Early development and cost control of NVH performance

1. Challenges in NVH performance development

There are many challenges in NVH performance development, the most important of which are cost and development cycle.

In terms of cost saving, the overall automotive industry has been in a downturn in recent years, competition has become increasingly fierce, and the control of vehicle development costs has become increasingly strict; with the strict control of the cost target of each component, the NVH design plan requires more and more precision. Eliminating the waste caused by the redevelopment of molds and the rearrangement of process equipment caused by the late NVH rectification is of great significance to saving NVH development costs.

The NVH performance development process also faces periodic challenges: the vehicle development cycle continues to shorten, from 36 months to 24 months; the simulation analysis and optimization cycle in the detailed design stage is compressed; and the time for NVH problem troubleshooting and rectification in the ET to SOP actual vehicle stage is greatly reduced.

In order to cope with shorter cycle and lower cost vehicle development, the focus of NVH development work needs to be moved forward to the concept planning stage to reduce rework in the design and actual vehicle stages; improve the accuracy of NVH analysis and design solutions to achieve refined NVH development; establish and improve vehicle-level simulation analysis capabilities to accurately predict targets at an early stage.

2. Specific strategies and methods for NVH pre-development

Specific measures to advance NVH business

Design proposal: Before product design, consider the impact on NVH performance and make design suggestions to the product department on the selection, layout, size and space of the product structure as a reference for design;

Application stage: preliminary research

Design Proposal: Selection Proposal - Tire Model Parameter Selection

(1) Selection of tires with different aspect ratios

(2) The impact of different aspect ratios on tire vibration characteristics;

Design Proposal: Selection Proposal - Subframe Selection

The connection between the front and rear subframes and the body of the replacement model is rigid connection or flexible connection;

Identification of the impact of front and rear subframe connection on vehicle NVH performance; simulation or test

Analysis on the applicability of flexible and rigid solutions for front and rear subframes.

Design Proposal: Rear Suspension Tie Rod Arrangement

‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Table: Impact of different schemes on indicators

Table: Effects of different solutions on NVH performance

Design Proposal: Layout Proposal - Steering System Layout

Table: Simulation verification analysis

Design Proposal: Layout Proposal - Drive Shaft Angle Layout

For ordinary joint drive shaft, the sliding force starts to change suddenly when the included angle is greater than X degrees. Therefore, the included angle of the drive shaft needs to be controlled within X degrees, or a high-cost joint type, such as AAR joint type, should be used.

Figure: Impact of different solutions on indicators

Design Proposal: Layout Proposal - Intake System Layout

Concept simulation: Based on the basic vehicle and the ideas collected in the first version, complete the conceptual model and performance simulation verification of the design solution;

Application stage: design concept

Figure: Idle vibration concept simulation: Using the base vehicle body vibration as a boundary, the steering wheel vibration is simulated and the problem area is identified.

Figure: Concept simulation of road noise: using the deformed body of the base vehicle in conjunction with the chassis pre-research plan, road noise issues are identified and the effect of the initial version of the bushing is verified.

Figure: Conceptual simulation of medium and high frequency structural radiation noise: Taking the vibration of the motor and reducer test bench as the boundary, the chassis concept solution is used in conjunction with the basic vehicle body transmission test data to simulate the low-order structural radiation noise of the motor/reducer to evaluate the feasibility of the solution and its problems.

Figure: Concept simulation of acoustic package: Using the sound source of the base vehicle or benchmark as the boundary, the acoustic package objectives of the entire vehicle are decomposed into various systems, and the impact of different acoustic package solutions on system performance is verified to determine the final design solution.

Scheme inspection: inspect and confirm some fixed and essential design requirements and schemes;

Application stage: design concept, detailed design

SE: Simultaneous Engineering synchronous process;

Application stage (design discussion): design concept, detailed design

What is SE R&D? From the initial stage of R&D, all relevant departments participate and conduct discussions at the same time, so that all requirements of each department are implemented into the plan, without rework, and high-completion drawings are produced.

Simultaneous

Bench test: By analyzing and summarizing the bench and vehicle test data of the basic vehicle motor, motor reducer assembly, air compressor, water pump and other electrical components, the correlation between the bench and vehicle performance is established, and the bench NVH target of the design vehicle is formulated to control NVH problems at the bench stage;

Application stage: design concept and detailed design.

System optimization: Combining the excitation source and the response target requirements, the optimal design of the system or component design parameters is achieved through simulation analysis, which is different from the traditional simulation analysis of system and component NVH indicators;

Application stage: design concept, detailed design

Suspension bracket simulation optimization:

Vehicle response simulation: Build a vehicle simulation analysis model, input excitations such as road surface, powertrain, external flow field, analyze the responses of road noise, powertrain noise, wind noise, etc., analyze and predict the NVH level 1 target, and optimize the design parameters.

3. Summary

In order to improve the quality of NVH development and meet the needs of vehicle development with decreasing costs and shortened cycles, the continuous forward shift of the focus of NVH development is an important direction for future NVH work.

Establish the organization and process of early SE, input the NVH design requirements to the product design department at the conceptual stage as a reference for the detailed design of parts. It is necessary to establish the ability of NVH precise analysis and refined scheme design, establish and improve the vehicle-level simulation analysis ability, and accurately predict the achievement of NVH goals in the early stage of development. Only in this way can the quality of NVH development be improved, costs can be reduced, and cycles can be shortened.