Documentation:FIB book/Motorcycle Helmet Comparison from an Injury Biomechanics Perspective

From UBC Wiki

Introduction

Helmets are the key safety feature for motorcycles. There are many helmet variations that aim to help prevent head and neck injuries. Unlike other vehicles, a motorcycle rider's only legally required form of accident safety equipment is their helmet, so there is less protection in the event of a crash. Helmet effectiveness affects all motorcycle riders since 71% of motorcyclists fatalities are due to head injuries.[1] Helmets have been shown to reduce the risk of death of motorcyclists in collisions by 42% and reduce the risk of head injury by 69%.[2][3] This makes helmets the most common and most protective piece of equipment for preventing injuries related to head impacts.[2] With these factors in mind, it is important to assess each helmet type and how effectively these protect a motorcycle rider's head in the event of a crash.

Several studies have been conducted to test different helmet types: open-face, chin bar and full-face. They utilize finite element modelling, drop testing, and impact testing on cadavers and anthropometric test dummies (ATDs).[1][4] In this literature research, we will analyze the effectiveness of the different types of helmets to determine their protective benefits and safety for motorcycle riding.

Background

The helmet is a piece of protective equipment that has been used throughout history and the design has gone through many phases. The use of helmets in sports began with leather bonnets used in the late 1800s and early 1900s.[5] Their design went unregulated until 1952 when the British Standards Institute published the world’s first crash helmet standard which led to the first cadaver drop testing for helmet development in 1960.[5] Despite the later regulation, the development of motorcycles in the early 1900s prompted the use of hard shell open-face helmets, which gained popularity as early as the 1930s.[2][5]

In the United States, motorcycles became widely available in the 1940s and 1950s shortly after the end of World War II.[6] The use and effectiveness of helmets in war inspired their use as a method of head protection for motorcyclists prior to being legally necessary.[7] This influenced the National Highway Safety Act (NHSA) that was introduced in 1966 and requires the use of helmets.[6] The act was adopted by every state except California by 1975.[6] On the other hand, helmets only became legally required in British Columbia, Canada in 1996 as a part of the Motor Vehicle Act which is currently enforceable with a fine starting at $138.[8][9]

Open-Face Helmets

Open-Face Helmet

The open-face helmet was the first and earliest version of the motorcycle helmet, but the materials used to make it have changed significantly over time.[2] Hardshell helmets were first made from cardboard and glue, then linen impregnated with varnish resins, and finally, modern helmets are fibreglass layers with expanded polystyrene (EPS) foam padding.[2][5] The hardshell is necessary to distribute applied forces, reducing the localization of the impact and diminishing the likelihood of a depressed skull fracture.[2] After the design of the pure hardshell helmet, helmets started being designed for function based on the understanding of human biophysical characteristics and kinematic head injuries.[5] The resulting design changes involved the addition of insulation to cushion the head which absorbs energy and lowers the inertial load.[5]

The open-face design does leave more of the head and face area uncovered in comparison to the chin bar and full-face designs.[1][2] However, this lack of coverage means there is better ventilation and increased mobility, causing open-face helmets to still be commonly used in more humid climates.[10]

Chin-Bar Helmet

Chin-Bar Helmets

Chin bars are an important addition to motorcycle helmets. They are commonly found in full-face helmets and pivoting helmets (where both the visor and the chin bar can pivot upwards), although there is not much research on the level of force absorption in pivoting helmets.[2] Chin bars can be connected to the overall helmet in a variety of different ways offering different levels of protection. A study conducted in 2001 by Richter et al. showed that around 16% of total helmet damages occur at the position of the chin bar, which shows the importance of this feature in preventing facial injuries.[11] Overall, the frontal area of a helmet is the most likely area to suffer impact in a motorcycle accounting for 50% of impacts, with 40% of those impacts taking place in the chin bar, making them essential parts of the helmet.[12]

The chin bar usually consists of two distinct layers: a liner made of a thick layer of open-cell comfort foam to absorb the impact and a shell made of a thinner layer of thermoplastic to hold its shape.[13] A softer and thicker foam will have a higher ability to absorb forces in the event of an impact, and a rigid outer shell will maintain the helmet’s shape during impact, avoiding indentation, therefore protecting delicate facial structures from penetrating injuries. An excessively soft outer shell will indent and cause facial injuries, which could propagate to the skull and brain. An excessively rigid liner will propagate forces to the skull and, in turn, cause excessive head acceleration, leading to brain and facial injuries. Overall, chin bars are a very important feature of a helmet. The chin bar helmet sections of this chapter will focus on the chin bars as a feature without the presence of a visor.

Full-Face Helmets

Full-Face Helmet

Modern full-face helmets have six main parts: a hard thin outer shell, a soft thicker inner liner for impact absorption, additional padding for comfort, a retention system, ventilation, and a visor. The rigid outer shell disperses energy by spreading the impact over the total surface area of the helmet thus reducing concentrated stresses during impact, and helps prevent penetration due to sharp objects that a motorcyclist might come in contact with.[2] The helmet's outer shell provides the total helmet with a rigid structure to prevent disintegration from the abrasive nature or pavement in the event of a crash.[2] Having a rigid structure is one of the most critical roles of the outer lining of the helmet, as it maintains the helmet’s integrity even after multiple impacts.[2] The outer shell does provide some impact energy absorption, but a relatively small amount, roughly 10-34%.[2] The inner liner helps in providing additional energy absorption and can absorb more energy than the outer layer.[2] This is done by plastically deforming or crushing the inner material making up the inner shell. [14] This material is often EPS foams, due to their ability to provide multidirectional resistance during impacts and lightweight, or a honeycomb-reinforced liner.[14] The visor on full-face helmets are often made from a strong and transparent material. These visors are not designed to help in impact force absorption or force distribution, as they generally will bend and break based on impact force and direction. [15] They mostly help to prevent dust, road fragments, rocks or sharp objects from entering a rider's eyes or causing facial wounds.[15]

Helmet Injury Prevention

Sustainable Forces

The majority of head impacts for motorcyclists are oblique, meaning that impact has a speed component that is tangential to the surface being impacted.[16] As well, it has been found that the average angle between the head impact velocity and impact surface is 44°.[16] In data collected from Neuroscience Research Australia, the primary head related injuries in helmeted motorcyclists made up 24% of all injuries analyzed, with superficial (14%), fracture (5%), and intracranial (14%).[17] In the same study, neck injuries made up 9% of the injuries motorcyclists sustained, with the most common being fracture (5%), superficial (2%), and soft tissue (2%) injuries.[17] The mean pre-crash speed for motorcyclists is 52.3 ± 23.9 km/h, and the majority of cases involved a crash with another vehicle.[17] The impact damage on helmets has a highest recorded location associated with any frontal damage (78.5%) and the next highest damage on the rear (61.5% of cases).[17]

AIS - Abbreviated Injury Score

An AIS code indicates the body region and injury severity. The score itself indicates how likely a person is to die from an injury but does not account for the effect on quality of life. The effect on quality of life is significant when concerning facial injuries as a person's face is their identification and how they make first impressions. Since the AIS does not take this into account, facial injuries only range from an AIS severity of 1-4 with 95% of all facial injuries are categorized as AIS 1. However, the AIS scores for traumatic brain injuries (TBIs), cervical spine injuries and fractures range from 1-6. In terms of motorcycle-related injuries, a study found that the primary cause of AIShead 2+ injuries were lateral forces (58.8%), and the secondary causes were impacts along the sagittal plane or forces between the frontal and occipital lobes (27.3%).[11]

HIC - Head Injury Criteria

The FMVSS defines a HIC15 limit of 700, where impacts resulting in a HIC15 score over 700 are likely to result in an injury. A study conducted by Bonin et al. compares helmet crush with HIC, speed and acceleration.[18] Forehead impacts ranged from 2-10.5 m/s and HIC equal to 700 corresponded to the 5m/s direct impact.[18] In terms of road speeds, this implies that a helmeted motorcycle rider is likely to sustain a head injury through the forehead if the impact occurs at more than approximately 18 km/hr. In another study, helmets impacted an anvil at 7 m/s, and the corresponding HIC values ranged from 1417 to 1439 with a maximum acceleration of 200 g.[19] These values provide further confirmation that impact speeds above 5m/s result in HIC greater than the FMVSS limit of 700.

Common Injuries with Each Helmet Type

In general, non-penetrating head injuries are caused by short-duration accelerations acting on the head and its contents. These acceleration injuries are the most common and dangerous form of injuries for motorcyclists and are often caused by blunt impact rather than by penetration.[2] In a study conducted by Park et al., a logistic regression model was used which determined that wearing any helmet helps prevent not only mortality, but also ICU admission, longer hospital stays, AIS 2+ cervical spine injuries and TBI.[20]

Open-Face Helmet

While the popularity of this helmet has declined in recent years, the lower restriction around the neck at the base of the helmet does provide a reduced likelihood of neck injury.[1] However, there is less coverage for the head and face making facial injuries nearly twice as common.[1][21] A study by Meng et. al. conducted a finite element analysis (FEA) on multiple helmet types and found that the open-face helmet leaves riders susceptible to brain strain and higher facial forces than the other helmet types due to larger linear and rotational, motion and acceleration experienced.[4] Common injuries that result from this higher brain strain include craniomaxillofacial injuries and TBIs.[22] In a 2014 study conducted by Cini et al., it was found that open-face helmet users more commonly experience zygomatic, mandibular, orbital, dentoalveolar, and jaw fractures when compared to full-face helmet users.[23] As a result, for those with facial injuries after a motorcycle crash, 41% of open-face helmet users require surgery, whereas only 19% of full-face helmet users needed surgical intervention for their injuries.[23]

Overall, the open-face helmet may reduce neck strain, but an unprotected face is much more susceptible to injuries that are typically more severe.[24] Even incidents unrelated to crashes can occur with this helmet, such as eye injuries from dust or insects.[2] While facial injuries are not as commonly fatal as neck injuries, damage to the face that results in scarring or deformities can greatly impact a person's quality of life and their identity.

Chin-Bar Helmet

Chin bar helmets are very important in preventing facial injuries, as well as injuries on the temples and sides of the skull, in the event of a crash resulting from a frontal impact to the head, as they provide an added layer of protection to the user’s face.[11] Due to high velocity impacts directly on facial structures, 15% of people who suffer facial injuries in motorcycle accidents also suffer moderate to severe brain injuries.[13] A 2016 study found that frontal impacts also cause forces to propagate that result in basilar skull fractures.[12] The level of propagation of these forces is highly dependent on the material used for the liner and the shell of the chin bar.

Currently, the standard for chin bar safety testing is the Snell Test, which drops a 5kg impactor towards the chin bar of a helmet which has been secured to a platform and points directly upwards, with no head form being used.[13] A study conducted in Dec 2000 proposed a drop test using a 5 kg magnesium alloy head form.[13] This study showed that the HIC scores derived using the drop test were more consistent with the expected scores given the materials used (smaller HIC scores for softer liners). This is due to the Snell test lacking a head form, causing it to focus on the rigidity of the chin bar (general chin bar deformation) rather than its ability to protect the user. The drop test measures the acceleration of the head form, which creates more accurate predictions of injury.

Full-Face Helmet

In general, full-face helmets perform better in protection against head and cervical injuries than other helmet types.[25] Full-face helmets have shown 64% better protection against head and cervical injuries than open-face helmets.[25] Full-face helmets have additional protection against facial injuries that can, though not often lethal, have significant effects on quality of life.[25]

In lower-face and mid-face impacts, full-face helmets have been shown to reduce brain strain in testing on a THOR ATD by 38% and 15.8%, respectively.[4] For facial forces, lower and mid-face impact forces were reduced by 61.5% and 96%, respectively.[4] However, force is not evenly distributed, with concentrations around the lower face.[4] Full-face helmets also help reduce the tensile force in the neck by 29.3% in lower-face impacts while increasing the neck tensile forces by 14.4% in mid-face impacts.[4]

Discussion

Effectiveness

While injuries and effectiveness can vary between the three helmet types identified above, helmet use helps prevent fatal injuries to motorcycle users regardless of the type. From the details highlighted in the previous sections, it can be seen that the differences between all of the helmets are quite vast. Full-face helmets offer better protection but can cause neck injuries due to their restrictiveness when compared to open-face helmets. They also have visibility limitations from the visor but have fuller coverage, whereas open-face can provide better peripheral vision but has less coverage.[1] Additionally, full-face helmets may not be suitable or comfortable to wear in all weather conditions, such as humid, cold, or hot weather because they lack ventilation. In contrast, open-face helmets do not have these limitations and are more comfortable to wear in various weather conditions.[26] Nonetheless, full-face helmets provide better surface area coverage for the user compared to the other helmet types.[2] One study conducted finite element simulation to analyze the protection performance of the three types of helmets covered in this chapter, with their results indicating that the full-face helmet resulted in a lower peak head form acceleration (197 g) than open-face helmets (235 g).[1]

On the other hand, open-face helmets provide better ventilation which improves comfort for users[10] and their design also has less neck restriction which reduces the likelihood of neck injuries.[1] However, their lack of coverage leaves a rider's face vulnerable to injury.[1][21][23][24] Furthermore, the open face of the helmet exposes riders to particles, insects, small rocks and other debris present on the road that can result in non-accident related injuries.[2]

As mentioned before, helmets with chin bars reduce the risk of facial and head injuries by providing extra layers of protection to the face.[11] The chances of helmet ejection is also lower in full-face helmets with chin bars.[27]

Injuries

Head and facial injuries are quite common in a motorcycle crashes. According to a study by Yu et al., the risk is more prevalent for non-helmet users as they are four times more likely to sustain head injuries and ten times more likely to obtain a brain injury.[16] Similarly, half-face helmet users were twice as likely to sustain a risk of head or brain injury when compared to full-face or open-face users.[16]

Another study conducted impact testing for different types of helmets against the possibility of acquiring a skull fracture, concussion, or subdural hematoma. From their results, it was evident that the full-face helmet provided better protection against those injuries as opposed to an open-face helmet.[28] Adding on, the occurrence of brain contusion is also more prevalent with the usage of open-face helmets than full-face.[29] Full-face helmets are better at decreasing the effects of direct forces, thus providing more protection against facial injuries than open-face helmets.[29]

On the other hand, cervical fractures were more prevalent with full-face helmets, due to the additional mobility restriction around the neck.[29] Full-face helmets also limited head rotation in response to angular forces which often resulted in occurrence of fatal neck injuries.[29] In the context of facial injuries, full-face helmets proved to be superior to open-face helmets.[1]

As discussed, full-face helmets provide better protection against facial and head injuries, but fall short in neck mobility and neck protection. On the other hand, the open-face helmet provides more neck mobility reducing the likelihood of neck injuries; however, there is increased likelihood of serious head and facial injuries which are more commonly fatal. Both of these helmet types are subject to other factors affecting their ability to prevent injury, such as improper wearing of helmets or environmental factors.

Controversies

There are a number of controversies when it comes to helmet regulation, testing and protection. There is an abundance of standards for helmets and a lack of any regulatory body to enforce proper assessments. This leaves the helmet approval process in the hands of the manufacturers with no form of accountability. Manufacturers do not need to provide proof of regulatory assessment to the consumer or otherwise unless there is legal request or lawsuit. With that said, the large number of standards results in many possible helmet testing methods. In British Columbia, Canada helmets need to be certified according to either the Department of Transportation (DOT), Snell Memorial Foundation (Snell) or Economic Commission of Europe (ECE) tests.[9]

The required tests provide some information on the general effectiveness of the helmet but have flaws. The DOT test consists of a series of tests with an appropriately fitting head form in different temperature conditions and after a period of immersion in water.[30] The tests performed include a drop test on a hemispherical anvil and a drop test on a flat anvil. These are both done with a head form and the helmets are dropped in 4 different angles. The next test is a penetration test and involves 3 penetration impacts with a test striker.[30] Lastly, a retention test is carried out by keeping the helmet and head form static, applying loads in tension, and measuring the displacement of the head form relative to the helmet.[30] This differs from the Snell test where the helmet-head form setup is rolled.[31] The DOT test also does not provide a chin bar specific test.

The Snell test consists of a combination of evaluation criteria to test for the helmet's effectiveness and safety including peripheral vision, stability when placed on the head, inspection for sharp edges and comfort, and performance in impacts. The performance test for the Snell test involves a series of guided fall impacts where the helmet is placed on a head form and dropped from different heights. The pass criteria depends on the size of the helmet and head form used.[31] For the chin bar tests, a helmet is placed on a rigid surface with no head form and impacted with a 5kg piston at 3.5m/s. The pass criteria is based on the maximum deflection.[31][13] This creates a problem where the chin bar is evaluated based on the hardness of the outer shell and not on the general safety and likelihood to cause an injury in a frontal impact.[13]

Finally, the ECE test certification is one of the most widely accepted standards and has some of the strictest testing.[32] This testing includes evaluating a helmet's impact absorption, rigidity and retention system.[33] These tests have a number of different head form sizes to be tested with drop tests in various testing conditions, at differing points on the helmet and impact geometry.[33] Often, if a helmet is ECE approved it is also will meet the DOT requirements.[32] However, this is not the same for DOT helmets, as the ECE testing is more rigorous. There is some controversy over the testing as newer regulations have removed penetration testing, which tests how easy it is for the outer shell to be penetrated by a sharp object.[33] Additionally, critics of the test point out that testing is always done in the same location of impact for all tests.[33] This allows for the manufacturer to reinforce the specific location being tested and thus be approved without actually meeting the ECE requirements.

Although it is legally required to wear a certified helmet, there is no regulatory body preventing manufacturers from selling novelty motorcycle helmets that do not meet any of the helmet standards (DOT, ECE, SHARP).[34] As these helmets have not been tested on well-defined requirements, there is a greater chance that they will not provide adequate protection during a crash. It is believed that novelty helmets are still chosen over standard tested helmets due to inadequate information, false expectations of all helmets providing equal protection and misjudgment of the risk of novelty helmets.[34] Regulatory bodies such as NHTSA have pushed to have information campaigns on the importance of buying standard test helmets through identifying helmets that failed the FMVSS No. 218 (motorcycle helmet standard) testing requirements.[34] However, due to the number of novelty helmets on the market, it was unsustainable to test all against the FMVSS No. 218, and often, the test done had incomplete results.[34] Due to this, novelty unregulated helmets are still regularly sold and worn by motorcycle riders.[34]

In addition to the regulations and approval processes themselves, consumers are also faced with conflicting options when selecting a helmet. They can choose to protect their face and head from serious injury with a higher coverage helmet such as the full-face design, or they can choose to allow more mobility to protect their neck from injury and better ventilation using an open-face design. Either way, the user needs to choose which area they would prefer to protect while risking the other. There is currently no tested helmet design that can serve as a compromise and protect all of the vital areas of the head and neck.

Future Research and Limitations

So far, testing for motorcycle helmets has included FEA, ATD tests and cadaver testing,[4][35][36] however, there are areas for improvement when using these methods.

Some studies have addressed that the fixation and fit of the helmets are likely important in reducing injuries to the head and face, as well as deaths.[37] Most helmets do not have variations in sizing and most riders do not wear their helmets with proper fixation in an attempt to maximize comfort or because of the sizing issues, so this reduces the helmet’s protective capability.[37] These issues mainly affect females and children[37] but none of the literature explored in this chapter has evaluated how fit or fixation of the helmet affects the AIS level and/or amount of injuries sustained, so this is one area that requires significant research.

One study showed that when simulated, the material properties of the helmet had an influence on deformation and strain energy experienced.[38] However, many studies are limited as they do not explore the effects of these material differences among helmet types. Therefore, future research should consider comparing helmet types with similar material compositions and seek to determine whether material types are influencing the results.

The main limitations of the FEA studies are the assumptions and approximations made to reduce the study’s run time and model complexity, while increasing the validity of the model.[35] Therefore, the influences of muscle activation, and in some cases, rotational head acceleration are unaccounted for,[35] thus decreasing the amount of information that can be gathered from any set of models. Another point to consider is the need for experimental data to validate FEA models and other simulations. There is little experimental data available for motorcycle helmets due to the lack of sensors included in helmets, the randomness of crashes and the ineffectiveness of ATDs to be biofidelic under typical motorcycle crash test scenarios.[35] So, it may be pertinent to consider reducing these limitations.

Including sensors in motorcycle helmets has been a consideration. We believe that the following are reasons why sensors have not been implemented: 1) increase in the production and market costs of helmets which could further reduce the use of motorcycle helmets, 2) sensors in helmets would be one time use as one impact may damage the sensors and 3) Implementing sensors in current helmet designs may require the redesign of helmets or may cause user discomfort.

ATD studies have limitations specifically pertaining to their accuracy in predicting real world human body responses. The ATDs commonly used in motorcycle helmets testing, usually THOR and Hybrid III,[4][35][39] are not designed to be biofidelic in the impacts sustained during helmet testing and thus cannot provide the most accurate results for helmet testing.[40] Therefore, designing an ATD or head form that can be biofidelic in drop testing and various impact testing is a necessary step to improving data in the field.

Cadaver testing is also used often for helmet testing,[35] however, it is a known fact that cadaver tissue does not retain accurate biofidelity during testing. In the case of testing brain injuries with helmets, cadavers are unable to provide injury response data as the brain tissue does not mirror a real world response, and can only be considered an approximate estimate of sustained injury.[41] Therefore, other information that indirectly relates to injury must be used to determine the severity of head injuries or the possibility of brain injury when wearing helmets.  

The gaps mentioned need to be addressed first, followed by additional biomechanics research to improve the understanding of motorcycle helmets, to reduce possibility of injury, encourage changes in the production market and for policies to be implemented to protect motorcycle users.

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 M. Tabary et al., “The effectiveness of different types of motorcycle helmets – a scoping review,” Accident Analysis & Prevention, vol. 154, p. 106065, 2021. doi:10.1016/j.aap.2021.106065
  2. ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 2.13 2.14 2.15 2.16 F. A. O. Fernandes and R. J. Alves de Sousa, “Motorcycle helmets—a state of the Art Review,” Accident Analysis & Prevention, vol. 56, pp. 1–21, 2013. doi:10.1016/j.aap.2013.03.011
  3. ↑ B. C. Liu et al., “Helmets for preventing injury in Motorcycle Riders,” Cochrane Database of Systematic Reviews, 2008. doi:10.1002/14651858.cd004333.pub3
  4. ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 S. Meng, P. Ivarsson, and N. Lubbe, "Evaluation of full-face, open-face, and airbag-equipped helmets for facial impact protection," 2023. doi:10.2139/ssrn.4384214
  5. ↑ 5.0 5.1 5.2 5.3 5.4 5.5 J. A. Newman, "The Biomechanics of Head Trauma and the Development of the Modern Helmet. How Far Have We Really Come?" Proceedings of the International Research Council on the Biomechanics of Injury conference, vol. 33, 2005. http://www.ircobi.org/wordpress/downloads/irc0111/2005/BertilAldmanLecture/01.pdf (Accessed Nov. 5, 2023)
  6. ↑ 6.0 6.1 6.2 A. E. Eltorai et al., “Federally mandating motorcycle helmets in the United States,” BMC Public Health, vol. 16, no. 1, 2016. doi:10.1186/s12889-016-2914-3
  7. ↑ N. F. Maartens, A. D. Wills, and C. B. T. Adams, “Lawrence of Arabia, sir Hugh Cairns, and the origin of motorcycle helmets,” Neurosurgery, vol. 50, no. 1, pp. 176–180, 2002. doi:10.1227/00006123-200201000-00026
  8. ↑ Motor Vehicle Act, RSBC 1996, c 318. https://www.bclaws.gov.bc.ca/civix/document/id/complete/statreg/96318_00 (Accessed Nov. 29, 2023)
  9. ↑ 9.0 9.1 Ministry of Public Safety and Solicitor General, “Motorcycle safety - the rider and the gear,” Province of British Columbia, https://www2.gov.bc.ca/gov/content/transportation/driving-and-cycling/road-safety-rules-and-consequences/motorcycle-safety (accessed Nov. 29, 2023).
  10. ↑ 10.0 10.1 D.-S. Liu and Y.-T. Chen, “A finite element investigation into the impact performance of an open-face motorcycle helmet with ventilation slots,” Applied Sciences, vol. 7, no. 3, p. 279, 2017. doi:10.3390/app7030279
  11. ↑ 11.0 11.1 11.2 11.3 M. Richter et al., “Head injury mechanisms in helmet-protected motorcyclists: Prospective multicenter study,” The Journal of Trauma: Injury, Infection, and Critical Care, vol. 51, no. 5, pp. 949–958, 2001. doi:10.1097/00005373-200111000-00021
  12. ↑ 12.0 12.1 S. Farajzadeh Khosroshahi, U. Galvanetto, and M. Ghajari, “Optimization of the chin bar of a composite-shell helmet to mitigate the Upper Neck Force,” Applied Composite Materials, vol. 24, no. 4, pp. 931–944, 2016. doi:10.1007/s10443-016-9566-4
  13. ↑ 13.0 13.1 13.2 13.3 13.4 13.5 C.-H. Chang, L.-T. Chang, G.-L. Chang, S.-C. Huang, and C.-H. Wang, “Head injury in facial impact—a finite element analysis of Helmet Chin Bar Performance,” Journal of Biomechanical Engineering, vol. 122, no. 6, pp. 640–646, 2000. doi:10.1115/1.1318905
  14. ↑ 14.0 14.1 G. D. Caserta, L. Iannucci, and U. Galvanetto, “Shock absorption performance of a motorbike helmet with honeycomb reinforced liner,” Composite Structures, vol. 93, no. 11, pp. 2748–2759, 2011. doi:10.1016/j.compstruct.2011.05.029
  15. ↑ 15.0 15.1 R. Ramli, J. Oxley, P. Hillard, A. F. Mohd Sadullah, and R. McClure, “The effect of motorcycle helmet type, components and fixation status on facial injury in Klang Valley, Malaysia: A case control study,” BMC Emergency Medicine, vol. 14, no. 1, 2014. doi:10.1186/1471-227x-14-17
  16. ↑ 16.0 16.1 16.2 16.3 X. Yu, I. Logan, I. de Pedro Sarasola, A. Dasaratha, and M. Ghajari, “The protective performance of modern motorcycle helmets under oblique impacts,” Annals of Biomedical Engineering, vol. 50, no. 11, pp. 1674–1688, 2022. doi:10.1007/s10439-022-02963-8
  17. ↑ 17.0 17.1 17.2 17.3 T. Whyte, T. Gibson, R. Anderson, D. Eager, and B. Milthorpe, “Mechanisms of head and neck injuries sustained by helmeted motorcyclists in fatal real-world crashes: Analysis of 47 in-depth cases,” Journal of Neurotrauma, vol. 33, no. 19, pp. 1802–1807, 2016. doi:10.1089/neu.2015.4208
  18. ↑ 18.0 18.1 S. J. Bonin, J. C. Gardiner, A. Onar-Thomas, S. S. Asfour, and G. P. Siegmund, “The effect of motorcycle helmet fit on estimating head impact kinematics from residual liner crush,” Accident Analysis & Prevention, vol. 106, pp. 315–326, 2017. doi:10.1016/j.aap.2017.06.015
  19. ↑ S. Farajzadeh Khosroshahi, R. Olsson, M. Wysocki, M. Zaccariotto, and U. Galvanetto, “Response of a helmet liner under biaxial loading,” Polymer Testing, vol. 72, pp. 110–114, 2018. doi:10.1016/j.polymertesting.2018.10.012
  20. ↑ G.-J. Park et al., “Protective effect of helmet use on cervical injury in motorcycle crashes: A case–control study,” Injury, vol. 50, no. 3, pp. 657–662, 2019. doi:10.1016/j.injury.2019.01.030
  21. ↑ 21.0 21.1 A. L. DeMarco, D. D. Chimich, J. C. Gardiner, R. W. Nightingale, and G. P. Siegmund, “The impact response of motorcycle helmets at different impact Severities,” Accident Analysis & Prevention, vol. 42, no. 6, pp. 1778–1784, 2010. doi:10.1016/j.aap.2010.04.019
  22. ↑ C. E. Lopes Albuquerque et al., “How safe is your motorcycle helmet?,” Journal of Oral and Maxillofacial Surgery, vol. 72, no. 3, pp. 542–549, 2014. doi:10.1016/j.joms.2013.10.017
  23. ↑ 23.0 23.1 23.2 M. A. Cini, B. G. Prado, P. de Hinnig, W. Y. Fukushima, and F. Adami, “Influence of type of helmet on facial trauma in motorcycle accidents,” British Journal of Oral and Maxillofacial Surgery, vol. 52, no. 9, pp. 789–792, 2014. doi:10.1016/j.bjoms.2014.05.006
  24. ↑ 24.0 24.1 T. M. Rice, L. Troszak, T. Erhardt, R. B. Trent, and M. Zhu, “Novelty helmet use and motorcycle rider fatality,” Accident Analysis & Prevention, vol. 103, pp. 123–128, 2017. doi:10.1016/j.aap.2017.04.002
  25. ↑ 25.0 25.1 25.2 E. M. Urréchaga et al., “Full-face motorcycle helmets to reduce injury and death: A systematic review, meta-analysis, and practice management guideline from the Eastern Association for the surgery of trauma,” The American Journal of Surgery, vol. 224, no. 5, pp. 1238–1246, 2022. doi:10.1016/j.amjsurg.2022.06.018
  26. ↑ Chaichan S, Asawalertsaeng T, Veerapongtongchai P, Chattakul P, Khamsai S, Pongkulkiat P, Chotmongkol V, Limpawattana P, Chindaprasirt J, Senthong V, Ngamjarus C, Sittichanbuncha Y, Kitkhuandee A, Sawanyawisuth K. Are full-face helmets the most effective in preventing head and neck injury in motorcycle accidents? A meta-analysis. Prev Med Rep. 2020 May 13;19:101118. doi: 10.1016/j.pmedr.2020.101118. PMID: 32509508; PMCID: PMC7264075.
  27. ↑ Cosimo Lucci, Simone Piantini, Giovanni Savino & Marco Pierini (2021) Motorcycle helmet selection and usage for improved safety: A systematic review on the protective effects of helmet type and fastening, Traffic Injury Prevention, 22:4, 301-306, DOI: 10.1080/15389588.2021.1894640
  28. ↑ J. Lloyd, "Motorcycle Helmet Injury Biomechanics | Head and Brain Injury," Dr. John Lloyd, 2017 https://drbiomechanics.com/motorcycle-helmet-biomechanics/ (Accessed Nov. 5, 2023)
  29. ↑ 29.0 29.1 29.2 29.3 M. Hitosugi, A. Shigeta, A. Takatsu, T. Yokoyama, and S. Tokudome, “Analysis of fatal injuries to motorcyclists by helmet type,” American Journal of Forensic Medicine & Pathology, vol. 25, no. 2, pp. 125–128, 2004. doi:10.1097/01.paf.0000127397.67081.f5
  30. ↑ 30.0 30.1 30.2 Nat’l Highway Traffic Safety Admin., DOT. Authenticated US Government Information, GPO. 2007. pp. 817–833.
  31. ↑ 31.0 31.1 31.2 Foundation, Snell (11/01/2023). "2025D Standard for Protective Head Gear" (PDF). Snell Memorial Foundation. Retrieved 03/12/2023. Check date values in: |access-date=, |date= (help)
  32. ↑ 32.0 32.1 “ECE 22.05 and 22.06 certification helmets,” Fortamoto, https://www.fortamoto.com/motorcycle-helmets/ece-approval/ (accessed Dec. 4, 2023).
  33. ↑ 33.0 33.1 33.2 33.3 Agreement - ECE Addendum 21: Regulation No. 22 Revision 4, https://unece.org/fileadmin/DAM/trans/main/wp29/wp29regs/r022r4e.pdf (accessed Dec. 4, 2023).
  34. ↑ 34.0 34.1 34.2 34.3 34.4 “Federal Motor Vehicle Safety Standards; Motorcycle Helmets,” The Federal Register , https://www.federalregister.gov/documents/2015/05/21/2015-11756/federal-motor-vehicle-safety-standards-motorcycle-helmets (accessed Dec. 1, 2023).
  35. ↑ 35.0 35.1 35.2 35.3 35.4 35.5 S. Meng, "Towards improved motorcycle helmet test methods for head impact protection Using experimental and numerical methods," Thesis, 2019. https://www.diva-portal.org/smash/get/diva2:1362393/FULLTEXT01.pdf (Accessed Nov 4, 2023)
  36. ↑ S. J. Bonin et al., “Dynamic response and residual helmet liner crush using cadaver heads and standard headforms,” Annals of Biomedical Engineering, vol. 45, no. 3, pp. 656–667, 2016. doi:10.1007/s10439-016-1712-5
  37. ↑ 37.0 37.1 37.2 R. Ramli and J. Oxley, “Motorcycle helmet fixation status is more crucial than helmet type in providing protection to the head,” Injury, vol. 47, no. 11, pp. 2442–2449, 2016. doi:10.1016/j.injury.2016.09.022
  38. ↑ S. Shankar, R. Nithyaprakash, S. Praveen, S. Sathish Kumar, and A. M. Sriram, “Analysis of Motor Cycle helmet under static and dynamic conditions considering different materials,” Materials Today: Proceedings, vol. 43, pp. 1098–1102, 2021. doi:10.1016/j.matpr.2020.08.327
  39. ↑ P. Mohan et al., LSTC/NCAC Dummy Model Development presented at the 11th International LS-Dyna Users Conference, 2010. Accessed: Dec. 03, 2023. [Online]. Available: https://lsdyna.ansys.com/wp-content/uploads/attachments/OccupantSafety-5.pdf
  40. ↑ U.S. Department of Transportation, National Highway Traffic Safety Administration, “Biofidelity Report of the THOR 5th Percentile Anthropomorphic Test Device,” 2020. Accessed: Dec. 04, 2023. [Online]. Available: https://rosap.ntl.bts.gov/view/dot/53629/dot_53629_DS1.pdf
  41. ↑ W. N. Hardy et al., “A Study of the Response of the Human Cadaver Head to Impact,” SAE Technical Paper Series, no. 51, Oct. 2007, doi: https://doi.org/10.4271/2007-22-0002.


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