Ford Motor Company partnered with WMG, Warwick University, Gestamp and GRM Consulting to develop a lightweight composite rear suspension knuckle for Innovate UK's C-Class.
Through the unique deployment of carbon fiber, and the use of optimized technology and customized production processes, the composite rear suspension knuckle can be reduced by up to 50% compared to currently manufactured steel components.
Through the integrated application of advanced processing technology and GRM Consulting's simulation technology, the team developed a design that is the first in its class.
The design of the component is perfect. At present, the production and testing of the components are underway, with the aim of developing a large-scale mass production process.
Composite knuckle-tether prototype
Steel knuckle - tie rod
introduction
In order to meet increasingly stringent emission regulations and customer requirements for extending the range of electric vehicles, the global automotive industry is stepping up efforts to achieve weight reduction goals.
Ford Motor Company launched the development cycle by redesigning a mass-produced steel suspension component to make it a lightweight component for a manufacturable composite.
The selected parts exhibit the contradictory requirements of 'minimum stiffness and maximum stiffness', 'buckling index and strength index'.
The weight reduction of this special non-spring support component increases the relative effectiveness of the spring and damper, improving occupant comfort and driver operability.
This newly developed composite part has proven to be suitable for high performance C-Class vehicles.
The delicate and perfect balance between material and process choices results in a total production cycle time as low as 5 min.
Cooperation is essential
This success story is the result of a two-year project funded by Innovate UK and implemented by a group of organizations including Ford Motor Company, Gestamp, WMG, Warwick University and GRM Consulting.
The project's name is 'Compound Lightweight Automotive Suspension System (referred to as 'CLASS')'.
Composite technology has inextricably entered the mainstream automotive engineering practice from academic research and the aviation industry to offset the increase in the inherent weight of electric and autonomous vehicles.
For the mainstream automotive industry as a whole, the complexity of composite performance remains a challenging problem to be overcome.
Although a large amount of research has been devoted to understanding composite materials from both industrial and academic levels, the art of predicting the performance of composite materials is still in its infancy.
GRM Consulting has decades of experience in developing predictive tools for the carbon fiber structure of racing cars. The company has made significant contributions to this project by avoiding traditional methods and reducing the number of mechanical tests required.
Using VR&D Genesis finite element analysis and design optimization software, GRM Consulting has adopted an optimization-based approach to reduce costs and reduce engineering time without compromising performance.
For a combination of infinite fiber orientations that meet strength, stiffness and buckling load requirements, it is necessary to understand the failure point of the mechanism. To this end, WMG, Warwick University uses their extensive understanding of material behavior and state-of-the-art manufacturing units to make automotive chassis Gestamp, the global leader in manufacturing, played an important role in designing components to meet the necessary functional requirements.
Design method
During the two-year development of the project, the design of such composite parts, from single material parts to multiple material designs, presented challenges for manufacturing and optimization teams.
Preliminary information from the book shows that the concept of lightweight knuckle for composite materials can be realized by a single material, sheet molding compound (SMC).
However, the long-term engineering schedule ultimately led the design engineering team to move to a variety of material systems: the prepreg layer imparts the planar mechanical properties required where it is located, and the SMC overmolding allows for complex geometric details and surfaces. External stiffness.
This uniaxial and biaxial prepreg combined with SMC means that the composite part can achieve mechanical strength, stiffness and buckling goals.
Other design challenges indicate that more innovation must be introduced while maintaining this design overview without affecting manufacturing.
After extensive simulation and testing work, the design was completed. This allowed the design to be optimized and refined to meet OEM durability and NVH goals.
The final weight reduction effect of the project is that, with the same function, the minimum weight loss is 30%, and the maximum weight loss is 50%.
Innovative manufacturing technology
A molding process capable of mass producing such high-strength, complex-shaped suspension knuckles has been developed. In the second quarter of 2017, production and mechanical testing of a demonstration component has been carried out.
The material is provided by Mitsubishi Rayon.
Prior to the start of the manufacture of this composite knuckle tie rod, the candidate carbon fiber material for CLASS was molded at Ford's R&D Innovation Center in Dearborn, USA, to optimize process parameters for maximum mechanical properties and shape. Precision provides help.
Summary of experience
Through the joint efforts of GRM Consulting and all participating companies, the project achieved structural and weight reduction goals.
The experience gained in this process helped engineers understand how to achieve optimal balance with multiple material designs.
As the project progressed, the VR&D Genesis optimization method was improved and the material selection method was improved to provide support for design and manufacturing engineers to meet stringent requirements.
Ford's project team accepted the challenge of 'delivering highly complex heavy-duty components', indicating that it would be relatively simple to deliver many other automotive components, if at all. There are indications that this has brought significant weight loss opportunities to the entire vehicle. .