Take a look at the below picture, who is missing?
Everything looks alright in this picture, right? We see a nuclear family of crash test dummies. Since the 70s crash test dummies have been used for testing car safety with the most commonly used dummy being based on the average male size and weight. The female in this picture is actually a scaled-down male representing the smallest 5% of females (1.5m tall and 46kg in weight) in the 1970s, so actually, she is the 12-year-old daughter in the family!
EU Laws
In the EU, there are five tests a car must pass before being allowed on the market: one safety-belt test, two frontal-collision tests, and two lateral-collision tests. In no test is an anthropometrically correct female crash-test dummy required. There is one EU regulatory test that requires what is called a fifth-percentile female dummy, which as we have touched on before, does not accurately represent the female population. Even with this regulation, there are a number of data gaps. For a start, this dummy is only tested in the passenger seat, so we have no data at all for how a female driver would be affected - something of an issue you would think, given women's 'out-of-position' driving (see 'Attention Female Drivers' linked in related posts). Astrid Linder (see below) argues that technically there already is a legal requirement for accurate testing of female crash dummies. Article 8 of the legally binding Treaty of the Functioning of the European Union reads, 'In all its activities, the Union shall aim to eliminate inequalities, and to promote equality, between men and women.' Clearly, women being 47% more likely to be seriously injured in a car crash is one massive inequality to be overlooking!
Astrid Linder
Astrid Linder is a Swedish engineer and researcher in motor vehicle safety. Linder holds multiple professorial positions, including Professor of Traffic Safety at the Swedish National Road and Transport Research Institute (VTI), Adjunct Professor of Injury Prevention at Chalmers University, and Adjunct Associate Professor at the Monash University Accident Research Centre in Melbourne, Australia. She earned her PhD in traffic safety from Chalmers and holds an MSc in Engineering Physics from the same institution. Her research primarily focuses on traffic safety, crash testing models, injury prevention, and crash-related countermeasures. Her work has been widely published and presented internationally.
What does she do?
Linder with VTI has been extensively working on creating an accurate 50th-percentile female crash-test dummy (50F, aka Eva). EuroNCAP (a European organisation that provides car safety ratings for consumers) have said that since 2015, they have used male and female dummies in both front-crash tests. With further investigation, Linder is quite the caveat: "To my knowledge, little or even no such data has been applied to crash dummies. In any case, EuroNCAP acknowledged that 'sometimes' they do just use the scaled-down male dummies. We have different muscle-mass distributions. We have lower bone density. There are sex differences in vertebrae spacing. As Stoffregen (see 'Attention Female Drivers' linked in related posts) has noted, even our body sway is different. These differences are crucial when it comes to injury rates in car crashes.
Meet Eva
In her TEDx talk (linked below), Linder talks about how her team started by creating a mathematical model of a female, just as one has been done for males. The average male is 1.77 metres tall and weighs 78kg, and the average female, Ava, is 1.66 metres tall and weighs 65kg. Aside from these differences, the models differ in geometry, weight distribution and joining stiffnesses, which correspond to differences in muscle strength. This section of the talk really triggered my inspiration as a product design engineer as it's product design engineering to the core, it's really opened my mind to the opportunities that I have in my future career.
Let's Talk Engineering
Prototype Pelvis
Using standard materials from current crash-test dummies where possible, the sitting bones were cut off and sot pads added in as replacement as well as hip pads. It was found that polyurethane foam could be a suitable body material due to its ability to replicate a soft core covered with firm skin.
A Quick Terminology Lesson on the Lumbar, Thoracic and Cervical Spine
The thoracic spine is positioned at the centre of your upper and middle back, running from the base of your neck (cervical spine) to the bottom of your rib cage, located just above your lumbar spine (lower back).
The Spine
We want a spine that is movable in all directions. Below is a linear vertebra, the base component of a lumbar spine. A flat steel spring covers the motion resistance between the vertebrae and rubber bumpers in between to eliminate metal-to-metal clashes which can alter the test readings.
The mounts of the vertebrae are perpendicularly rotated so when mounted together they can stack and as a body move in all directions. To add rotation, the same concept was interpreted but the vertebra was split in two with bearings placed in between. Putting it all together, in a stack, they were able to achieve straight vertebrae in the lumbar spine and angular and rotating vertebrae in the thoracic spine. The cervical spine (the neck) was inspired by the bioroid system (existing male dummy) but made more compact. The muscle strength is resembled by anterior and posterior springs which are pulled by wires. An oil-filled damper, rotated by a wire, is placed to smooth out the motion and signify the weakness in our necks.
Chest and Shoulder Design
The upper arm design is designed to be softer for a softer interaction with the seat. Inside the chest, there is a small sternum (breastbone) which is mounted on the moveable shoulder system. This part of the design does not interact with the spine and therefore, does not present any disturbances to the spine motion.
The pins sticking out of the spine, connect the soft body to the spinal motion. The pin on the upper shoulder mechanism also acts as a clavicula (collarbone), which enables a simplified shoulder motion forward, letting the body sink into the seat.
Workshop Time - Putting it all together
Inside the dummy, there are four sets of sensors which are combined gyros and 3-axis accelerometers. This allows for readings of motion and rotation at four locations in all directions and the difference between the sensors.
Testing
The initial test was the same as the volunteer testing made over 50 years ago. This was at a speed of 7km/h, where the body does not experience any injuries but the tendencies of the body can be recorded. Comparing the results, through video analysis, they could say that their models have necks which are a little too weak alongside a body which is a little too stiff. So they are aiming for now improving this feature of their models in the next progressive stage of design. Prototyping is all about learning, and this is what this brilliant team have highlighted. It is inspiring to see methods which I have myself used on much smaller scale projects used in projects such as these. It makes the mistakes as learning curves valid, that all engineers must go through this process to produce something truly great. If you wish to read more about their developments, I have linked their report at the bottom of the blog.
Comparison Photos
I am a visual learner so I understand more through a visual assessment of material. If you are like me, here is a photo and video highlighting the differences between the two dummies and videos testing Eva which highlight the details mentioned above. For example, notice in the video how Eva's shoulders sink into the char during the impact test. All photos and videos have been taken from Goto 10 video conference with Astrid Lidner and her team, I have linked it at the bottom of this blog.
Comparison on male and female dummy in chair
Testing Eva
Overview
Linder and her team have said that their vision is that by 2030, injury protection performances on new cars will be assessed for both men and women. My meticulous research into this dummy alone has really made me realise the impact my degree can have on millions of people in the world. It has been inspiring to be able to apply the mechanical engineering knowledge I have acquired at the University of Glasgow to fully appreciate and understand how this dummy has come to be, alongside learning new aspects of medical terminology and its integration into engineering. Everything can be a learning curve, the materials and systems used are recorded for me to acknowledge with any future projects I am involved in. This research has not only validated the importance of a meticulous design process which fails and excels throughout but also, how as a designer, I want to contribute to making this world a more equal place.
Additional Sources of Information on the Topic
Astrid Linder Tedx Talk: https://www.ted.com/talks/astrid_linder_eva_the_female_crash_test_dummy
Smithsonian Article:
BBC News Article:
Goto 10 Conference:
The SET Report:
Book, Invisible Women by Caroline Criado Perez:
Chapter 9
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