Comment: Driving diversity in crash testing with virtual modelling

The automotive industry has undergone a myriad of innovations, but few have been as positively transformative as vehicle crash testing. Advancements have revolutionised how the industry approaches vehicle safety to ensure products meet strict regulations and prevent fatalities in the event of a collision.

One of the most invaluable developments in crash testing has been the use of subjects to understand how the human body is impacted. Interestingly, the first crash test subjects were cadavers – thankfully, the industry has moved on from this ghoulish operation. Instead, Anthropomorphic Test Devices (ATDs) – otherwise known as “crash test dummies” – are used to study factors that influence occupant safety, like interactions with vehicle structure, airbags, windscreens, and seatbelts. The ATDs are equipped with sensors that measure forces, moments, displacements, and accelerations to predict and mitigate the extent of injuries that a body could sustain.

To say that ATDs are instrumental to the crash testing process would be an understatement. In 1970, when the use of ATDs started to become common place, the rate of road fatalities was 13.5 per 100,000 people; by 2021, that rate had dropped to 2.3 deaths per 100,000, showing the incredible impact these efforts have made. However, in an increasingly digital age, the industry has evolved over time to complement physical testing with virtual models that can further improve occupant safety.

One size doesn’t fit all

ATDs have been pivotal in the advancement of passenger safety, but they have their limitations. Factors like high costs, availability, the need for recalibration after tests, and the lack of consistencies in impact response mean that manufacturers have previously been limited in their ability to crash test a multitude of body types. More recently, the industry has shown trends and exciting new developments towards a more accurate representation of dummies through the Virtual Human Body Model. Toyota THUMS, GHBMC are some of the commonly used human body models today. Along with the 50th percentile male and 5^th percentile female models, 25^th and 95^th percentile models for both male and female, a pregnant female, an elderly 70YO, as well as 3, 6, and 10-year-old child models are available. By employing simulation in the form of virtual modelling to augment physical testing, engineers can measure and analyse vast amounts of data, from a range of potential situations and, crucially, from various test subjects. This important work on realistic virtual human models enables automakers to include and support and analyse a diverse spectrum of humans quickly and efficiently to enable better insights and design decisions. 

Virtual modelling: a revolutionary solution

Virtual modelling provides engineers with a holistic and highly accurate view of the object’s behaviour in real time. As the industry is beginning to introduce ATDs replicating different body types, virtual modelling can be brought in to help this transition and work alongside physical testing. By using high-performance computing (HPC) which possesses increased computing power, the virtual modelling process is significantly accelerated and able to simulate millions of elements in a short period of time, producing enormous amounts of data for analysis. Additionally, this process is very scalable meaning that crash simulations produce more data over time that can increase the accuracy of results.

By augmenting physical testing with virtual modelling, engineers gain a deeper understanding of how different bodies will react in different situations, enabling them to maximise passenger safety and optimise structural performance. Virtual modelling has led to the development and deployment of digital ATDs replicating bodies of all shapes and sizes – engineers can now simulate the average female body, a pregnant female body, an elderly body, and a child’s body, to name a few. These models possess highly detailed musculoskeletal systems and organs to accurately replicate injuries. With virtual modelling, engineers can gather vast amounts of data to predict how a body could be affected in a real-life incident.

For example, engineers can use digital ATDs to understand how female occupants deviate from the standard seating position. This is because they often have shorter legs, so the angles of their hips and knees differs from the typical seating position. For elderly individuals, who usually have decreased bone strength and increased brittleness, virtual modelling can help understand the impact that the sudden inflation of an airbag would have on them in the event of a collision. Finally, with regards to varying sizes between people, digital ATDs can help manufacturers understand the risk of a heavier occupant overwhelming the airbag and allow them to make the necessary adjustments. This important work on realistic virtual human models ultimately helps engineers to include and support a diverse spectrum of body types to generate better insights and design decisions.

The importance of diversity in crash testing

The world is a very diverse place, and with more people than ever driving regularly it is imperative that every effort is made to keep everyone safe, irrespective of gender, age, or size. As the world continues to change, and the automotive industry evolves, the use of simulation in crash testing remains will continue to play a pivotal role. With the extensive use of virtual modelling supplementing physical testing, engineers will be able to continue to improve safety and move us closer to the goal of 'Vision Zero’ – eliminating traffic fatalities once and for all. 

Chris Kuang, product marketing manager, Ansys