title: Factors influencing the oblique impact test of motorcycle helmets.
abstract: OBJECTIVE
  Oblique impact tests can provide important information regarding the level of protection of a helmet. Two factors that influence the results of oblique impact tests on motorcycle helmets are discussed in this work. The first factor is the angle of the anvil on which the helmet impacts. The second one is the friction between the headform and the helmet's interior.
  
  
  METHODS
  To study the first factor, 2 anvil angles are provided, one 30° and the other one 15° to the vertical. To analyze the second factor, we consider 2 types of headform surfaces: the original metal surface of the standard headform and the same headform covered uniformly with a layer of silicone rubber that is 1 mm thick.
  
  
  RESULTS
  The results show that varying the anvil's angle and surface friction can directly affect the linear and rotational acceleration of the headform.
  
  
  CONCLUSIONS
  Testing helmets for different oblique impact angles can help assess their protection capability. The coefficient of friction between the helmet's interior and the headform plays an important role in the headform's rotational acceleration during an impact. Using a standard surface friction for headform similar or close to that of the human scalp can ensure that the results of the oblique impact tests are more consistent and realistic.
authors.affiliation: a School of Mechatronic Systems Engineering, Simon Fraser University , Surrey , British Columbia , Canada.
authors.forename: Iman
authors.initials: I
authors.lastname: Ebrahimi
authors.forename: Farid
authors.initials: F
authors.lastname: Golnaraghi
authors.forename: G Gary
authors.initials: GG
authors.lastname: Wang
mesh_terms: D000054:Acceleration; D000063:Accidents, Traffic / Q000706:statistics & numerical data*; D006259:Craniocerebral Trauma / Q000517:prevention & control; D004867:Equipment Design; D006257:Head / Q000502:physiology; D006260:Head Protective Devices; D006801:Humans; D009049:Motorcycles
keywords: linear acceleration; motorcycle helmet; oblique impact; rotational acceleration