graphs, especially in the graph of ENF in Figure 5(b). This interface can act as a path for the propagation of cracks arising from discontinuities in welded joints.…”
Section: Resultsmentioning
confidence: 99%
“…Upon reaching a stable weight, the samples were subjected to mechanical tests. 14 The test was performed according to ASTM D5229/D5229 M-04.…”
Section: Methodsmentioning
confidence: 99%
“…21 This technique characterizes variations in the glass transition temperature ( T g ) of the material that may have been caused by the welding process and/or environmental conditioning. 14 The analysis was performed on a DMA6100 device from SII Nanotechnology using the dual cantilever beam (flexing) mode with applied force of 2000 mN, frequency of 1 Hz, amplitude of 10 μm, and inert atmosphere of N 2 with flow of 100 mL min −1 , heating from 30°C to 250°C, with heating rate of 3°C min −1 . The sample sizes were 55 mm × 10 mm, with a maximum thickness of 3 mm.…”
This work aims to characterize the influence of hygrothermal conditioning on the mechanical and thermal behavior as well as the fractographic aspects of the interface of poly(ether imide) and glass fiber composite joints welded by electrical resistance using 400 mesh of AISI 304 stainless steel. The composites were mechanically characterized by Lap Shear Strength (LSS) and End Notched Flexure (ENF) testing to investigate maximum shear stress and energy from mode II interlaminar fracture toughness. Fractography was performed by SEM, while the influence on glass transition temperature and working temperature were evaluated by Dynamic-Mechanical Analysis and thermogravimetry. In the conditioned samples, the mechanical properties reduced 23% in the LSS test and 28% in the ENF test, while the fractography studies revealed elements of interlaminar and intralaminar fracture in both conditions. Thermal properties did not change significantly to disqualify this composite when applied to welding.
Single lap shear specimens were manufactured using resistance welding of carbon fibre reinforced substrates by means of CNT web-based heating elements. Heating elements were manufactured by embedding the CNT web layers between layers of PEKK/glass fibre and connecting them to copper electrodes. An experimental campaign explored their electrothermal behaviour influencing the welding process. Single lap shear specimens were then welded at a pressure of 0.05 MPa and different levels of power and duration. An optimum bond was obtained with a specific power of 80–90 kW/m2 and a time of 150 s, achieving a shear strength of 30 MPa. Post-mortem analysis revealed that fracture propagated within the substrates. This work represents a further step in the integration of CNT web-based heating elements in an industrial welding process.
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