2
1 Introduction
As such, cabin monuments have to comply with strict legal airworthiness requirements
not only in terms of flammability but also mechanical strength [EAS17]. Acceptable
means of compliance include engineering evaluation for instance through calculation or
testing. Furthermore, in order to ensure that compliance can be substantiated, concurrent determination of the mechanical product properties is required throughout the
product development phase. Despite the fact that substantiation and concurrent analysis have seen increasing application of numerical analysis methods, time consuming and
costly physical testing remains extensive during cabin development projects. Of particular interest are detailed tests on sandwich panel joints since full scale structures typically
fail at these interfaces. In terms of airworthiness substantiation detailed tests programs
are extensive, since minor changes in the joint configuration (i.e. sandwich panel composition, adhesive type, material supplier or reinforcement geometry) can often only be
substantiated via testing. Analogously, concurrent mechanical analysis of design alternatives largely depends on physical tests. This is due to the complicated failure behavior
of sandwich panel joints with multiple simultaneous damage mechanisms, which makes
failure prediction via simulation challenging. However, virtual tests by means of simulation are desirable in order to reduce development time and cost, while increasing product quality due to front loading and predictive engineering.
1.2 Thesis objectives
This thesis intends to provide a hierarchical virtual testing approach, which enables the
prediction of the failure behavior and the strength of composite sandwich panels joints
by means of validated non-linear FE-simulations. The approach generally assumes that
there is an existing physical test which is to be replaced by simulation. It aims to provide
guidance on the definition of a suitable level of detail for the simulation model depending on the complexity of the failure behavior in the investigated test. In addition, the
approach outlines relevant hierarchy levels for the model development, while providing
a reference for test and simulation procedures within each level. In this context multiple
tests on sandwich structures along with the corresponding simulation models are suggested. Therefore, this thesis shall contribute material models and parameters for common sandwich materials in commercial aircraft cabins. The superordinate objective is to
enable the reduction of physical tests in the development phase of sandwich constructions.
1.3 Thesis structure
In chapter 2 the relevant theoretical background as well as state of the art concerning
virtual testing of sandwich structures is described. This includes an introduction to sandwich structures in general and in particular to the different aspects of sandwich panel
1 Introduction
As such, cabin monuments have to comply with strict legal airworthiness requirements
not only in terms of flammability but also mechanical strength [EAS17]. Acceptable
means of compliance include engineering evaluation for instance through calculation or
testing. Furthermore, in order to ensure that compliance can be substantiated, concurrent determination of the mechanical product properties is required throughout the
product development phase. Despite the fact that substantiation and concurrent analysis have seen increasing application of numerical analysis methods, time consuming and
costly physical testing remains extensive during cabin development projects. Of particular interest are detailed tests on sandwich panel joints since full scale structures typically
fail at these interfaces. In terms of airworthiness substantiation detailed tests programs
are extensive, since minor changes in the joint configuration (i.e. sandwich panel composition, adhesive type, material supplier or reinforcement geometry) can often only be
substantiated via testing. Analogously, concurrent mechanical analysis of design alternatives largely depends on physical tests. This is due to the complicated failure behavior
of sandwich panel joints with multiple simultaneous damage mechanisms, which makes
failure prediction via simulation challenging. However, virtual tests by means of simulation are desirable in order to reduce development time and cost, while increasing product quality due to front loading and predictive engineering.
1.2 Thesis objectives
This thesis intends to provide a hierarchical virtual testing approach, which enables the
prediction of the failure behavior and the strength of composite sandwich panels joints
by means of validated non-linear FE-simulations. The approach generally assumes that
there is an existing physical test which is to be replaced by simulation. It aims to provide
guidance on the definition of a suitable level of detail for the simulation model depending on the complexity of the failure behavior in the investigated test. In addition, the
approach outlines relevant hierarchy levels for the model development, while providing
a reference for test and simulation procedures within each level. In this context multiple
tests on sandwich structures along with the corresponding simulation models are suggested. Therefore, this thesis shall contribute material models and parameters for common sandwich materials in commercial aircraft cabins. The superordinate objective is to
enable the reduction of physical tests in the development phase of sandwich constructions.
1.3 Thesis structure
In chapter 2 the relevant theoretical background as well as state of the art concerning
virtual testing of sandwich structures is described. This includes an introduction to sandwich structures in general and in particular to the different aspects of sandwich panel