Introduction
In conceiving this project in cooperation with AGC Plasma, our aim was to orchestrate a series of simulations through the lens of Ocean™, capturing the visual dynamics that define the optical behavior of coated fabrics – the interplay of light in both transmission and reflection.
The art of altering the essence of textiles or fibers has its roots in antiquity. In the textile landscape of the Neolithic era (6000 to 2000 BC), fabrics told tales of vibrant hues dyed with pigments extracted from nature. The Egyptians applied a wax-based alchemy to the sails of their linen vessels, rendering them impermeable to the ravages of water. In time, the advanced looms introduced new techniques for impregnating fabrics, giving rise to resilient floor coverings, protective umbrellas, and the like. The emergence of waxed or oiled fabrics (known as oilskin) gave textile fibers water-repellent properties for seafarers, a legacy that has now been inherited by the use of synthetic fabrics.
Our current simulation project, conducted with precision using Ocean™ for our client, focuses on this contemporary technique: Cold Plasma Coating, a form of PVD. In this process, ionized cold plasma acts as a carrier, applying the coating to the fabric. (Figure 1).
Figure 1 : Plasma assisted PVD principle.
This modern approach imparts various properties to the fabric, such as antimicrobial resistance, UV resistance, flame retardancy, and resistance to stains. For those interested in a deeper dive into surface modification through plasma treatment, the relevant information can be found in this article: “Study on Surface Properties of Polyamide 66 Using Atmospheric Glow-Like Discharge Plasma Treatment”.
The purpose of this project was to visualize the appearance of PVD coated fabrics on a tent in various lighting conditions.
3 Steps Workflow to simulate the optical behaviour of coated fabrics
1) Staging Geometry and Environment
A tent 3D model got created from scratch including various context elements (Figure 2). For computation purposes, the model was created from Rhino 3D modeler (see our technical documentation about Rhinoceros Plugins and Exporter).
Figure 2 : Tent 3D model.
The constraints of this Ocean™ simulation are closely linked to the optical properties of the material. Indeed, this type of fabric requires consideration in two different observation contexts: a daytime version to capture the reflective aspects with diverse reactions to light, and a nighttime version to comprehend semi-transparency, achieved through the inclusion of a light source embedded in the tent fabric.
The testing environments, encompassing night (Figure 3), cloudy day (Figure 4), and direct sunlight (Figure 5), are simulated using 360° HDR images (32 bits per pixel). These images encapsulate the luminous information essential for illuminating the scene.
2) Materials characterization of coated fabrics
The physically accurate simulation of this material type exploits the full potential of Ocean™. This simulation skilfully explore the nuances of complex phenomena, including both transmission (semi-transparency) and metallic reflection with angular dependence. Equipped with its spectral management capabilities for light information, Ocean™ excels at reproducing the sometimes counterintuitive behavior of complex and engineered materials.
Measurements of Bidirectional Reflectance Distribution Function (BRDF) and Bidirectional Transmittance Distribution Function (BTDF)have been instrumental in highlighting the optical characteristics.
The figure 6 displays the samples received for optical characterization. As a reference, a bare fabrics got provided (top left). The colors were obtained through the PVD treatment : gold (top right), dark blue (bottom left) and dark grey (bottom right).
Figure 6 : Physical samples of coated fabrics with various colors.
3) Optical behaviour Results
Considering both the various lighting and materials conditions, predictive images got calculated from Ocean™. The results are presented here below for the bare fabrics and the coated dark grey fabrics.
As depicted in Figures 7-9, the uncoated fabrics present a predominantly neutral color in daylight conditions, showcasing pronounced transmission characteristics in nighttime scenarios. By contrast, Figures 10-12 reveal that the dark grey coating imparts a robust metallic hue to the fabrics, demonstrating a compelling color transition from green to purple. Moreover, the coating significantly attenuates the transmission attributes of the fabrics, enhancing the privacy aspect of the tent.
Conclusion
In conclusion, the meticulous simulation of coated fabrics using Ocean™ has provided crucial insights into their optical behavior under varying lighting conditions. Visual assessments using HDR images in simulations showcased the dynamic responses of coated fabrics in night, cloudy day, and direct sunlight scenarios, illuminating shifts in color, transmission, and privacy aspects.
Figures 7-12 show the visual differences between uncoated and dark grey coated fabrics. The uncoated fabrics were neutral in colour during the day, with pronounced transmission at night, while the dark grey coating produced a striking metallic colour shift from green to purple. Most importantly, the coating significantly reduced fabric transmission, enhancing the privacy aspect of the tent. In essence, this simulation project underlines the key role of advanced tools such as Ocean™ in understanding the optical complexities of coated fabrics, providing a pathway for the development of functional and visually dynamic textiles in the field of materials science.
Going further: Using virtual prototypes for fabrics development
Fabric treatment techniques, such as impregnation, coating, and spraying, can significantly impact the optical properties of materials. Impregnation may alter light transmission by affecting the fabric’s density, while coating can introduce reflective properties, influencing color and sheen. Spraying allows for controlled modifications, impacting light interaction and appearance. These treatments collectively shape the optical behavior of fabrics, affecting characteristics like transparency, reflectivity, and color vibrancy, making them crucial considerations in designing materials for specific visual and functional outcomes.
OceanTM is proving key in predicting and simulating the impact of fabric treatments on optical properties. Its advanced simulation capabilities accurately model the interaction of light, allowing precise predictions of how impregnation, coating and spraying will visually alter materials. With the use of OceanTM, product designers can simulate the effects of these treatments on aspects such as transparency, reflectivity and color, gaining valuable insight into the optical complexities. This supports informed decision making and ensures that fabric designs are aligned with desired visual and functional outcomes prior to actual implementation, streamlining the development of innovative and effective textiles.
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