## 4 Simulation Study and Results
### Design and Execution of the Simulation Study  
The simulation study examines the causal relationships and intensities between the influencing factors and the production logistics target variables as a function of the assembly structure. Different product variants of a model helicopter from the institute's learning factory were used as an example for simulation applications. These product variants can be clearly distinguished by their assembly operations, a differing number of assembly operations and different processing times in their assembly operations. Before a simulation model could be set up in the material flow planning software Plant Simulation, Sections 3.2-3.4 submodels had to be applied to the sample application. The assembly operations of the different product variants are clearly described, and a corresponding assembly precedence matrix can be set up. The respective \(PUD_{i}\) of the assembly operations \(i\) could be calculated based on a forecast production programme. The hybrid value \(PUD_{hy}\) and the scaling factor \(k_{flex}\) are required as further control variables for the decision model. Both control variables were examined in the context of the simulation study using a partial factorial experimental plan. For each simulation scenario, the decision model had to be applied first to use its results for the dimension of the hybrid production structure as a planning basis for the simulation of different assembly configurations in Plant Simulation. In addition, further simplifying assumptions were integrated into the simulation model to reduce the influence of disturbance variables on investigating cause-and-effect relationships between input, control and target variables. These include the non-consideration of set-up and transport times and aspects such as disruptions, rework, employee performance fluctuations, and learning and forgetting behaviour. Likewise, optimal overall equipment effectiveness (OEE) is assumed, whereby no losses occur due to the availability, performance, or quality level. The products have a batch size of 1 and the production sequence should achieve an even utilisation of resources by applying the Heijunka cycle [36]. After initialising the simulation environment, the simulation study could be carried out with a partial factorial experimental plan over three investigation substudies. The simulation studies use the _ceteris paribus clause_ to analyse a correlation, assuming that only the observed control variable changes while all other systemic variables remain constant [37]. This should enable the derivation of mono-causal statements on the cause-and-effect relationships of the control variables. **Substudy 1:** Configurations are generated for different hybrid values \(PUD_{hy}\) using the decision model to examine the influence of this control variable on the performance of the hybrid, flow-oriented assembly organisation. The two extreme cases of hybrid value \(PUD_{hy}=0\) (flow line) and hybrid value \(PUD_{hy}=1\) (job shop) are examined, as well as hybrid values for the configuration of hybrid assembly organisations. For these configurations, hybrid values between 0.6 to 0.9 are examined in intervals of 0.1. **Substudy 2:** Different configurations were created with the decision model for different scaling factors \(k_{flex}\) to examine their influence as a control variable on the performance of the hybrid, flow-oriented assembly organisation. Scaling factors from 125% to 200% are examined in intervals of 25%. **Substudy 3:** Different configurations of the assembly organisation were created for a defined selection of the control variables. Modified production programmes were used in the simulation to examine the robustness of the organisation structure when deviations from the planning data were observed. In order to compare the production programmes, the factor \(C_{pp}\) was used as a measure of production programme complexity. A total of six different production programmes with increasing complexity were examined.