Our Base design for Drive shafts and springs
The N-Flex® drive shaft design is based on the patented NEMOS technology. Unidirectional glass fibers are arranged in two layers of composite coils, transmitting the torque of the drive train. The outer set of coils is purely tension-loaded while the inner coils are compression-loaded, resulting in radial and axial equilibrium of forces.
The composite coils of each layer are decoupled by gaps, the outer and inner layer are decoupled by high-performance elastomer material. This allows the coils to remain bending compliant which enables the entire shaft to be flexible in multiple directions. Additionally, the decoupling induces a virtually unidirectional force transmission through the composite coils which means high strains can be applied resulting in an excellent torsional elasticity.
The N-Technology basics
Common laminate
Starting point
For a bi‑axial state of stress, composites in general offer the potential to orient the load carrying fibres in each of the main stress directions. For a torsion load and the resulting shear within the tube wall, this means a ±45° orientation in the wall, leading to tension and compression stresses in fibre direction and perpendicular to fibre direction.
The Problem
Even though an arrangement as described already puts fibres in the load path, those fibres are usually not utilized in full. The low strength perpendicular to fibre direction often results in laminate failure at comparatively low load levels. In many arrangements, the fibres are only used to ¼ of of their capacity.
classical laminate
N-Technology LaminatE
The Solution
In the N‑Technology hybrid material, an elastomer is used to decouple the differently oriented layers as well as the load carrying fibre strands within the layer. Due to its high flexibility, the elastomer is stretched or compressed without tearing. This leaves the fibres to carry most of the loads in length direction, maximizing the use of their load bearing potential.
Benefits
The mechanisms described are key to all the benefits given for our individual products. The uniquely enhanced material usage can be translated into less weight, lower inertia, smaller components, higher performance and lower cost or a combination of those. Additionally, the hybrid material can be designed to electrically insulate or transmit, to absorb load peaks or to damp the transmission of noise.
Our approach
Simulation
When N‑Technology was invented to cope with the challenges posed by efficiently harvesting wave energy, advanced simulation models were key to developing an “ahead‑of‑the‑pack” technology. In the past two years, we have consistently enhanced our simulation skills and models to a point where we are able to calculate the complex hybrid material behaviour within a highly parametrized and automated simulation environment.
Design
Highly loaded, yet low-cost composite parts need a design to reflect that aspiration down to the last pin. Our team of mechanical engineers is working consistently to optimize press-fit load introductions and integrated flanges as well as to provide assemblies and devices for manufacturing and testing.
Manufacturing
The production of our complex components takes place in-house on specially developed manufacturing equipment. For efficiency and process quality, production is largely automated. Customer-specific designs can be implemented quickly and cost-effectively.
Testing
When introducing new products, especially any made of a novel hybrid material, the trust of the customer has to be earned. We are working hard to build that trust by testing the components on our own test rigs and externally in static tests, cyclic tests, temperature tests, creep tests, bend revolve tests, acoustic tests, adhesion tests, field tests and more. The test results further serve certification processes as well as validation of our simulation tools.
