Featherweight wheel could be in the offing.

Vehicle wheel rims from fiber-reinforced plastics have reached a stage where they could give traditional steel or aluminum a run for their money. According to researcher Andreas Büter at the Fraunhofer Institute for Structural Durability and System Reliability (LBF; Darmstadt, Germany), such wheels, as manufactured on a test basis since 2001 by BTE Hybrid-Tech (Grube, Germany) from sheet molding compound with glass-fiber reinforcement (the second generation uses carbon fiber), can offer high specific strength at lower weight than metal alternatives.

So far the wheels have chalked up more than 250,000 km (155,000 miles) during tests but they still have not received the nod of approval from Germany’s technical inspectorate, TüV, which so far is unwilling to accept the same test methods used for metal wheels for evaluation of plastics composites versions. Büter believes that may change in two to three years.

Together with other Fraunhofer Institutes, LBF is developing a simulation method that, he says reliably predicts the quality of rims and how they take punishment such as curb impact, potholes, and road salt. “First we will produce a computer tomography image of the wheel. It enables ascertaining length, alignment, curvature, and density of the fibers [which are] crucial for the strength and load capacity of the material,” Büter says.

Based on these results the LBF simulates the microstructure of the material in a virtual unitary cell which, for the first time, permits depiction of arbitrary material configuration.

Applying the unitary cell results, the LBF can use a numerical component model to simulate how the wheel handles road curves or crash behavior. The program, LBF Wheel Strength, calculates stress and elongation occurring in the material under various loads. Büter says the simulation method is transferable to most reinforcing materials such as glass, carbon, or aramid fibers. Simulations are followed by physical tests.

…and packaging

Laminate packs greener cup of coffee

Taking stand-up pouches yet one step further, retailers are considering ’flexible cans’ to ’green’ some of their packaging solutions. That is what international food discounter Aldi Süd (Ketsch, Germany) is doing to pack coffee pads in a seamless, round film tube. The PET/tie/aluminum/ tie/polypropylene (PP) laminate “Cyclero” film concept was developed by web processor Huhtamaki Deutschland (Ronsberg, Germany), with equipment partners Aisapack (tube-making machinery; Vouvry, Switzerland), Landenberg Verpackungsmaschinen (Wipperfürth, Germany), and Herrmann Ultraschalltechnik (welding equipment; Karlsbad, Germany).

The coffee pads for Aldi are packed at rates of 60/min in the flexible cans. The tube is formed from the film laminate and top bases are die cut for sealing by ultrasonic welding to the tube. A form-fill-seal machine stacks the pads in the modified atmosphere tubes, injects nitrogen to prevent oxidation, and welds the other end to form the flexible can packaging.

Aldi opted for ultrasonic welding because compared to heat welding there is neither heating up nor cooling down time required, making cycle times faster. Martin Fischer, marketing manager at Herrmann, says Aldi has been able to assemble double the weight of coffee pads, compared to previously used brick packs or paperboard, on a single pallet.