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19 Oct 2005  -  Switzerland / Italy

Composite door hardware module on Lancia Ypsilon® car offers integral hip protection with no foam pad, no molded inlay

GMT Composites provide cost, part, & weight reduction, functional integration, improved crash performance, sound damping, & ease of assembly.

A new integrated door hardware module –  produced by the Ranger Group for Italian automaker, Lancia’s Ypsilon subcompact passenger car – meets all European side-impact and hip-protection requirements with no foam pad, injectionmolded inlay, or other carrier reinforcement. Additionally, Lancia was able to use a minimized steel bar in the door’s outer skin. The module provides intrusion protection through clever design and high-tech, glass-mat thermoplastic composites from Quadrant Plastic Composites. 

Integrated door hardware modules – benefits & challenges 
Many types of integrated door-hardware modules (carriers) have been commercialized in the past 15 years, including allsteel, gas-assist injection-molded hermoplastic, long-fiberreinforced thermoplastic (LFT), and hybrid units combining several material types. While these modules reduced a significant number of components and fasteners, lowered weight, and facilitated on-line assembly into the vehicle, they offered no additional occupant protection in a side-impact crash. All automakers must meet intrusion-protection standards for the passenger or driver. But in Europe, there is also an additional hip-protection requirement to meet. Since there was no easy way to integrate this function into existing door module designs, a separate component – either a foam pad or injection-molded inlay – had to be installed. Ironically, this step added both weight and components – two of the features that door hardware modules were designed to reduce. 

A Different way to build a hardware module
Tier 2, Ranger Group set out to find a better way to design and build an integrated door hardware module that would incorporate integral hip protection and other key features such as:
•• Multiple fixation holes & locators,
•• Screw domes,
•• Speaker & door-handle pockets,
•• Door-opening system guidance & fixations,
•• Wiring fixation and guidance, and
•• Window-opening system & guidance.
Ranger Group narrowed its materials search to 2 categories of composite materials – long-fiber reinforced thermoplastics (LFT) and glass-mat thermoplastics (GMT) – and designed aggressive test requirements for the materials to pass.

Multiple material candidates
Several GMT and LFT materials were compared:
•• Classic GMT with 40% glass (chopped mat) – baseline material,
•• Direct LFT (D-LFT) with 40% glass,
•• Injectionmolded LFT pellets with 40% glass (G-LFT),
•• Sandwich of strategically placed GMTex™ high-impact, textilereinforced composite (middle layer) and Classic GMT 40%-glass composite. 

Meeting demanding test requirements
To meet its performance requirements, Ranger Group worked in partnership with Quadrant Plastic Composites to determine the best material for this new application. First, all candidate materials were subjected to a series of standard small-scale laboratory tests to measure compression, tensile, and impact properties. Top-performing candidates were then subjected to a series of rigorous crash tests on full-size molded door modules loaded on a 912-kg sled at room temperature. Both a side-impact test (with a 200-mm UTAC pole and speeds increasing from 0.92-1.47 m/s penetration rates until part failure/breakage) and a secondary hip-impact test (with 220x220-mm flat impactor and speeds increasing from 1.62- 1.78 m/s until part breakage) were conducted to assess crash worthiness of different materials in the module’s design. Improvements to the clamping design allowed steel-like deformations to be approximated with plastic composites. Use of a limited rotatingsteel bracket allowed for initial deformations with low stress to the part. All tests were videotaped. Results are presented in the table to the right. Careful comparison of energy absorption at break revealed that at 400 J and 0.92 m/s penetration, the G-LFT grade absorbed just 120 J of energy before breaking in half, whereas the D-LFT grade absorbed 250 J at break, also splitting in two. The baseline classic GMT grade with 40% glass absorbed 800 J and did not break due to the consistent distribution of its much longer glass fibers. The best-performing grade was the combination layering GMTex™ high-impact, textilereinforced composite in the middle, surrounded by top and bottom layers of classic GMT with 40% chopped glass. The part molded from this materal absorbed 1,000 J of energy at the test’s most difficult speed of 1.48 m/s and 1,000 J of energy without breakage. 

The same materials were also subjected to the hip-impact test (with flat impactor and speeds ranging from 1.62 -1.78 m/s, also at RT). Results were as follows: The G-LFT part at 900 J of impact energy absorbed 450 J; the D-LFT part at the same test conditions absorbed 500 J ; the classic GMT part at 1200 J absorbed 900 J; and the Classic GMT / GMTex™ part at a more severe +/-45° impact angle and 1440 J of impacting energy absorbed 1300 J. The hip pad on both LFT parts shattered into sharp pieces, whereas it remained intact for both the GMT and GMT / GMTex™ parts. The classic GMT grade with 40% chopped glass was selected by Ranger Group for the final part. It provided the best combination of performance and cost for the part design without being overengineered. 

Multiple benefits in a single design
Use of a classic GMT with 40% chopped glass led to cost and weight reduction, increased design freedom, functional integration, sound absorption, crash resistance, ease of assembly, corrosion resistance, and recyclability for this part. In addition, it passed the demanding European hip-impact test without the need for a foam cushion or injection-molded inlay.

Source : Quadrant Plastic Composites AG