Table of contents:
- Picture gallery
- Emission behavior of loudspeakers
- Fluid-structure interaction between housing and air
- Better understanding of the interactions
- Extremely resilient folding shower seats
- Reduced wall thickness with increased rigidity
- Optimized doors thanks to simulation
- Routine for new designs
Video: Simulation Makes You Fit For Everyday Life
The House of Simulation houses a wide variety of exhibits for everyday use. Interested trade fair visitors can use interactive displays to find out about the respective simulation history and learn more details from the simulation specialists from Cadfem present.
The companies participating in the exhibition stand include Biffar (front door), BSH household appliances (oven), Deckerform (chairs), Hansgrohe (shower head, thermostat), Head (tennis racket), Hewi (shower seat, support handle), KTM- Technologies (motorcycle), Miele (tumble dryer) and Vorwerk (Thermomix). In addition, calculations of speakers and car rims are shown. A wide range of information is available for each exhibit - why simulation was used in product development, what knowledge the calculations for the design of the product or the design of the manufacturing process provided and what benefits could be achieved with the simulation.
Here follows a small foretaste of the trade fair experience, the description of the simulation experiences of the companies Hewi and Biffar as well as the presentation of a simulation project for the design of loudspeakers.
Emission behavior of loudspeakers
An important quality characteristic of loudspeakers is the spatial radiation behavior. This is perceived as particularly good if the loudspeakers have characteristics that are as uniform as possible, namely over the entire frequency range that is to be covered. In order to achieve this, in addition to the acoustic propagation in the air, the interaction between the sound pressure waves, the membranes and the loudspeaker housing must also be taken into account. The aim of the simulation was to determine the influence of various factors such as the (resilient) housing walls or tolerances on the radiation behavior of the loudspeakers and the distortion of the emitted signal.
Additional information on the topic of the webinar: Intuitively from the installation space to the ideal CAD geometry
In conjunction with additive manufacturing processes, designers and product developers face new challenges, such as determining the optimal component topology. On May 16, you will learn how the Ansys simulation software and the Cadfem expert will support you. at 10:00 am using the example of live demonstrations. Register now for free at: www.konstructionspraxis.vogel.de/webinare
Fluid-structure interaction between housing and air
Ansys Mechanical was used to analyze the speaker's radiation characteristics. For this purpose, a fluid-structure interaction was defined between the housing and the surrounding air, with which the mutual influence can be depicted realistically. To ensure that the model size remains in manageable dimensions, only the relevant area of the surrounding air was taken into account in the simulation. Nevertheless, the sound was able to propagate unhindered due to the far field boundary conditions used. Based on the principle of equivalent sound sources, the necessary evaluations could also be carried out outside of the simulated model.
Better understanding of the interactions
The frequency-related parameterization of the network and the surrounding air reduced the computing times. A further acceleration could be achieved by the good parallelizability for the use of HPC (High Performance Computing).
The simulations led to a better understanding of the interactions between housing components and the surrounding air. On this basis, an efficient optimization of the loudspeaker's radiation behavior was possible without having to manufacture prototypes.
In addition, a higher information content was achieved compared to previous measurements with prototypes, since a "room-wide" analysis of sound propagation was possible and was not measured at individual points as with microphones. As a result, high product quality was achieved in a short time and with manageable costs.
Extremely resilient folding shower seats
Especially in hospitals, nursing homes or senior residences - but also in private apartments - simple solutions for complex requirements are required. Among other things, Hewi develops innovative products for these areas, such as the Hewi 950 series folding shower seat. Hewi's shower seats must be designed so that they do not exceed the limits of deformation, strength and force on the wall bracket, even under extreme loads, and with the highest demands on aesthetic design.
Reduced wall thickness with increased rigidity
For the original design of the shower seat, which was relatively solid, a glass fiber content in the plastic of at least 30% was determined according to the first calculations, so that the desired strength and rigidity could be achieved. The Ansys simulation software was used to investigate how the selected material behaves, where the critical areas of the loads are and where material can be saved.
Since thinner components are easier to manufacture during injection molding - with fewer sink marks, more homogeneous cooling and thus less warpage and internal stresses - a special polyamide with 50% glass fiber was ultimately chosen. This made it possible to significantly reduce the wall thickness of the seat surface and at the same time increase the rigidity, with the glass fibers being oriented according to the highest loads during injection molding. By increasing the glass fiber content to 50%, less material was required. The weight was reduced by almost 30% to around four kilograms.
Optimized doors thanks to simulation
For Biffar doors, among other things, the focus was on thermal insulation and burglar resistance and were examined with the support of Fraunhofer ITWM and improved according to the calculation results. The thermal insulation properties in construction are characterized by the U-value (heat transfer coefficient), which in the case of door construction is made up of the U-values of the door leaf, door frame and frame. The door leaf has the largest area and therefore has the greatest influence.
However, the heat transport within the framework of the overall balance of energy efficiency should not be neglected. When simulating heat transport, in addition to heat conduction in the solid bodies involved, convective effects and heat radiation, for example in hollow profiles, must also be taken into account. Although the thickness of the frame and the amount of material used were hardly increased, a significantly lower U-value could be achieved with a variant optimized by simulations.
Routine for new designs
The results of standard FEM simulations for stress analysis were used to assess burglar resistance and wind load. The burglar resistance is examined on the basis of local pressure loads on different points on the door surface. This means that both the materials and the wall thicknesses can be optimized, whereby it should be noted that lighter doors are advantageous both during assembly and with regard to their function when opening and closing.
The simulation results presented here were confirmed in real tests and tests with high accuracy. In addition, such an optimization of doors and frames would not have been possible in such a short time without FEM simulations. This convinced the people in charge at Biffar that simulation has quickly become routine with new door designs.
Hands-on simulation at the Hannover Messe 2017
The benefits of simulations, which were shown here using three application examples, can be transferred to many other product developments from a wide variety of manufacturers. More examples to touch with the corresponding simulation stories will be presented at the Hanover Fair, where the simulation experts from Cadfem are available for detailed information. (Mz)
Hannover Messe: Hall 6, Stand K50
* Dipl.-Ing. (FH) Christof Gebhardt is Head of Business Development at CADFEM.
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