Abstract
The aim of this paper is to leverage the main surface topological descriptors to classify tape surface profiles, through the modelling of the evolution of the degree of intimate contact along the consolidation of pre-impregnated preforms associated to a composite forming process. It is well-known at an experimental level that the consolidation degree strongly depends on the surface characteristics (roughness). In particular, same process parameters applied to different surfaces produce very different degrees of intimate contact. It allows us to think that the surface topology plays an important role along this process. However, solving the physics-based models for simulating the roughness squeezing occurring at the tapes interface represents a computational effort incompatible with online process control purposes. An alternative approach consists of taking a population of different tapes, with different surfaces, and simulating the consolidation for evaluating for each one the progression of the degree of intimate contact –DIC– while compressing the heated tapes, until reaching its final value at the end of the compression. The final goal is creating a regression able to assign a final value of the DIC to any surface, enabling online process control. The main issue of such an approach is the rough surface description, that is, the most precise and compact way of describing it from some appropriate parameters easy to extract experimentally, to be included in the just referred regression. In the present paper we consider a novel, powerful and very promising technique based on the topological data analysis –TDA– that considers an adequate metrics to describe, compare and classify rough surfaces.
Highlights
Same process parameters applied to different surfaces produce very different degrees of intimate contact
Among composite forming processes for manufacturing structural parts based on the consolidation of pre-impregnated preforms, e.g., sheets, tapes, etc., the automated tape placement (ATP) appears as one of the most interesting techniques due to its versatility and its in-situ consolidation, avoiding the use of autoclave
Results we provide the numerical results and evaluations associated to each of the previously introduced models: Random Forest classification, k-means clustering, Code2Vect and Random Forest regression. 4.1
Summary
Among composite forming processes for manufacturing structural parts based on the consolidation of pre-impregnated preforms, e.g., sheets, tapes, etc., the automated tape placement (ATP) appears as one of the most interesting techniques due to its versatility and its in-situ consolidation, avoiding the use of autoclave. To obtain the cohesion of two thermoplastic layers two specific physical conditions are needed (a) an almost perfect contact (intimate contact) and (b) a temperature enabling molecular diffusion within the process time window, while avoiding thermal degradation. To reach this goal, a tape is placed and progressively bonded to the substrate consisting of the tapes previously laid-up. Intimate contact is required to promote the molecular diffusion In this process heat plays a double role, on one hand it enhances molecular mobility and on the other hand, the decrease of the material viscosity with the temperature increase, facilitates the squeeze flow of the heated asperities located on the ply surfaces under the compression applied by the consolidation roller
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