{"id":3743,"date":"2026-05-29T11:00:26","date_gmt":"2026-05-29T09:00:26","guid":{"rendered":"https:\/\/www.aurelcz.eu\/impaktory-pro-hlavu-ochrana-nejcennejsi-casti-tela\/"},"modified":"2026-06-08T22:41:19","modified_gmt":"2026-06-08T20:41:19","slug":"head-impactors-protecting-the-most-valuable-part-of-the-human-body","status":"publish","type":"post","link":"https:\/\/www.aurelcz.eu\/en\/head-impactors-protecting-the-most-valuable-part-of-the-human-body\/","title":{"rendered":"Head Impactors: Protecting the Most Valuable Part of the Human Body"},"content":{"rendered":"

When simulating a collision between a pedestrian and a vehicle, head impactors are among the most important testing tools. They enable engineers to assess the risk of injury to the most vulnerable part of the human body. Head injuries are among the most serious consequences of road traffic accidents, as an impact can result in life-threatening conditions or long-term health effects. For this reason, pedestrian head protection receives particular attention during vehicle development.<\/span><\/p>\n

In the previous parts of this series, we explained <\/span>what impactors are<\/b><\/a> and why they are among the key tools used in pedestrian safety testing. The second article focused on the impactors used to evaluate bumper impacts on <\/span>pedestrians\u2019 lower limbs<\/b><\/a>. In this instalment, we will take a closer look at two types of impactors used for <\/span>head protection<\/b> testing: the child head impactor and the adult head impactor.<\/span><\/p>\n

The Basic Principle of the Experiments<\/span><\/h2>\n

During <\/span>pedestrian protection testing<\/b><\/a>, so-called test zones are defined on the vehicle. For head impact testing, this is based on the <\/span>WAD parameter \u2013 Wrap Around Distance,<\/b> which is measured using a flexible tape from the ground over the vehicle\u2019s bumper and bonnet. This parameter helps determine the most likely head impact locations in the event of a collision with a pedestrian. According to <\/span>ECE Regulation No. 127<\/b> or the <\/span>Euro NCAP<\/b> methodology, it is used to define the test areas on the bonnet. The exact boundaries of these zones are determined in a more complex manner, but generally speaking, the area between the WAD1000 and WAD1500 lines is used for child head impact testing, while the WAD1700 to WAD2500 area corresponds to the impact zone for the head of an adult pedestrian or cyclist.<\/span><\/p>\n

Head Injury Criterion (HIC)<\/span><\/h2>\n

The primary parameter used in these tests is the <\/span>HIC \u2013 Head Injury Criterion<\/b>. This metric expresses <\/span>the probability of a serious head injury<\/b> based on the acceleration profile recorded by the accelerometers inside the impactor during the impact event, typically over a 15 ms time interval (HIC15). It therefore evaluates not only the peak acceleration value, but also the duration over which the acceleration acts. The test is so important and widely used that some customers commonly refer to pedestrian head impact testing simply as <\/span>\u201cHIC testing\u201d.<\/b><\/p>\n

In pedestrian protection tests, HIC values typically range from several hundred to several thousand. A value of around 650 or lower is generally considered a very good result, whereas values above 1,700 indicate a high risk of severe head injury. HIC is therefore <\/span>a key criterion in vehicle development<\/b>, providing an objective assessment of how effectively the bonnet structure and the components beneath it can reduce the loads acting on a pedestrian\u2019s head during an impact.<\/span><\/p>\n

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Child Head Impactor (Child\/Small Adult Head form Impactor)<\/span><\/h2>\n

The <\/span>AC35<\/b> impactor simulates the head of a child or a small adult and has a mass of <\/span>3.5 kg<\/b>. It is equipped with an internal tri-axial accelerometer that records the acceleration profile during impact. These tests primarily focus on <\/span>the central area of the bonnet<\/b>. During the test, the impactor is launched at a specified speed and angle towards a predefined point on the vehicle body. The recorded data is then used to calculate the HIC value.<\/span><\/p>\n

At <\/span>AUREL\u2019s pedestrian protection testing facility<\/b><\/a>, these tests are carried out using one to three high-precision dynamic test systems and a precisely calibrated launching device. Following the impact, engineers analyse not only the acceleration profile but also the deformation of the bonnet and the behaviour of the underlying structure.<\/span><\/p>\n

Adult Head Impactor\u00a0<\/span><\/h2>\n

The <\/span>AD45<\/b> impactor simulates the impact of an adult pedestrian\u2019s or cyclist\u2019s head and has a mass of <\/span>4.5 kg<\/b>. It is primarily used for testing <\/span>the windscreen area and the rear section of the bonnet<\/b>, i.e. the areas closer to the windscreen and the A-pillars. These parts of the vehicle structure are more complex because they often contain rigid components beneath the surface, such as bonnet hinges, reinforcement members or structural body elements. It is precisely in these areas that achieving low HIC values is most challenging, requiring engineers to strike a balance between structural strength and the ability to absorb impact energy.<\/span><\/p>\n

in Head Protection: Insights from AUREL Experts<\/span><\/h2>\n

Modern vehicles incorporate several technologies designed to reduce the risk of pedestrian head injuries:<\/span><\/p>\n