## 5 Boom Configuration Optimization
### Optimization Approaches
#### 5.2.1 Heuristic Optimization Approach
If any changes were made, the updated configuration is stored as the first suggestion for the next boom configuration to be evaluated. Then, all possible combinations of more stable segments for the bottom and side, respectively, are generated and if the generated version is cheaper than the currently defined next configuration, the latter is replaced with the cheaper one. This is done to trade-off segment thickness and the number of stiffeners with regard to costs. Once the update is made for each segment at the bottom, side, and top, the boom configuration is evaluated with the structural analysis tool. This procedure is repeated until all buckling constraints as well as the constraints in Equations (11) and (14) are fulfilled. Afterward, the utilizations of stress and fatigue are checked again. If there are any violations, the procedure returns to Step 1, otherwise, it continues with Step 2b. In addition, in this step, it might be possible, due to the simultaneous changes, that the global optimum is missed out. However, similar to the argument in Step 1, the simultaneous changes are required to avoid run-time explosions. 2. Taking constraints of Equation (15) into account Recall that, thus far, due to the independent consideration of all segments, each segment could have different stiffener types. This is corrected now to fulfill the constraints of the same type of stiffeners for all bottom segments and all side segments. First, the currently used types on the bottom and side, respectively, are extracted from the segment configurations. Restricting the types of stiffeners to the already used ones, all more stable configurations are generated (one at a time for bottom and side, respectively). For each of these boom configurations, the utilizations of stress, fatigue, and buckling are calculated and, if all statics constraints are fulfilled, the costs are calculated. The cheapest of these configurations is used. If none of these configurations fulfills all statics constraints, the procedure returns to Step 1; otherwise, it continues with Step 3. (3). Optimizing for costs In the third step, thicknesses of segments are modified to minimize costs with regards to welding and material according to the objective function in Equation (4). To reduce the welding costs, starting from the base configuration handed over from Step 2b, the bottom/side/top segment thicknesses are successively and recursively increased, if possible, starting from the second segment, in order to be able to potentially save welding seams when combining segments to larger plates (in our case, combining up to three segments of the same thicknesses). First, for each bottom segment, starting from the second segment, it is checked whether the segment thicknesses can be increased to the next, the second next or third next higher thickness while keeping side and top segment configurations constant. Any resulting valid configuration is stored and additionally considered as starting configuration when looking at the following segments. In this way, first, variants of the bottom configuration are generated and the cheapest among those is taken, and similarly for the side and top segments. These three solutions are combined to form the cost-minimized boom and again evaluated with the structural analysis tool. If there is a violation in the structural utility constraints, the procedure returns to Step 1; otherwise, it terminates and outputs the final Boom Configuration.