3D CAD World

Andreas Minatti, Head of Business Development, Dr. Rudolf Randler, Head of Simulation and Dr. Norbert Haberland, Head of Business Development and Cooperation AT at Datwyler, take a closer look at how safe, sustainable and more intelligent mobility is being enabled by the evolution of components in the cars of the future.

As the automotive industry continues to evolve, so too does the intelligence of vehicles on the world’s roads. From those operating the internal combustion engine (ICE) to hybrid and fully electric alternatives, elements such as advanced driver assistance systems – such as self-parking or the ability to follow other vehicles in traffic, for example – require new and ever more complex components. The flexibility to develop new solutions for emerging automotive systems is critical, and therefore the way in which vehicle manufacturers are working with component suppliers is also evolving.

At any level, these systems require a high degree of sensor functionality, whether it be in the form of cameras, radars, lidars or lasers, and how these components are secured, housed and sealed is a critical element to ensure their optimal performance. This is extremely important as, given the roles of these technologies, their reliability is directly connected to the safety of the vehicles they are embedded within, and ultimately the safety of the global road-using public. To put this into perspective in terms of numbers, sensor technology supporting advanced driver assistance systems with the final goal of full autonomous driving is projected to be worth some $60bn by 2030, with one in 10 vehicles on the road relying on the technology in that same year.

Here, we will highlight three examples of evolving approaches to mobility components, covering the integration of advanced functionalities, the advantages of simulation where material properties are concerned, and the integration of vibration damping in control electronics circuit boards. We will also take a closer look at the simulation process and how smart sealing solutions can play a positive role where sustainability is concerned.

Advanced autonomous vehicle technology requires component innovation and integration of functionalities
Given the need for the extensive use of measuring (sensing) and regulation (control) electronics and technology in the so-called cars of the future, sealing components for such applications must not only fulfil the classic sealing function, but also a wide range of additional requirements and needs. Human machine interaction and machine-to-machine interaction require fundamental changes to be implemented in the products we deliver in the future, and many elements need to be taken into consideration.

In the field of autonomous driving, these include:

• The integration of functionalities
• Miniaturization
• Material combinations for multi-component parts
• New materials that combine different physical properties
• Multi-component manufacturing processes

To highlight how these additional requirements can be integrated, consider housings for control electronics as an example. Such housings are often manufactured using a thermoplastic material, that forms a stable shell to protect the sensitive interior from environmental influences. In order to fulfil this function permanently, the material must have a sufficiently high impact resistance and dimensional stability, in particular a high heat resistance and excellent resistance to any occurring media – such as spray water, salt water, greases, mineral oils, fuels and cleaning agents.

Depending on the area of application, other requirements can also play a role, such as good thermal conductivity, high electrical conductivity for shielding electromagnetic fields, or low specific gravity for lightweight construction applications. Since such housings are often a part of larger components, they must have integrated connection points for installation in the surrounding assemblies. Overmoulded metal bushings are a good solution for mounting housings on larger components in the engine compartment, for example, as they form stable connection points for fastening the housing to larger components in the engine compartment, prevent local plastic deformation of the housing and ensure that the assembly forces that occur are transferred and distributed evenly into the housing.

Another key component of the housing is the elastomeric seal, the functions of which go far beyond classic sealing. The elastomer forms a complex three-dimensional flexible and elastic structure, often based on Liquid Silicon Rubber (LSR), which covers the entire interior of the control electronics’ housing. In addition to ensuring the static seal between the housing base and cover and protecting the interior, the seal or the sealing material’s elastic structure keeps electronic components in place via buffer elements. This dampens damaging mechanical vibrations and significantly improves heat dissipation from active electronic components to the environment.

 

Using early stage simulation of material properties for new applications to minimize development costs
The most important applications for elastomer materials, especially in terms of their use for sealing purposes, are based on their hyperelastic mechanical properties. In the case of housings for electronics or sensors, the elasticity of elastomers ensures the maintenance of a sealing pressure over long periods of time and across a wide temperature range, providing the flexibility necessary where compensation of design tolerances is concerned, thus saving production costs. In many modern applications, for example in autonomous driving, the integration of functions via the combination of different physical material properties is of crucial importance. In addition to their elasticity, these elastomer materials must provide further physical properties:

• Hyperelasticity
• Flexibility
• Viscoelasticity
• Mechanical damping properties
• Optical transparency in defined frequency bands (or wavelength ranges)
• Electrical conductivity
• Heat conductivity
• Dielectric or magnetic properties.

Such combinations of properties can be achieved with the help of new polymer materials specially synthesized to meet specific requirements. However, the development of such materials is very time consuming and expensive, requires specialist knowledge and synthesis equipment, and the resulting performance may still be very limited.

The desired additional material properties can often be achieved in a more efficient and successful way by incorporating special fillers into the base elastomers – a well-known method to elastomer manufacturers. Depending on the type of filler, its particle size distribution, particle shapes and particle concentrations, the desired material properties can be tailored to customer needs, at the same time streamlining an often labor-intensive process.

Simulation can support the development of such materials with novel properties and offers an excellent opportunity to calculate and predict the effects of fillers in the polymer matrix. This accelerates the development of such multi-phase or hierarchical materials. Based on an existing material or on an idea for a new material, a model for the material structure is created. Based on this so-called representative volume element (RVE) and the intrinsic properties of the components (matrix and filler), the desired properties, such as the thermal conductivity or the elastic behavior, can be calculated using finite element analysis. Thus, the composition of the new material can be optimized at an early stage and subsequent laboratory work can be significantly reduced.

Ensuring vibration damping in control electronics circuit boards
Additionally, for specific applications, the viscoelastic material properties of elastomers play an important role, especially the damping properties. Certain damping properties of the material may be desirable to prevent components from vibrating too much during driving and under resonance conditions. An example of such an application is the integration of damping elements into the printed circuit boards of electronic circuits. In the example below, the circuit board is geometrically structured to provide the necessary flexibility within the overall design of the specific application. An integrated LSR structure supports the necessary flexibility and at the same time has a damping function to prevent damage caused by extended oscillations in case of resonance. The sensing and/or control electronics is mounted within a housing, and to fulfil its function reliably, it is necessary to mechanically decouple it from the housing and hence the vehicle vibrations.

Considering simulation early in the product development process to create optimal solutions
The development of new components and parts for next generation mobility applications has the potential to be a costly and often time-consuming process. Here, to eliminate the need for multiple prototypes, associated testing and analysis, working with a specialist components supplier with in-house expertise in the field of simulation can drastically accelerate speed to market, at the same time reducing capital expenditure in the development phase and beyond.

If we look at the simulation process itself and how it facilitates the development of new parts and their components, the ultimate aim is to design, visualize and optimize a virtual concept and then to support its transfer into real products and processes. By combining CAD tools to provide the geometries with simulation tools to create virtual models of specific parts, it is possible to calculate their functionality accurately before they even exist.

Following the CAD and as a part of the modelling stage, we have to assign specific material properties to the different parts of a component. Therefore, it is essential to perform a series of tests and then to model the necessary materials. This is an important prerequisite that can usually only be offered via specialist component manufacturers.

For many applications and products, experienced suppliers use their own tailor-made materials, so that customers do not have access to detailed material information from external sources. Therefore, suppliers need internal teams that are well equipped and have the skills to undertake all of the testing and mathematical modelling of these materials for simulations. In turn, these teams can also provide testing and modeling services for their customers, which adds an extra layer to the support offered throughout the process.

Turning to the functionality and design of parts, structural-mechanical calculations based on the finite element method enable the fine-tuning of the characteristics of a sealing element and the  optimization of its performance and design, thus allowing rapid progress from an initial draft to a convincing design proposal. There are many things and impact factors to consider – starting with the given mounting space, the influence of the applied loads such as displacements, pressures or temperatures, and the properties of the materials to be used. Top priority is to ensure functionality and seal integrity over a temperature range of often -40 °C (-40 °F) to +150 °C (302 °F), taking into account all design tolerances.

It is also necessary to look closely at how materials will behave in the production process, and here it is highly recommended that flow simulation is carried out. Everything from mold filling to optimizing the tools used for thermoplastic and elastomer molding processes can be analyzed, effectively simulating the entire manufacturing process, including the thermal management of the tools used and details such as temperature distribution over the mold to ensure consistency of quality.

The advantages for the customer of carrying out a product development within a co-engineering partnership with the supplier are clear, particularly where sealing applications are concerned. Sealing is very often the last element considered within a design, and the issues that can arise as a result of this element being carried out so late are many and varied, often requiring a solution that is not optimal for the design. All these dimensioning issues can be easily solved in the development phase with the corresponding design freedom, but are much more difficult to address in later phases after the design of some components or important parts of the system has already been frozen. By involving the supplier and using their specific knowledge at an early point in the development process, it is possible to optimize the design from the outset to ensure a global optimum as opposed to a local one.

Embedding sustainability in the mobility solutions of the future
One of the main focuses of electric vehicles (EVs) is to have a positive environmental impact, and here the processes involved in component development can help to bolster these goals. Sustainability starts with materials and can then continue to evolve as the process of component development progresses. Through optimizing the processes outlined above and the designs they are intended to produce, development teams can, in some instances, actually reduce the amount of materials required to deliver optimal performance.

From a design perspective, engineers specializing in sealing components are constantly looking at ways to incorporate bio-based materials and should have the capabilities in-house to develop materials from scratch that are tailor made to meet customers’ specific requirements. Ideally, they will also have in-house compliance experts, who in collaboration with material experts work to remove critical substances and identify those that may become obsolete under requirements such as Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH). If they see that a material may be critical in the future, they do not use it for the development of materials. The right supplier should be your partner to stay ahead of the curve – designing to fulfil future legislative requirements as well as those currently in place.

Smart sealing solutions can also have a positive impact where environmental sustainability is concerned. Sensor active layers within elastomers can detect force, touch or even leakage, and in some instances can detect the presence of media on the surface of the seal, leading to higher levels of capability in terms of predictive maintenance. This is a highly desirable capability within battery packs, for example, where any form of leakage can lead to reduced functionality or even overheating.

Electronic components such as chips and sensors can also detect elements such as temperature and pressure when integrated into sealing solutions. If we take the battery pack as an example once more, monitoring thermal conditions is a critical element as optimal functionality is only achieved within a specific temperature window. The ability to monitor the status of components, not just for the driver of the vehicle, but also for the entire system, allows service or maintenance to be scheduled when it is actually required, rather than at intervals determined by best guesswork.

Ultimately, the cars of the future will be markedly different to those ICE vehicles we are so familiar with today. Perhaps on the surface the consumer will still see a means of travelling from A to B, but beneath the surface a world of changes is taking place as the technologies evolve ever further toward fully autonomous vehicles. The way manufacturers and their suppliers work together must change as a result, and with an approach that is focused on co-engineering, together these futuristic visions will be realized far more quickly and far more efficiently than was ever thought possible.

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