Research on the Molding Design and Optimization of the Molding Process Parameters of the Automobile Trunk Trim Panel

In order to put forward the theoretical calculation formula for the compression force of the compression mold of the trunk trim panel, obtain the influence trend of the process parameters on the molding quality of the trunk trim panel, and obtain the optimal process parameters combination for the compression molding of the trunk trim panel, four process parameters, the heating temperature, time, compression pressure, and holding time, which affected the compression molding, were selected as the level factors; the maximum thinning rate, maximum thickening rate, and shrinkage rate of the trunk trim panel were selected as evaluation indicators and orthogonal experiments were designed and completed; the comprehensive weighted scoring method was used to obtain the comprehensive score results and obtain the comprehensive evaluation indicators of the best combination of process parameters of trunk trim panel; BP neural network and genetic algorithm were used to study the change trend of the evaluation indicators of trunk trim panel with the changes of process parameters; based on the optimal process parameter combination and the established neural network’s prediction function, the maximum thinning rate, maximum thickening rate, and shrinkage rate under a single process parameter change could be predicted, and the influence of a single process parameter on the maximum thinning rate, maximum thickening rate, and shrinkage rate could be obtained; the process parameters were optimized, and a maximum thinning rate of 28%, a maximum thickening rate of 4.3%, and a shrinkage rate of 0.8% were obtained; the optimal molding process parameters of the trunk trim panel were heating temperature of 209°C, heating time of 62 s, molding pressure of 14 kPa, and holding pressure time of 49 s; after optimization, the maximum shrinkage rate was 28.0880%, the maximum thickening rate was 44.3264%, and the shrinkage rate was 0.8901%; according to the optimal process parameters, the quality of the trunk trim panel was very good, which met the production quality requirements.

An in-Process Inspection System to Detect Noise Originating from within the Interior Trim Panels of Car Doors

Car body parts are sometimes responsible for irritating noise caused by assembly defects. Typically, various types of noise are known to originate from within the interior trim panels of car doors. This noise is considered to be an important factor that degrades the emotional satisfaction of the driver of the car. This research suggests an in-process inspection system consisting of an inspection workstation and a noise detection method. The inspection workstation presses down the car door trim panel by using a pneumatic pusher while microphones record the acoustic signals directly above the door trim panel and on the four sides of the workstation. The collected signals are analyzed by the proposed noise detection method after applying noise reduction. The noise detection method determines the presence of irritating noise by using noise source localization in combination with the time difference of arrival method and the relative signal strengths. The performance of the in-process noise detection system was evaluated by conducting experiments on faulty and healthy car door trim panels.

Exploration and optimization on the usage of micro-perforated panels as trim panels in commercial aircrafts

Micro-perforated panels (MPPs), as an alternative to porous materials for sound absorption, have been commonly used in electronic industries and aircraft engines but are barely used in aircraft cabins. The effect of MPPs on the sound insulation and absorption properties of aircraft cabin panels has been investigated in this article. Theoretical modeling has been conducted on an aircraft cabin panel structure with a trim panel replaced by an MPP trim panel, using the transfer matrix method and the classic MPP theory. It is indicated by the theoretical results that, although the sound transmission loss (STL) of the cabin panel with an MPP trim panel is lower than that with an un-perforated panel, the MPP trim panel can significantly enhance the sound absorption coefficient of the entire cabin panel structure. Based on the well-developed MPP theory, the sound absorption coefficient of an aircraft cabin panel with an MPP trim panel can be improved by optimizing the MPP's parameters at a specific frequency. Taking an engine frequency 273 Hz as an example, the optimization can increase the sound absorption coefficient to 1 by using the doublelayered MPPs. When the thermal acoustic insulation blanket is considered, although the STL of the proposed structure with double-layered MPP trim panels in a diffuse field is lower than those without MPP trim panels, the sound absorption in the cabin is significantly enhanced due to the double-layer MPP trim panel at the specific engine frequency and across all frequencies. The STL of the structure with double-layered MPP trim panels and TAIB can be higher than 40 dB from 880 Hz in a diffuse field, which implies its effectiveness as sound insulation structure in aviation industry. MPP trim panels provide a new idea for the design of aircraft cabin panels and areworthy of further research