In testing commercial vehicle seats and interior, developers must consider boundary conditions that diﬀer from those of the passenger car. Nevertheless, experience from the car can also be used for trucks and mobile work machines. IAV uses its tried and proven infrastructure and its expertise gathered over decades for testing commercial vehicles.
The diﬀerences between passenger cars and commercial vehicles even begin at mileage level. For trucks it is usually well over 1,000,000 kilometers which means that interior components, like air vents and cover ﬂaps, are exposed to far more wear and tear. “As a result of the higher mileage, the seats are also subject to signiﬁcantly more stress and strain”, reports Jörn Klenner, head of the Interior / Seat Testing & Class-A Surfaces department at IAV. “And we also need to allow for diﬀerences in the environmental impact assessments in relation to cold and hot temperatures, sun, humidity and moisture – one simple reason being because the driver’s cab also serves as a living room and bedroom.”
Added to this are the diﬀerent economic boundary conditions. Commercial vehicle development is a business-to-business matter whereas most of the time the passenger car segment involves the business-to-consumer environment. This is why there is an even stronger focus on the practicality and reliability of all components for trucks and mobile work machines – because a failure lasting several days can cost the year’s margin of a truck which means that immobilization must be avoided at all cost.
Often identical basic principles
However, developers do not need to reinvent everything. Much experience and many of the testing facilities from the passenger car world can also be applied to the commercial vehicle world. “The basic principles are in many cases identical – when testing components, of course, we need to increase the stress and strain on them”, Klenner says. “As a result, we can also use our automobile expertise for the test specifications.” IAV is currently working on a project for an OEM where the company is developing a test specification for simulating the process of getting in and out of a vehicle. The experts are also building on the experience from the passenger car segment for the environment simulation tests for a tier-1 supplier.
IAV can provide commercial vehicle customers with extensive facilities for component testing. These include many test rigs developed in-house, such as the ball impact tester that can be used for simulating the horizontal and vertical impact load on all interior components. On top of this, there are thirteen climate chambers, of which four are large enough to accommodate an entire driver’s cab. Climate-resistant robotics are capable, for example, of actuating the vents of an air outlet in the same way as in realworld use by the customer and, derive the force-travel or force-angle diagram in the three-dimensional space at different temperatures.
Comparison with CAD data
Temperature diﬀerences also play a key part in the three-dimensional measurement of components. A 3-D surface scan or photogrammetry lets IAV’s experts determine whether a component conforms to the CAD data and how it deforms under mechanical and/or thermal load. “This very quickly shows us which component, for example, is responsible for undesired joint proﬁles or bulging”, Klenner says. Klenner and his colleagues also focus attention on the electrostatic properties of components. If they attract too much, they could permanently soil up as a result of static charging and, in some cases, be virtually impossible to keep clean.
“We can test the entire vehicle interior as well as the seats”, Klenner says summarizing. “This includes the instrument panel, the door and side trim, the roof liner, insulation and damping, the ﬂoor coverings, the sun visors, the center console as well as the module cross member for the instrument panel.” But particularly important in this case is the knowledge in the heads of his team. Unlike the passenger car segment, commercial vehicle OEMs only develop a completely new model every few years which means they may have less experience in testing seats and interior. Intelligent transfer from numerous automobile projects lets IAV ﬁll this gap.