VIPER has the combined testing resources and technical expertise to help your organization achieve the most from your vehicle’s suspension system. Whether the goal is to optimize your race vehicle’s grip to gain precious fractions of a second on track, or help accelerate the development of the ride tuning of a prototype passenger vehicle, VIPER can tailor a test program to suit your development needs. We offer services that cover the entire spectrum of suspension development testing from on-vehicle data acquisition to 8 Post vehicle dynamics shaker testing, along with the expertise to explain to you what it all means.

Vehicle Dynamics Shaker Testing

VIPER operates the first 8 Post vehicle dynamics shake rig in North America. Our rig has been sized to accommodate a wide range of vehicles including most anything from a golf cart to an up-armored HumVee.

What is an 8 Post? Simply stated, the rig has four hydraulic “wheel loaders” on which the vehicle is positioned simulating the ground inputs into the suspension, along with four pneumatic “aero loaders” which attach to the vehicle’s body and simulate both the inertial and aerodynamic forces that a vehicle experiences. The wheel loaders comprise the first four actuators and can be used by themselves in a more simple 4 Post test, or in conjunction with the aero loaders arranged in various configurations for either a 7 Post or 8 Post test.

What is the difference between a 7 Post test and an 8 Post test? While 7 Post rigs are far more common, the extra aero loader, or body attachment, allows the VIPER rig to accomplish two things; replicate the chassis warp degree of freedom, and more accurately replicate load transfer dynamics.

Do I want to test warp? 7 Post testing was developed primarily within the open wheel formula ranks. These cars typically have monocoque structures with very high torsional stiffnesses. Accordingly, these stiff vehicles do not experience much torsional, or warp, displacement. Therefore, the three points-defines-a-plane assumption is quite valid. However, when testing a tube frame vehicle as in a NASCAR vehicle, or production based race vehicle as in a Porsche 997, the bodies do flex and with the additional aero loader we can replicate this dynamic.

Secondly, and more importantly, having 4 aero loaders allows us to better replicate the load transfer dynamics that occur in a vehicle. Again, 7 post testing grew out of the open wheeled world where aerodynamic forces relative to inertial forces account for a greater contribution of the vehicle’s total loading. Aerodynamic forces are a more distributive loading, whereas inertial forces act across a vehicle’s suspension. With 3 aero loaders, there is only one way to provide a roll moment. However with 4 actuators, closely coupled with each corner of the vehicle, the VIPER rig has the capability to better replicate the load transfer dynamics (e.g. roll couple distribution) as they occur in the vehicle. In vehicles that have a higher contribution from inertial forces relative to the aerodynamic forces, the extra control translates to better testing fidelity.

Rig Specifications

As noted above, the VIPER rig is substantially larger than most customer rigs in North America.  The following describes the vehicles we can accommodate: Vehicles up to 14000 lbs in weight Wheelbases between 60 and 128 inches Track widths between 45 and 80 inches

Customer Experience

VIPER has given as much attention to the customer experience as we have to rig development and test methodology. In so doing, we strive to provide a high level of value to our customers.

• Rig data acquisition that can accept up to 36 channels of on vehicle instrumentation.
• Computer controlled shock and bump stop heaters.
• Complimentary usage of the shock development lab during shaker tests.
• Three customer data terminals which allow independent review of data coming from shaker testing.
• In house data analysis tools which allow flexible viewing of data in nearly any conceivable format: time history, x vs. y, PSD, histogram, etc.
• Aeromaps can be incorporated in data post processing.
• Building wide public wireless internet.
• Suspension Technologies 8 Post consultancy available.

Services

• 4 post characterization test (under development)
• 7 / 8 Post characterization tests (sine sweeps, etc.)
• 7 / 8 Post track performance replication (AKA “track file”)

Suspension Subsystem and Component Testing

Housed in the same building as the 8 Post shake rig, VIPER has a fully stocked shock development lab. This lab boasts a Roehrig 4K electromechanical shock dynamometer, two shock build stations, nitrogen supply, and a substantial supply of shock rebuild tools. Additionally, VIPER has the capability to help develop semi-active or active shock absorbers. We have a full compliment of lab grade power supplies, oscilloscopes, as well as a dSpace prototype controller.

Services

• Shock Audit.
• Rebuild and balance.
• Suspension Technologies consulting.
• Shock development program management.

Through our Virginia Tech partnership, VIPER has access to a state-of-the-art quarter car development rig located in the Performance Engineering Research Laboratory (PERL) at the Institute for Advanced Learning and Research in Danville. This quarter car rig has two posts; one hydraulic wheel loader, and one electromechanical aero loader. As in the 8 post, the wheel loader simulates road inputs into the quarter car system, while the aero loader simulates inertial or aerodynamic loading.

Data Acquisition Services

As with any engineering development program, data is of paramount necessity. Without data it is impossible to accurately assess the baseline state of your system or any developed improvements. VIPER has a large compliment of data acquisition equipment including data loggers and instrumentation. We currently have a PI sigma system, a VBOX GPS system and are in the process of developing our own custom data acquisition system. In terms of sensors, VIPER has an ever increasing stock of accelerometers, linear potentiometers, rotary potentiometers, gyros, IR temperatures sensors, shock load cells, laser ride heights, etc. as well as a full set of Kistler Roadyn wheel force transducers with NASCAR adaptations (Daytona Prototype adaptations coming soon).

Services

• Vehicle instrumentation.
• Data collection.
• Data analysis and consulting.

Areas Under Development

Both VIPER’s service and research components are always pushing the boundaries of the state-of-the-art. Here a few areas in which were actively focusing our attention:

• 8 Post shake rig testing based vehicle simulation model development.
• 8 Post rig and driving simulator real time simulation connection for simultaneous hardware-in-the-loop and driver-in-the-loop testing.
• Motorcycle shake rig testing.