2629 HH DELFT
Tel +31 15 711 26 30
Chamber of commerce nr 27280593
|Design & engineering: product development|
Our main competence is structural design and engineering, production and testing of (mainly) composite structures, or briefly: product development. We follow a standard procedure to develop a structural application (because we do not believe that hope is a method).
The project phases of this procedure are explained underneath and demonstrated by pictures from one of our projects: the development of a composite kart frame.
We start with defining the required functions of the structure that our client asks us to develop. In most cases the innovation is actually replacing a metal by a lighter material, mostly composites.
That leads to a specification of the loads (and combinations of loads) that the structure is subjected to.
Commonly the loads form part of a greater list of requirements (costs, weight, durability, operation et cetera) that have to be met. Loads and load safety factors are chosen in accordance with standards or in agreement with specifications of the client. However, sometimes the loads have to be investigated and specified themselves. We are able to deal with different kinds of loads that a structure can be subjected to: e.g. static loads, fatigue loads, dynamic or vibration loads and impact loads.
For composites it is necessary to establish and agree upon the material properties that are used in the structural design. The material properties are dependent on the materials (resin and fibres), the way of production, the environment and time.
Based on the loads that have to be transmitted and other requirements that have to be met a number of structural concepts or basic solutions are developed (concept generation).
These concepts are evaluated on design performance, production possibilities, estimated costs and the other requirements (evaluation).
Through mechanical reasoning and hand calculations the load transfer and the structural behaviour of the chosen concept(s) is elaborated. This enables a first dimensioning of the structure. On the basis of these first dimensionsa finite element (FE) analysis is performed. FE analyses are used to verify the behaviour of the structure and further specify the necessary dimensions of the structure.
One or more concepts are chosen for further elaboration (selection). Details of the structure (e.g. spots where concentrated loads are introduced) and joints of the modular parts out of which the structure is built up have to be designed and calculated. Often the joints and details are the limiting factors for the strength of the structure. In particular attention must be paid to joints of dissimilar materials (e.g. steel-composite joints). In daily practice most structures are hybrid or multimaterial applications!
Especially for composites it is important to involve production consequences into the design in an early stage because production may impose constraints, structurally as well as financially. Not only the way of production has to be clarified but also assembly and joints have to be considered. For big structures it is necessary to elaborate a modular production scheme. The modular parts out of which the structure has to be built up have to be defined and specified. Assembly and joining of the modular parts have to be elaborated. In the end a way of production, assembly and joining is chosen and described.
Structures, details or joints for which there are no commonly accepted design and calculation rules have to be submitted to tests in order to prove (trade-off) that they are able to withstand the loads they have been designed for. Because standards are often conservative, testing can also show how much reserve is present in the structure.
Feasibility study: weight and cost estimated
We carry out our engineering projects under the Standard Condition for Instructions given to Lightweight Structures B.V.