Automotive Buzz, Squeak and Rattle

Mechanisms, Analysis, Evaluation and Prevention

Martin Trapp, Fang Chen

• Editore: Butterworth-Heinemann
• Anno: 2011
• ISBN:
  9780080559117
• Argomento: Technologie et ingénierie
• Categoria: Transport et ingénierie de l'automobile

Buzz, squeak, and rattle (BSR) is the automotive industry term for the audible engineering challenges faced by all vehicle and component engineers. Minimizing BSR is of paramount importance when designing vehicle components and whole vehicle assemblies. This is the only book dedicated to the subject. It provides a self-contained reference to the background theory, testing, analysis, and elimination of BSR. Written for practicing engineers and industry researchers, the book has a strong focus on real-world applications making it an ideal handbook for those working in this important area. Chapters from leading experts from across the motor industry—with input from the design and research labs of Ford, Toyota, Daimler-Chrysler and GM—review the techniques available and provide readers with the appropriate physics, structural dynamics and materials science to address their own BSR issues.

• The only book available on automotive BSR (buzz, squeak and rattle)—the number one cause of complaint on new cars
• Comprehensive and authoritative, with contributions from leading figures in the field and companies such as Ford, Toyota and Daimler-Chrysler
• Enables readers to understand and utilize the complex tools used to assess, identify and rectify BSR in vehicle design and testing

Chapter 1. Overview on Vehicle Buzz, Squeak and Rattle

Frank Chen and Martin Trapp

Ford Motor Company

Chapter Outline

1.1. Customer Expectation and Vehicle Quality1

1.2. Buzz, Squeak and Rattle Mechanism5

1.3. Vehicle BSR Phenomena and Examples11

Body Interior – IP11

Example one: Tacoma IP/cross-car beam squeak12

Example two: 1997 Probe IP rattle/buzz (TSB/article #: 98-2-9)12

Body Closure – Doors and Liftgates13

Example one: 2004 Scion xB liftgate rattle (TSB #: NV008-03)13

Example two: Expedition window regulator squeak (TSB/article #: 98-17-21)14

Underbody BSR15

Transmission/Gear Rattle15

Example – 2001 Jeep wrangler gear rattle15

Seat Squeak and Seat Belt/Retractor Rattle16

1.4. Design Process16

1.5. Design Parameters and BSR Prevention17

Force Isolation18

Modal Separation18

Structural Rigidity18

Material Pair Compatibility19

1.6. Computer Aided Engineering (CAE)19

Manufacturing Process20

1.7. Conclusion20

References22

BSR may be the single largest factor that affects customers' perception of both vehicle initial quality and dependability. Vehicle dependability drives vehicle market share and residual value. Squeak generation requires that two contact surfaces have unstable and relative motion such as stick-slip motion. Buzz or rattle is produced by impact between two surfaces, either originally in contact or not. Most of the BSRs come from three major areas: IP, body closures, and underbody. BSR prevention is a system engineering process; the art is to achieve it with total cost effectiveness and durability. CAE may not render an absolute prediction if a design is subjected to yield BSR; however, it will provide the trend. It has become an indispensable tool for reducing product development time and cost. BSR prevention verification may be performed at the component, system or vehicle level. At the component or system level, usually a bench test can be performed with simulated load cases. At the vehicle level, it can be either a road test or using a hydraulic ride simulator with simulated road cases. Many BSR issues stem from the manufacturing process; SPC is often used to control assembly quality. Examples of the main technical papers and references are selected to illustrate BSR issues, which might shed some light on the state of the art.

1.1. Customer Expectation and Vehicle Quality

Vehicle noise may be roughly divided into two categories: the persistent type and the transient or come-and-go style. Persistent noise such as engine or road boom noise or wind noise will occur constantly during certain regular and wide-ranging operation conditions, and is often more annoying and discomforting to customers, and should be the first to be eliminated. With recent significant reductions in the persistent type of noise, the come-and-go kind of noise, including buzz, squeak and rattle (BSR), becomes more apparent and further needs to be eliminated to continuously improve vehicle quality [1], [2], [3], [4], [5], [6], [7], [8], [9], [10] and [11].

As discussed in reference 1, even as early as 1983 a market survey showed that squeak and rattle were already ranked the third highest customer concern for the three months in service (3MIS) period. In recent quality surveys, BSR was rated as the top quality issue including all original equipment manufacturers (OEMs – automobile makers) [2] and [3]. As Chance Parker, executive director of product and research analysis at JD Power and Associates, commented: “While the Initial Quality Study (IQS), which measures problems experienced in the first 90 days (3MIS) of ownership, can be an indicator of how models will perform over time, our studies consistently show that long term durability is a tremendously important factor to consumers. As the number of the problems owners experience with their vehicles increases, repurchase intent and the number of recommendations owners will make to others decreases.” The brands that perform better than the industry average vehicle dependability study (VDS) typically have $1000 more residual value than others that are below the average, according to JD Power and Associates [4] and [5]. VDS is surveyed every year for three-year-old models. An example is Ford, which made a significant improvement (on average, rectified nine faults) in its IQS from 2006 to 2008, as shown in Figure 1.1, which is modified to include most nameplates/brands and exclude luxury vehicles. Ford’s vehicle quality improvement in recent years has also been recognized by JD Power and Associates’ leading index and other leading vehicle quality research firms such as Consumer Reports, Strategic Vision, and Auto-Pacific. The 2008 JD Power and Associates’ Automotive Performance, Execution and Layout (APEAL) study showed that the Focus gained 88 index points over the last year. The Ford Escape also earned a spot among the top 10 most improved vehicles in the industry. In addition, five Ford Motor Company vehicles received second- or third-place honors in their segments. Strategic Vision put Ford neck-and-neck with Toyota for total quality, and ahead of everyone else. Ford has improved to 64% recommended vehicles from 54% in 2007 and 93% of Ford vehicles have average or better predicted reliability compared to last year’s 63% according to Consumer Reports. Part of Ford’s quality improvement is due to the reduction of BSR.

Figure 1.1 (a) Three years (2006/2007/2008) of JD Power and Associates Initial Quality Study on TGW. (b) Trend of JD Power and Associates IQS in the past three years for Ford, Toyota, Honda and Industrial Average.

Prospective customers may first consult various quality reports including Consumer Reports and JD Power and Associates’ quality study, and decide which vehicle they may want to evaluate before buying. If there is an indication that some nameplate vehicle has a low quality ranking, it may not be even on the consideration lists of prospective customers. Every year JD Power and Associates will issue the rankings in their vehicle Initial Quality Study (IQS).

When a prospective customer test drives a vehicle, if there is a BSR the customer will perceive the vehicle as low quality. If this can go wrong, then something else might go wrong later. It will not only affect the customer’s decision to buy this vehicle but may also project a negative image for the nameplate, brand or even for the manufacturer. The same effect holds or is even worse when a customer finds a BSR after purchasing. Since it is a come-and-go type noise, it usually takes s...