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Impact biomechanics TME196 > Questions > Flashcards

Flashcards in Questions Deck (26):
1

Why is the criterion HIC considered insufficient. Please describe

a) Skull fractures: In frontal collisions fractures is not the only problem. There is also a risk of brain injury, even without a fracture.

b) Linear only: HIC only consider linear acceleration but also rotational acceleration should be taken into account

c) Impact direction (only frontal impacts), area of contact, stiffness of the impacting surface

2

Why are long bones hollow? / Why are flat bones and some parts of distal bones hollow?

a) Storage of minerals and fat

b) Weight optimization: If the long bone wouldn't be hollow, a lot of extra weight would be added to the skeleton

3

Synovial joints between bones have different degrees of freedom. Sketch 4 joints with different degrees of freedom, give example of where in the body they can be found.

a) plane joints, carpals, 3 DOF
b) Hinge joint, elbow (between Humerus and Ulna), 1 DOF
c) Pivot joint, between Ulna and Radius, 1DOF
d) Condyloid joint, between finger bones (Metacarpal and Phalanx), 2 DOF
e) Saddle joint, thumb (between Carpal and metacarpal #1), 2 DOF
f) Ball-and-socket joint, shoulder, 3 DOF

4

Provide a sketch of the human brain that show 4 anatomical lobes, 2 sulcus and 2 fissures

- Occipital lobe, Parietal lobe, Frontal lobe, Temporal lobe
- Parieto-occipital sulcus, Central sulcus
- Preoccipital notch, Lateral notch

5

The top two vertebrae (closest to the head) are special. Please provide the names of these two and describe their characteristics.

Their names are:
C1 - Atlas
C2 - Axis

- Atlas is special because it doesn't have any spinous process or vertebral body, the vertebral arch goes all the way around.

- Axis doesn't have a spinous process. Axis has a dens which goes into Atlas.

- The combination of Atlas and Axis makes it possible to rotate the head as indicating "no"

6

What are the most important pros and cons with volunteers, PMHSs and animals?

Volunteers:
+ + Proper soft tissue response
+ Gross kinematics from film analysis and instruments
+ Detailed kinematics from high speed x-ray
+ + Muscle response
- Military personnel and students
- Awareness of impact
- - Testing below point of injury
- - Limited age distributions
- No injury data

PHMSs:
+ + Testing to failure
+ + Test isolated body segments: arm, head, leg
+ Local and gross kinematics
- - Limited number: poor possibility to select size, fitness, mostly older people
- - Soft tissue properties varies
- No physiological response: symptoms and soft tissue damage

Animals:
+ Instrumentation of body segments
+ + Intrusive probes
+ Specific physiological response
+ + Testing to injury and beyond
- - Scaling required for transferring the info to human response data
- - Ethical

7

In development of injury risk functions different regression techniques are used. What is the difference between non-parametric model and parametric model?

Non-parametric: No assumptions of the data is made fex that it should follow a certain distribution. Instead the data is plotted as it is.

Parametric: The data is assumed to follow a certain distribution and is then plotted accordingly

8

Bone material has properties dissimilar many of the more common engineering materials. List and explain four important dissimilarities and present why these are important to take into account when modeling bone material

a) Viscoelastic: The response changes with the speed which the load is applied

b) Non-linear: The response is non-linear

c) Anisotropic: The bone have different properties in different directions

d) Non-homogenius: The bone have a composite structure that is complex

9

What are the most important biomechanics differences between adults and children that require special attention when designing child restraints to be used in cars? Describe these differences and how these influence the interaction with restraints during a car collision?

a) Head mass proportions -> head load on neck

b) Head CG height -> neck loads

c) Higher vertebrae flexibility and sheering -> neck injury

d) Chest softer -> internal organ compression, less bone damage

e) Smaller ribcage -> exposed abdomen

f) Smaller iliac wing size -> poor belt interaction in frontal collisions

g) Shorter femur length -> extension of pelvis due to poor belt interaction

10

Provide the names of the bones labeled A through H

A: Parietal
B: Frontal
C: Sphenoid
D: Zygomatic
E: Maxilla
F: Mandible
G: Temporal
H: Occipital

11

Give names to the two muscles that are marked in the two sketches a) Shoulder and b) "Traps"

a) Shoulder: Deltoid
b) "Traps": Trapezius

12

The spine consists of three main groups of vertebra. Provide the names, their numbers, and characteristics

- Cervical, 7, lordotic, low, large flexion and extension, limited lateral bending, some rotation around vertical axis.

- Thoracic, 12, kyphotic, low, limited flexion and extension, very limited lateral bending, and rotation around vertical axis.

- Lumbar, 5, lordotic, large, rather large flexion and extension, limited rotation around vertical axis.

13

In accident data analysis it is common to assess the validity and reliability of the data. Describe these two terms.

- Validity (accuracy to target): The extent to which the study measures what it is intended to measure.
"Are the values describing what was supposed to be measured?"

- Reliability (precision to other measurements): True level of the property being measured.
"Will one get the same values if the measurements are repeated?"

14

Crash test dummies should preferably have anthropometry similar to that of humans. What other properties are important? List and explain six other properties (8 in total)

a) Anthropometry: Shape, size and mass distribution similar to human.

b) Bio-fidelity: The joints and stiffness of dummy similar to human.

c) Sensitivity: The dummy should be sensitive to crash loads.

d) Instrumentation: The dummy should be instrumented by suitable measurement equipment to measure the desired parameters.

e) The dummy should be easy to calibrate before testing to avoid mistakes.

f) Durability: The dummy should not break of fracture during the test.

g) Repeatability: If we repeat the test for several times with one dummy, the result should be the same.

h) Reproducibility: Two dummies should give the same result in identical test conditions.

15

Accident data are commonly, in the field of traffic safety, described based on what is included as being at the macroscopic level, intermediate level and microscopic level. Please describe these three levels and provide the names of one example database per level.

Macroscopic level, statistical data, police:
+ all types of severities
+ "representative" of crashes in the region
- few vehicle specific details
- no detailed injury data
STRADA Police (SWE)
CARE/CADaS (EU)
NASS-GES (US)

Intermediate level, insurance:
+ Relatively low cost
+ Large dataset
- no/little injury causation data
- limited data access
STRADA Hospital (SWE)
Insurance databases

Microscopic level, in-depth data, research:
+ detailed data in vehicle, occupant and infrastructure
+ identify accident causation
+ identify injury causation
- high cost of data collection
- not representative
- limited data access
NASS-CDS (US)
FICA (SWE)
INTACT (SWE)
GIDAS(GER)

16

Describe what the term overuse injury means.

Muscle or joint injury, such as tendinitis or stress fracture, that's caused by repetitive trauma as opposed to acute injuries, which occur in an instant.

17

Describe weighting in NASS-GES. What is the difference if the NASS-data analysis is carried out weighted or unweighted?

- The data is weighted according to how common each individual crash is in the database sample in comparison to how common each crash is in real life.

- A low number means the crash is overrepresented in the database sample in comparison to all data.

- A high number means the crash is more common in reality than it is represented in the database.

- If the analysis is carried out using unweighted data it is only representative of the sample. If it is carried out used weighted data, it represents all crashes.

18

Describe and exemplify how numerical models can be used to improve vehicle safety

a) Cost: The lower cost imply that more tests can be done compared to real life.

b) Sizes: Possibility to scale the HBMs to do tests on a more variant group.

c) Multipel crash scenarios: Possibilities to a wider span of crash scenarios.

d) Early and thereby allow for influencing design changes.

19

What are the major disadvantages using scaling approach presented by Holbourn 1943? What alternatives are available?

The Holbourn require that:
- The brain acts as an elastic medium
- The brain tissue is homogenous
- The brain is isotropic in nature
- The brain has similar properties
- The brain has similar shapes

Alternative is using FE-models of animals for the development of tissue criteria

20

What types of brain injuries are common in traffic accidents? Please categorize these into groups based on location and injury type.

- Focal: Contusion and Hematoma
- Diffuse: Concussion and DAI

21

Describe how an "optimal" bicycle helmet protects the head fein injuries.

- Outer layer from direct contact between structure and skull bone during impact
- Inner layer cushion the impact

22

What other important functions does bones have in addition to carrying load?

a) Protection
b) Movement
c) Carrying load
d) Mineral storage
e) Blood cell formation

23

Describe how a traditional seatbelt protects the occupant from injuries and why it is designed as it is.

- By reducing the force of secondary impacts with interior strike hazards
- By keeping the occupant positioned correctly for maximum effectiveness of the airbag
- By preventing occupants being ejected from the vehicle

Design:
- Diagonal transfer load to the ribcage and clavicle and not to soft body segments.
-Lap belt transfer load to the pelvis bones and not the soft body organs.

24

What other important functions do muscles have in addition to produce force?

- Produce force
- Posture
- Stabilizes
- Heat
- Protection

25

Please provide a sketch of a cervical vertebrae. Label its important parts.

- Body
- Transverse process
- Joint surface of the superior articular process
- Joint surface of the inferior articular process
- Spinous process
- Arch

26

What types of brain injuries are common in traffic accidents? Please explain why these occur.

Common injuries in traffic are:
- Concussion
- DAI
- Hematoma: occur due to fracture but commonly due to blunt trauma.
- Contusion: occur due to brain to skull contact.

- Concussion and DAI occur when the head is exposed to rotational trauma or acceleration, this cause distortion of the brain tissue so that the axons/supporting structures are effected.