بهره‌گیری از الگوهای طبیعت برای طراحی ساختار‌های تغییرپذیر خم‌شو در معماری

به طور معمول بخش مهمی از تغییرات در معماری از طریق ساختار­های تغییرپذیر ممکن می­گردند. این گونه ساختارها عموماً از مصالحی سخت یا نرم یا ترکیبی از این­دو تشکیل شده­اند، اما توسعۀ مصالح جدید در عرصۀ معماری، امکان بهره­گیری از اجزای انعطاف­پذیر و خم­شو را نیز در سال­های اخیر فراهم نموده است. این گونه ساختارهای تغییرپذیر­خم­شو، برتری­هایی نسبت به ساختار­های تغییرپذیر معمول داشته که از مهم­ترین آنها سادگی، سبکی، نیاز به اجزای الحاقی کمتر و قابلیت بازگشت­پذیری ساده­تر به فرم اولیه می­باشد. نو بودن این­گونه سازه­ها باعث گردیده پاسخ به بسیاری از مسایل و سؤالات مربوط به آنها، مطالعه و پژوهش­های جدیدی را طلب کند که یکی از مهم­ترین این سؤالات به  مکانیزم­های مناسب برای تغییرپذیری آنها مربوط می­شود. در این مقاله سعی شده تا با رویکردی بایونیکی به یافتن پاسخ­هایی ملهم از طبیعت برای مکانیزم­های مولد تغییر فرم در این سازه­ها پرداخته­شود. در این مسیر با به­کارگیری فرایندی سلسله مراتبی و علمی، سعی به یافتن الگوهایی مناسب از طبیعت، استخراج ایده­ها از این الگو­ها و ارایۀ مثال­هایی عملکردی در معماری با ایده­های به­دست آمده شده است. در این مسیر دو روش برای انتقال قوانین طبیعت به معماری پیشنهاد گردیده که این روش­ها می­توانند در بسیاری از رویکردهای بایونیکی مشابه نیز استفاده داشته باشند.

Generally an important part of changes in architectural constructions are represented by convertible structures. These kinds of structures are composed typically of hard or soft materials or combination of both, which avoid independent structural deformations and need additional elements such as hinges, rollers or other similar components. Development of new construction materials like Fiber-Reinforced Plastic (FRP) provides new opportunities for application of pliable elements in new convertible structures. Deformation of these pliable elements is an active bending one. It means bending of these structures is influenced by residual stress in their load bearing capacity and behavior. In comparison to the traditional convertible structures, the application of these new materials deforms the structures with less or even no hinge or other additional elements. Other important advantages of these structures are: reversibility, simplicity and lightness. The novelty of these structures has caused some uncertainties and questions that should be solved through new research projects. The most important questions are related to the material properties, appropriate deformation mechanisms and shape variation capabilities of these pliable convertible structures. This paper represents a bionics approach for design of some new deformation mechanisms inspired by natural role models for these structures. Due to limited information about pliable structures, the first part of the paper introduces a background and basic information about these structures. Then the main reasons for development of pliable convertible structures will be represented. At the beginning of the main part of the paper the process sequences in biomimetic research (Bottom-up and Top-down process) are described. The technical problem about deformation mechanism of pliable convertible structures and its boundary conditions are defined at the first step of Top-down process sequence. In the second step seventh of best biological role models from our screening process between plants and animals in macro and micro scale are rendered. Two body deformations of the most promising biological role models are selected in the third step. Jellyfish and snapdragon (Antirrhinum majus) are the selected ones. Each one of these natural examples has particular mechanism principle for body deformation. Jellyfish moves through the water by radially expanding and contracting their umbrella. Muscles are used for the contraction of the body and expansion is by an elastic part of their body (mesoglea) which releases the energy stored from the contraction. But deformation of snapdragon caused by an external pressure. The bottom petal of snapdragon bends down by the pressure on both sides of it. This is caused by curved-line folding of this petal. In the fourth step of Top-down process the biological mechanisms are abstracted by two different methods. Body deformation mechanism of jellyfish is abstracted by geometrical models (abstract formal patterns) and petal deformation mechanism of snapdragon is abstracted by physical models (folded paper models). Abstracted biological principles with minor modification are applied in two architectural examples for pliable convertible structures in the final step. The technical prototyping, optimization, potential for implementation and industrial development are issues that need specialized research and practical examination and can be followed in the future trends.

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