Lightweight trunk grooves for luxury cars

Provides safety for on-board power batteries even in the event of a crash

· Lighter than sheet metal

· High strength and stiffness

· Precision molding of large size composite inserts

Shanghai, October 14, 2021 – Tepexdynalite continuous fiber-reinforced thermoplastic composites are increasingly being used to replace metals in lightweight design
.
A new application for these composite materials from LANXESS is the manufacture of trunk grooves in the Mercedes-Benz S-Class that house the 48V on-board power battery
.
These composite parts can withstand high mechanical stress and are approximately 30% lighter than comparable sheet metal parts
.
"In the event of a crash, it must be ensured that the battery does not penetrate or damage the groove walls in any way
.
Our fabric-based composite material has high strength and high stiffness and enables this,
" says Dr.
Klaus Vonberg, application specialist Tepex at LANXESS
.
"This composite design also ensures that the trunk grooves are sealed to prevent fluids such as water, battery electrolyte, etc.
from infiltrating or seeping out
.
"

Functional integration to reduce costs

The safety components are manufactured using an economical composite moulding process, in which the blanks used are produced with a water cutting machine and measure approximately 110x80 cm
.
This blank is made of Tepexdynalite 102-RG600(2) based on polyamide 6 and reinforced with two layers of continuous fiberglass fabric
.
Lanxess' easy-flowing polyamide 6 Durethan BKV60H2.
0EF DUS060 is used as a re-injection material, enabling the integration of fasteners and stiffeners at low cost
.
60% of its mass is short fiberglass, which also makes it very strong and works perfectly with Tepex
.

complex molding process

The forming (draping) of the blank is carried out by means of a die press, which is a highly complex process due to the high draw ratio
etc.
This is because the composite material does not undergo plastic extension like the metal sheet, but needs to deform in accordance with the movement (overhang) of the fiber material, which means that the composite sheet must continuously supplement the deformation from the outside to the inside during the forming process
.
If the movement is too large, the fibers can inhibit the forming process, which can lead to breakage and affect subsequent processes
.

Integrated Simulation Saves Development Costs

LANXESS uses a series of computational models to accurately simulate the overhang process, so as to predict and analyze the forming effect and take corresponding measures
.
LANXESS not only determines the optimal 2D cutting geometry of the blank, but also performs a virtual analysis of the blank's forming behavior according to the customer's machining concept, enabling the early identification and elimination of defects
.
When designing these processes, huge savings potential can be brought about
.
“For the trunk grooves, we also judge when the critical shear angle of the fabric is reached during the forming process, where the wrinkling occurs and when the fibers start to break,” Vonberg said
.
"Our calculations and simulations also help ensure that the fillets of the part can withstand the expected loads
.
" The local orientation and pronounced three-dimensional contours of the continuous fibers themselves in the part areas, such as the fillets, are also simulated
.
This is a prerequisite for accurate prediction of mechanical component performance using integrated simulation
.
“All of this is part of the service we offer under the HiAnt brand, through which we support our customers’ development experts in designing trunk recesses,” Vonberg said
.

More series of applications

In the Mercedes-Benz C-Class, Tepexdynalite is now also used to create the trunk recess that houses the on-board power battery
.
“We also see great potential in electric vehicles – including safety equipment, complete battery system housings or components for the load space provided under the hood, because our lightweight construction materials are much lighter than metal and have Helping to increase the range of electric vehicles,
" Vonberg said as he looked to the future
.