No area of the third-generation Tucson crossover utility vehicle was left untouched by Hyundai engineers, but particular attention was placed on re-engineering the chassis for improved ride and handling, and importantly, better NVH (noise, vibration, and harshness) characteristics.
Not surprisingly, the 2016 Tucson platform is larger than the previous generation’s; however, engineers focused on improving width and wheelbase for greater ride comfort and linear stability, according to Mike O’Brien, Vice President, Corporate and Product Planning, Hyundai Motor America (HMA).
“We have a full lineup of CUVs, so having the biggest one in the segment is not the best because people that buy in this area of the market focus more on maneuverability and parking,” O’Brien said. “So instead we focused on getting the best width that we could, at 72.8 in, and also the best wheelbase at 105.1 in, which gives a sense of stability.”
Compared to the 2015 model, the new Tucson is 1.1 in (27.9 mm) wider, with a 1.2-in (30.5-mm) increase in wheelbase. The front and rear overhangs were increased “in smaller proportion,” centering more of the Tucson’s mass within the wheelbase for better handling response and control. The CUV is 3 in (76 mm) longer overall than the outgoing model, at 176.2 in (4475 mm).
To enable the suspension refinements to be more effective, Hyundai engineers focused on increased use of advanced high-strength steels (AHSSs) and what O’Brien called “advanced aerospace-based, high-strength adhesives.” The entire Tucson body and chassis is more rigid, using 51% AHSS—greater than 60 kg/mm2 (590 MPa)—compared with 18% for the former model.
“Another thing that we’ve done, very similar to what we did with Genesis, is to use a tremendous amount of high-strength adhesives,” said O’Brien. “We went from no adhesives—just a welded structure on our outgoing model—to now over a football field in length of adhesives [335 ft (102 m), to be exact]. Not only does this help in body strength, but also in NVH by isolating noise better than just welding.”
The result of such efforts is a 48% improvement in body rigidity.
‘World first’ mounting structure
One area that benefits from the employment of AHSS is a “world’s first” shock-absorber mounting structure for the 2016 Tucson. The CUV employs a dual-reinforcing panel rear wheelhouse design, which optimizes panels that are prone to vibration, resulting in a 109% increase in rigidity, reduced road noise levels, and ride and handling improvements. Traditional designs employ only one reinforcement.
“Hot-stamped steel is the highest stiffness steel we use. Generally it is used for crash [protection], but we also use it for the [integrated dual-member rear wheelhouse] structure,” said Chahe Apelian, Senior Manager of Vehicle Evaluation – Chassis & NVH, Hyundai America Technical Center, Inc., as he gave Automotive Engineering a walk-around of the Tucson body-in-white (BIW) cutaway.
“In terms of the rear suspension towers, it’s to make the attachments stiff enough to where we increase the envelope of tunability of the shock absorbers,” he continued. “Once the body becomes stiff to the point where it deflects very little, all the energy from the road is absorbed by the shock absorber and that’s a tunable variable.”
Apelian pointed out the spring seat on the underside of the BIW wheel well, comprised of 100 kg/mm2 (980 MPa) HSS and hot-stamped steel; “on the other side, we sandwich it with another piece of hot-stamped steel, so it’s all bracketed in and takes all the forces right here.”
Engineers in Korea began working on the solution since the previous generation, according to Apelian, after identifying the rear suspension mount as an area that needed improvement. HSS being a “core technology” for Hyundai, its employment for this application made sense, he said.
“The part sizes aren’t very big; it’s not like we’re using a whole rocker,” he explained. “It’s a laser-focused application, so it minimizes cost but gives us the biggest bang for the buck…You could do it with normal steel, but then you start adding more weight.”
Though the overall solution is heavier than the previous single reinforcement, Apelian noted that “all of the other solutions would be higher weight…to achieve this much stiffness and this much ride improvement.”
Other NVH enhancements
Another area targeted for NVH improvements was the subframes, which are fully isolated, front and rear. “The platform is basically a derivative of the Sonata platform, and we carried over those,” he said. “The body stiffness is critical to making sure those subframes work, so that the handling doesn’t degrade, and also for managing the 19-in tires, making sure they work with the whole system.”
The 19-in tires are one size larger than the previous-generation’s available 18-in tires.
Front suspension is a MacPherson strut design, with coil springs, gas-filled shock absorbers, and a 24.7-mm (0.97-in) stabilizer bar. The rear suspension is an independent, multi-link design, now with dual lower arms for both front-wheel and all-wheel-drive models, for optimal ride comfort and body control. Overall, front and rear suspension setups are now 20% stiffer than the outgoing Tucson’s.
Suspension bushings are now composed of a higher-damping synthetic rubber that is 30% stiffer for smoother ride characteristics when compared with conventional rubber.
“The front suspension was completely redesigned,” O’Brien said. “We went to a four-point bushing setup for better rigidity and better noise isolation. Probably more importantly we’ve gone from a conventional rubber bump stop that basically has that very harsh feeling when you hit the limit of the suspension travel, to instead a hydraulic rebound spring stopper that manages that last bit of suspension travel much more comfortably.”
To help lower wind noise, aerodynamics have been improved to 0.33 Cd, a 0.02 lower coefficient of drag than the former Tucson.
Based on Hyundai’s internal tests at its R&D center in Ann Arbor, MI, the new Tucson has achieved better road noise (65.5 dBA), idle noise (61.7 dBA), and wind noise (67.2 dBA) measures than Toyota RAV-4, Honda CR-V, and Ford Escape (see image above)—“the result of our extra effort in terms of NVH and road noise isolation,” said O’Brien.Continue reading »