- 标题
- 摘要
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Ultraviolet Digital Image Correlation for Molten Thermoplastic Composites under Finite Strain
摘要： The thermostamping process used to fabricate thermoplastic prepreg composites is widely studied due to its use in several applications in the automotive and aerospace industries. In recent years, different constitutive mechanical models and new numerical techniques have been proposed to simulate this process. However, from an experimental point of view, no substantial progress has been recorded on the experimental methods used for the characterisation of thermostamped thermoplastic prepreg composites. Moreover, there is currently no experimental protocol to visualize or analyse deformation fields at temperatures above the melting point of a material during the characterisation process. The knowledge of these fields allows precision modelling of the mechanical behaviour of this type of material. Therefore, the aim of this paper is to propose a new experimental protocol that uses a digital image correlation method, which faces constraints such as light reflections on either the yarns or the molten thermoplastic matrix. The proposed solution uses an ultraviolet light source and a photoluminescent powder to make the speckle pattern. This approach avoids any visible reflections, since the sample itself is the visible light source.
关键词： Thermoplastic composite materials,Shear field measurement,Ultraviolet DIC,Bias extension test
更新于2025-09-19 17:15:36
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Investigation of the effects of femtosecond laser metal surface texturing on bonding of PA?6 to steel
摘要： This paper investigates the effects of femtosecond laser surface texturing on the interfacial bond strength of steel and a thermoplastic polymer PA?6 film. Ultimately the textures will be used for hybrids that are manufactured using a near-infrared (NIR) laser-assisted automated tape placement (ATP) process and carbon fibre / PA?6 composites, therefore the NIR absorptance of the textured metal substrate is also of interest. To identify the influence of different surface structures on the bonding strength, lap shear samples were manufactured with laser textures varying in pulse length, hatch distance and ablated depth and tested by ASTM D 3165. The surface structures were analysed with white light interferometry (WLI) and scanning electron microscopy (SEM). Additional optical measurements in the infrared radiation range of 900 nm to 1100 nm were executed with a spectrophotometer to evaluate the laser absorptance for the NIR automated tape placement process. The lap shear strength increased to the highest value of 31.9 MPa with a tooth shaped laser texture using a 275 fs laser pulse width, a hatch distance of 600 μm an ablated depth of 40 μm. Also the absorptance for this sample increased by approximately 13% to 73% compared to the unprocessed pickled steel.
关键词： interfacial bond strength,metal-composite hybrid,optical properties,thermoplastic composite,laser texturing
更新于2025-09-12 10:27:22