Hutchinson, a supplier of industrial transportation systems, has developed front and rear axles made of fiberglass-reinforced composites for the new Peugeot 208 FE, which is said to consume only 1.9 liters of gasoline per 100 km from a conventional metal The axle / suspension system was turned to a composite-based system that reduced the weight by 20.4 kg, or by about 40%. Peugeot worked with Total, Paris, France, Hutchinson to design the car To explore a viable approach to meet the stringent European regulatory requirements for emissions of less than 90 g / km of CO2 per kilometer by 2020. It is clear that 208 FE easily reached this standard, according to reports, each of which Km of CO2 emissions is 49g, which for a pure (non-plug-in) hybrid electric vehicles, is a prominent world record.
Hutchinson Composite Front Axle Suspension Blade Schematic
Hutchinson used his experience to design 208 FE axles as a materials formulating company and a manufacturer of vibration control technology for the automotive, rail transportation and aerospace industries Hutchinson refers to the structural composite core of these shafts as a ' Blade 'because of its design features: Four key features integrated in one component - Suspension, Steering, Vibration / Noise, and Anti-roll. During the development process, design engineers integrated / eliminated 12 Components, including: spring, spring seat, anti-roll bar, anti-roll bar accessories, anti-roll bar connecting rod and fork arm (steering part) components.
Peugeot 208 FE, a hybrid concept car equipped with front and rear axles made of approximately 50% unidirectional epoxy / glass fiber (photo from Peugeot)
The composite has a blade design that reduces the weight of 20.4 kg (about 40%) compared to a metal suspension, where design engineers can integrate or eliminate 12 parts (photo from Peugeot)
The new suspension actually originated from a component Hutchinson produced for another European carmaker 20 years ago, recalls Bertrand Florentz, technical director at the Hutchinson Composite Technology Center ("CTeC") Ready to go into production, but due to the preference for traditional steel suspension, the production plan was eventually canceled.As 2020 tougher emission standards are imminent, non-compliance of the company will face penalties, so that today's car manufacturers Is facing tremendous changes in the market situation.At the same time, Hutchinson early accumulation of suspension application experience, but also make it quickly respond to the Peugeot 208 FE new, unique design development requirements.
When designing a car suspension, the first consideration is that this part assembly needs to withstand both static load (fixed weight of the car) and dynamic load (generated during operation), corresponding to the tensile force distributed over all three space shafts , Compressive and shear forces, ie, longitudinal, vertical and transverse loads. When driving, it can withstand dynamic load up to 5 times the static load on the car, therefore, in the key structural dimensions and overall design of the part Dynamic load is an important consideration.
In response to these multi-axial loads, Hutchinson's initial 'grand' design was to simulate the main suspension structure with an orthotropic model with uniform beam distribution, which, as a bottom line, allowed engineers For local rigid features necessary to meet the basic static load requirements of the car.
If the material's mechanical properties and thermal properties are unique and independent in three mutually perpendicular directions, it is an orthotropic material. In contrast, the properties of the isotropic material are in all directions In addition, a material can have homogenous (uniform) or non-homogeneous (non-uniform) microstructures.A material, such as rolled steel, is a natural orthorhombic anisotropy and homogeneity (Uniformity.) The design of a homogenous orthotropic composite material, the key is to use the same 'microstructure' (ie, material, here an epoxy resin) and most of the unidirectional fiberglass , A laminate structure that varies in thickness and orientation to create a laminate structure that will allow design engineers to model the part using finite element analysis (FEA) by adding or subtracting specific Region of reinforcement material to handle a variety of three independent axis deformation and load problems.
Therefore, the second step in the design process was to conduct a detailed finite element simulation of the suspension at the Hutchinson Research Center, where the simulations were used to mimic the stiffness of the composite blades and to provide a detailed laminate structure including The orientation of the fabric and the local thickness.As a result a blade design with 3 laminated structures is obtained: a laminated structure 1 where the ball joint is here with the column (thicker, and more particularly, With a high degree of longitudinal rigidity to ensure that the wheel guide) phase; laminated structure is installed on the rubber steel shaft bracket connected to the middle of the two sides; laminated structure three, stent (thin and especially special It is ensured that the vertical stiffness of the suspension) between the middle part.
The types of loads considered in FE simulation are vertical load (symmetrical and asymmetrical), longitudinal load, lateral load, corner load, lateral impact load, and fatigue load.The simulation outputs the blade stiffness, displacement and Kinematics, as well as local stresses and strains in the resin and fiber, and then compare the stress and strain with laboratory-derived material allowances, including the necessary 'material failure' factor.
In a parallel development process, researchers conducted a comprehensive characterization of materials using both laminated samples and virgin resins, with specific process parameters such as resin transfer molding (RTM), total reaction heat, Thermal expansion and thermal contraction (in all three axial directions) and fiber concentration, etc. are calculated from the measurements obtained by differential scanning calorimetry (DSC), contact angle measurement and dynamic mechanical analysis (DMA) These data were used to generate a viscoelastic model of a suspension blade and then imported into ABAQUS finite element analysis software (Dassault Systèmes, Waltham, Mass.) Thermodynamic analysis was used to determine the heating And to calculate and predict machining-induced deformation and residual stresses during the cure cycle in order to optimize the machining conditions after the part design is completed while ensuring that the parts are continuously formed on the normally-produced molds and equipment.
Although Hutchinson designed the composite front and rear axles for the Peugeot 208 FE, the front axle is more complicated due to the increased steering elements.The final suspension design consists of a bow-shaped main structure of glass-fiber-reinforced blades with a thickness range Between 12 and 15 mm, the volume content of the fibers exceeds 50%. The length of the blade is about 1.2 m with a nominal width of 140 mm and a bow depth of about 315 mm. In eliminating all the above components, the composite shaft / suspension design It incorporates all the features of a traditional metal suspension such as: The bow-shaped suspension blade is mounted to the vehicle in its pre-pressed shape during assembly and acts as a single spring across the width of the front of the vehicle for the absorption path Vibration. The composite blades are each articulated (one vertical, one longitudinal) to the body of a car (BIW) on each side of the composite blade. When the blade is bent or compressed in response to road vibrations, To be elongated in the transverse axis between the fixings.In order to accommodate this lateral extension, the rubber base provides the necessary lateral displacement resilience while they additionally filter the road vibration and noise.These hinges are Encapsulated into a pair of steel blades on each side of the bottom case.
Each tip is connected to a steel ball, which in turn is connected to connecting rods (rods) that are loaded onto the vehicle through vibration absorbers and at these points the blades are subjected to maximum load and therefore , An extra enhancement to this area was made in the blade design by replacing the anti-roll bar with the function of anti-rolling itself, due to its inherent flexural rigidity and fixed symmetry. In fact, based on the symmetry of the deformation, the right wheel also moves up when the left wheel moves up, which is actually a definition of the anti-roll connection.The steering is conventional and separate from the blades, with a wheel-connected bogie passing through the left, Right connecting rod and rotate directly.
Florentz says that designing and building a composite shaft / suspension requires at least five times the engineering effort to design the same metal parts, but in a sense it takes extra time because steel As a traditional material with a large amount of test data and qualified data, but for composite parts, the final characterization of the material must be obtained after the layer-by-layer aging, simulation and post-processing obtained.If the use of composite in similar applications Materials, it is safe to assume that most of the additional engineering development time can be eliminated due to passing material certification, testing and simulation from one project to another.
At the JEC 2015 in Paris, France, the suspension was the highlight of Hutchinson's booth
At JEC 2015, visitors were able to see clearly on the exhibited suspension system how the suspension design separates the spring-blade structure from the steering function of the front suspension
Although this technology is still considered conceptual, this application deserves our attention and potential. For a long time, composites have long been regarded as not suitable for the structural applications of commercial vehicles. Therefore, the composite industry has done a lot of hardships To prove the potential of composite materials to replace metals and believe that vehicle manufacturers and consumers can make their own judgments thanks to Hutchinson's significant step in this direction.