E²F - Design and development of convertible folders


A central advantage of the folding design principle is that it combines two fundamental technical functionalities, namely that of changeability and that of induction of statically usable stiffness. By inserting folds, highly stressable structures can be produced from flat panels with a thin cross-section, which can also be modified if the folding edges are designed accordingly. A distinction is made between rigid folds as structural design principle for self-supporting lightweight constructions and variable folds as construction principle for movable structures. Both properties - reinforcement and changeability - predestine folding structures for applications in architecture and engineering.


ziele neu

Transformable folds create the link between architecture and mechanical engineering by combining the central aspects from a technical point of view of construction, statics and kinematics. The design and interpretation of such structures therefore requires the transfer of knowledge across traditional disciplinary boundaries, with the aim of facilitating the targeted technical use of transformable folds in architecture and civil engineering. A specific development process must be provided for this purpose.



The problems occurring in the development process must be identified and requirements for methods to be used must be defined. This is the only way to develop missing methods and tools. First of all, an overview of technically useful folding patterns and tasks to be performed is to be created. The first subobjectives are the respective classification as well as the mutual allocation of tasks and potential solutions. By means of the in-depth investigation of the applicable variable folds, the composition between typical properties and the use of these fold structures as construction or mechanical engineering constructions is discussed. The focus is on folding in the field of construction and related disciplines such as vehicle or plant construction, where influences on the folding process and the load-bearing behaviour have to be investigated.

Classification of convertible folds

Within the scope of market analyses and literature research, examples of changeable structures in technical applications are collected. Subsequently, by analysing commonalities and differences, characteristic features can be identified which are suitable for the uniform description and classification of folds. The focus of the work will be on folds of rigid, flexurally rigid surfaces with definite, non-negligible thicknesses. The systematic description and classification of folds is the prerequisite for the development of a specific development process. In order to guarantee a complete classification, changeable folding structures from mechanical engineering as well as architecture and construction have to be systematically recorded. In order to identify the characteristics, knowledge of geometry and tessellation as well as design and motion techniques is required.

Classification of possible tasks


Folding can be used to perform various tasks. This includes, among other things, the reduction of space requirements, e. g. for temporary pavilions, or the modification of the effective area, e. g. for facades that adapt to the time of day and climate situation. In addition to the pure purpose, tasks to be fulfilled can be distinguished according to other criteria, such as geometric or kinematic criteria. A systematic compilation and classification of the tasks that can be solved by folding is still missing. The identification of the existing tasks and the boundary conditions describing them leads to a systematic characterization of the respective task. Task classes are defined from the descriptions. In addition, possible new combinations of properties of the tasks are checked to show further classes of tasks and thus new areas of application for convolutions.

Analysis of specific technical problems in the development of variable folds


Many changeable folds have their origins in the art form Origami. The mobile models made of paper, a material with a negligible thickness, are able to absorb twists and strains during the course of the movement or to prevent them from arising in the first place. The folding structures considered in this project consist of rigid materials with a definite thickness. A particular challenge lies in the fact that the kinematic properties may change. A central task for the complex folding geometries is the detailed and joint training as well as the manufacturing processes and the assembly process. The aim is to gain systematic insights into the difficulties encountered in the development of changeable folding structures, which have so far only been used sporadically.

Assignment of specific problems to known development processes

spezifische probleme

Formulated development processes can be used for the structured approach and the methodical design of foldable structures. However, these do not take into account the special requirements of foldable structures, as they arise from the interaction between the different disciplines and the various fields of application. The compiled, specific problems of foldable structures are assigned to known development processes. Based on the classification, the most suitable development process is selected as the basis for a specific development process.

Formulation and verification of the specific development process

formulierungen neu

A specific, tailor-made development process supports the architects and engineers in all phases of a project. This is based on existing guidelines and processes from engineering and architecture. The development process is extended by further folding-specific boundary conditions and requirements. Clear definitions of the work steps and the respective interfaces should allow both a consistent and selective use of the process steps, and the specific process formulated in this way represents a hypothesis that has to be checked for applicability. A qualitative evaluation is carried out by means of concrete tasks and their processing in workshops. The results and feedback flow into process development.

Methods and tools for the development of convertible folder


In different engineering disciplines, various methods are available for individual steps of the development process and different aspects of the design. In addition to procedures for the determination of requirements, this includes catalogues for the selection of physical effects, methods for the measurement synthesis of mechanisms or analytical methods such as finite element and multi-body simulation. The suitability of these methods and associated tools for the efficient development and design of changeable structures will be investigated. It must be checked whether the functional scope of the corresponding tools is appropriate and at which specific questions and at which point in the development process they can be used effectively. This shows whether existing methods need to be adapted or new methods need to be developed in order to carry out the corresponding development steps.



Institute of Mechanism Theory, Machine Dynamics and Robotics

RWTH Aachen University

Eilfschornsteinstraße 18

52062 Aachen



Phone: +49 241 80 95546

Fax:      +49 241 80 92263


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