Core Competence
Optimization of Gear Acoustics and Dynamics


A major quality criterion of a gear transmission is the resulting noise behavior in the application. In the conception phase of the gear set-up, the first decisions regarding the noise behavior need to be made. Finally, in the micro geometry design, not only the load caused deformations of the housing and shaft-bearing system but also the tolerances of the gear manufacturing and assembly need to be taken into account.

The gear department of the WZL analyzes the noise behavior starting from the design process, to the manufacturing and assembly of the gears, to the final operating behavior on the test rig or in application. Thereby, manufacturing related production characteristics are already considered in the design phase and result in a robust gear design. The necessary expertise, software tools and test rigs are the result of close exchange with partners from the gear industry and long-term research work in the area of gear acoustics.

The noise behavior of gears is described by the basic excitation mechanisms of the parameter, path and impulse excitation. The complex cause-effect relationship is influenced by the design, the manufacturing and the operating loads. The gear excitation is transferred via the dynamic system along the transmission path and is finally emitted as airborne noise. For ambitious noise topics, an advanced level of expertise as well as validated analysis tools is necessary.

The investigation methods for the analysis of the noise behavior of gears include the dynamic noise testing, contact pattern tests and quasi-static single flank testing. The WZL has two and three engine test rigs with various power ranges for the investigation of the noise behavior of gears in the original application or in specialized gear test fixtures which can be adjusted to customer needs. For airborne noise analysis the universal gear test rig provides an anechoic chamber certified according to DIN ISO 3744 accuracy class 2. With theses test rigs special scenarios such as simulation of combustion engine excitation, driving along curves (differential gears) or high speed applications can be investigated. As rotary measurands for acoustic evaluation the transmission error or the rotary acceleration at the input and output are evaluated. Furthermore, structure-borne noise can be measured at certain positions on the gear housing. The analysis and optimization tools are developed at the WZL and consist of validated FE-based tooth contact analysis in combination with multi body simulations (MBS) as the force-coupling element for the simulation of the dynamic excitation behavior. By using psychoacoustic metrics an aural-compatible evaluation of the vibro-acoustic characteristics of gears is possible.

The objective: Individual solutions
- Analysis of noise excitation behavior of gears by means of topography measurement, validated tooth contact analysis and transmission error measurement technology
- Design of excitation optimized gears considering manufacturing tolerances
- Analysis of the dynamic excitation behavior of gears via dynamic simulation and angular acceleration measurement technology
- Psycho-acoustic noise evaluation of gears
- Consulting and root cause analysis for noise issues in gear production
- Flexible test rig investigations on universal test rigs in a certified anechoic chamber for noise characterization of transmissions
- Multiple sensors and multi-channel DAQ equipment for noise measurement
- Gear test fixtures for the evaluation of quality and design of cylinder, bevel, beveloid and planetary gears


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