Characterization of shear stress at the tool‐part interface during autoclave processing of prepreg composites

Abstract

In this article, shear stress between an aluminum tool and a carbon fiber-epoxy prepreg is characterized during cure using polymeric release agent and release film at the tool-part interface. The effects of surface roughness, release materials, pull-out speed, temperature, and normal force (autoclave pressure) on the shear stress are investigated using a customized friction rig. Results show that the interfacial shear stress decreases as the temperature increases and it increases as the normal force increases when using either the release film or the release agent. Additionally, changes in surface roughness from 1.35 to 0.18 lm decrease the shear stress 10-27% while the use of release agent shows a decrease between 23% and 51% in the shear stress. Furthermore, strong adhesion between the tool and the part is observed when using release agent and pull-out speeds of 0.05 mm/min (static/dynamic friction ratio of 5.29 6 0.19). Using the experimental data, a mathematical approach based on the Coulomb's friction model is proposed to predict the friction force at the tool-part interface.

Examination of the metallization behaviour of an ABS surface

“…Thus, researchers are focused on the development of Ni lay-up tools via electrochemical methods since Ni has a rather mediocre CTE and is reliable under harsh environmental conditions [14]. Additionally, other important concerns about the tooling material are the thermal cycle durability and wear resistance [15]. Several studies related with the experimental investigation of the tool/part interface were conducted to determine durability and perform life cycle assessment [15][16][17][18].…”

“…Additionally, other important concerns about the tooling material are the thermal cycle durability and wear resistance [15]. Several studies related with the experimental investigation of the tool/part interface were conducted to determine durability and perform life cycle assessment [15][16][17][18]. Corresponding studies showed that Ni electroplating with sulphamate solution reveals lower damage to human health than four wellknown different thermal spraying processes (wirearc, plasma, high velocity oxygen fuel (HVOF) and cold spray) which is of signifance for manufacturers of aerospace platforms.…”

Tool-part interaction in composites microwave curing: Experimental investigation and analysis

“…Twigg et al 9,10 measured the interfacial shear stresses using strain gauges to analyze the tool-part shear interaction during composite processing. Joven et al 11 utilized a pull-out friction test rig to measure the shear stress between an aluminum tool and composites, and the different influence factors were studied. Ersoy et al 12 also employed a pull-out test device and the overlapping plies were pulled against each other at different rates in a servo-hydraulic testing machine.…”

A comparison of process-induced residual stresses and distortions in composite structures with different constitutive laws

“…In addition to the varying material properties, the tool-part interaction, moisture, fiber volume fraction gradients through thickness, composites compaction, and fiber wrinkle can also affect the residual stresses distortions. 8,24–29 It should be noted here that process-induced distortions in the composite structures are highly dependent on the material system due to potentially significant difference on material straining behavior in different states. 30,31 Prior to selecting a suitable constitutive law, the accurate characterization of material straining behavior is of equal importance.…”