Altair Engineering: How did simulation help Felix Rosenqvist move away from his crash at the Detroit Grand Prix?
The recent Detroit Grand Prix was filled with the usual adrenaline-fueled excitement you expect from an IndyCar Series race, with intense overtaking and high-speed chases. However, one driver recalled how dangerous the sport can be. As Felix Rosenqvist prepared to turn into turn six, his car lost traction and crashed into the tire-lined concrete barrier, luckily avoiding any serious injury. Watch the video below to see. A word of warning, this is not an easy watch.
The fall of Felix Rosenqvist at the Detroit Grand Prix
Racing car design includes a range of computer aided engineering (CAE) tasks including meshing of parts and complete vehicles, finite element analysis (FEA) of components, crash test simulations, optimization and computational fluid dynamics (CFD) for wind resistance analysis. As a result, every part of the vehicle is designed and optimized, then verified through crash tests and aerodynamic performance simulations. This verification process aims to meet the rigorous testing requirements of the Fédération Internationale de l’Automobile (FIA) even before a physical prototype is considered.
While speed and skill may ultimately win the race, ensuring driver safety is imperative, creating an additional layer of complexity for engineers to take into account. The holy grail of racing car design is one that is strong and lightweight. This ensures that the performance of the car is competitive while simultaneously ensuring the safety of the driver.
Finding the balance between speed and safety is a difficult challenge for engineers.
The use of innovative materials is a significant variable in the weight and strength equation. Options include high strength steel, stainless steel, aluminum alloy and composite structures. Composites, although extremely strong and light, introduce a high level of complexity for CAE analysis, especially for crash simulation. Different shapes and types of composites (woven, unidirectional) need to be modeled and fabricated differently. Behaviors are difficult to predict because the physical phenomena are very complex. A significant amount of data is required to perform the analysis, and specialized expertise and software are required.
Dallara Automobili is an Italian chassis manufacturer who designs with safety in mind. Several prominent drivers have officially attributed their survival after life-threatening crashes to the company’s design innovation. While speed is always paramount in the race, the company is committed to pushing the limits of what can be done from a technical point of view to protect the driver. They use Altair HyperWorks ™, a full-featured open-architecture CAE software containing pre and post-processing tools, multiple physical solvers, and optimization capability.
HyperWorks includes a bespoke environment to effectively aid crash and safety engineers in model building, starting with CAD geometry and ending with a solver set executable in Altair Radioss ™. From manikin positioning and seat mechanisms to seat belt routing, it provides an end-to-end analysis workflow that streamlines the setup of impact simulations in accordance with different regulations.
Altair Radioss simulation results compared to physical tests (courtesy Dallara Automobili)
Dallara won a contract to supply IndyCar teams with the “survival cell,” a basic rolling chassis called the IndyCar Safety Cell. As part of its research and development process, Dallara focuses on structural analysis. Studying the behavior of materials under stress allows engineers to simulate the performance of any number of different metals, plastics, and composite structures in vehicle components.
By harnessing the power of HyperWorks, Finite Element Analysis (FEA) and optimization methods are used effectively to conduct trade-off studies, find optimal structural configurations, choose materials and, most importantly, improve the safety of the machine. vehicle.
Dallara IndyCar optimized with Altair HyperWorks
Ready for the test
The entire racing package must comply with IndyCar rules and regulations. Computer simulation in conjunction with indoor and track testing helps Dallara meet series certification tests.
With safety paramount, Dallara runs computer crash simulations with Radioss, Altair’s nonlinear and linear solver that simulates dynamic loading in crash and impact studies. For the survivor cell, for example, Dallara must demonstrate that after applying a load of four tons to the nose box, nothing breaks.
In this process, engineers run several evaluations using Radioss. When they are satisfied with the results, they move on to physical tests at the company’s factory. Next, engineers visit a test center in Milan, Italy, to perform head-on crash tests. They smash the survivor cell with a dummy pilot to try and replicate what might happen on the racetrack. The survival cell must not break down. In the frontal test, the nose box must dissipate the crash energy.
Dallara repeats the simulation and physical testing process for other parts of the vehicle. For example, engineers perform rear impact structure thrust tests, in which there should be no failure of the structure or any attachment between the structure and the survival cell; rear crash tests, in which there must be no damage to the structure behind the rear wheel axle; side impact structure thrust tests, in which there must be no structural failure or attachment between the structure and the survival cell; and the side crash tests, in which there must be no damage to the monocoque and no failure of the seat belt attachment and the extinguisher.
Another important test is carried out on the roll bar, a steel structure that protects drivers in the event of a rollover when the car is struck from the rear or the side. Engineers apply 12 tons of force to the top of the hoop. There must be no structural failure in a plane 100mm below the hoop.
Dallara also performs a test in which he applies seven tons of force to the front area of the chassis, in front of the driver – anticipating a scenario where one car could land on top of another. This test is not required by the IndyCar, but because Dallara strives to build the safest cars, he believes it is an important test to perform.
After all testing is complete, engineers apply an additional safety feature to both sides of the monocoque – a Zylon composite panel made up of multiple plies. This optimized ballistic material has saved the lives of racing drivers on numerous occasions.
The complexities of composites
The IndyCar monohull weighs 178 pounds. It is a carbon composite structure with an aluminum honeycomb core. The side panels are made from steel and there are two CNC machined aluminum bulkheads for the pedals and dashboard. The fuel tank is also made of carbon composites.
Composite materials offer high performance, so designers are always looking for new shapes for parts and defining how different materials can be put together. The goal is to reduce weight since composite materials weigh less than aluminum or steel but often absorb a similar amount of energy.
The physical phenomena associated with composites are complex and a great deal of data is required to perform an analysis. With metals, material properties are isotropic, so the main design variable is shape. With composites, directional stiffness can be altered by orienting stacked plies of different fiber directions to create a layered structure that can be tailored to meet the requirements of each part of the structure. As such, Dallara works with leading suppliers to the raw materials market to learn about new developments in Carbon Fiber Reinforced Polymer (CFRP) materials as well as with software developers like Altair to help determine virtually the best configurations. of laminate and ply orientations for the structure.
Dallara has implemented a multi-step process to analyze carbon chassis structures, like the IndyCar. Phase 1 involves the preparation of the model. In phase 2, engineers define the materials, boundary conditions and variables to be used in the analysis and optimization (see Driving design through simulation). The visualization and analysis of the results is carried out in phases 3 and 4. All of these steps are implemented in HyperWorks.
When evaluating models, Dallara examines the material response for each ply of the laminate. Material data from many experimental tests are used; Dallara has worked with Altair over the past few years to develop material models and new software features to meet specific requirements.
The dynamic analysis of CFRP material is multifaceted, involving the selection of failure criteria to define damage mechanisms such as delamination and cracking, failure propagation, inertial phenomena, instability, energy absorption and strain rate effects. Radioss provides engineers with an ideal environment to vary material parameters and failure theories in order to find material models that match the available test data. Once these models are defined and verified, simulations can be performed reliably for conditions that cannot be easily tested.
With all of this in mind, simulation software enables engineers and designers to produce high-performance, safe vehicles that withstand the grueling forces of a race or worse, an accident. Accidents do happen, especially in high risk sports like the Detroit Grand Prix. With extensive dynamic load analysis and design optimization capabilities, Altair’s solutions ensure operator safety while staying at the forefront of performance.
Altair Engineering Inc. published this content on June 25, 2021 and is solely responsible for the information it contains. Distributed by Public, unedited and unmodified, on 25 Jun 2021 03:06:07 PM UTC.