Technical Bulletin

Compatibility Assessment
Version 1.1.1

June 2020
TB 027

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Document Number
AuthorDate
Related Documents
StatusApplication Date

Compatibility Assessment
1.1.1
TB 027
James Ellway
June 2020
MPDB Assessment ProtocolInformation
1st January 2020

Copyright ©Euro NCAP 2020 - This work is the intellectual property of Euro NCAP. Permission is granted for thismaterial to be shared for non-commercial, educational purposes, provided that this copyright statement appears on thereproduced materials and notice is given that the copying is by permission of Euro NCAP. To disseminate otherwise orto republish requires written permission from Euro NCAP.

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Preface
In 2020 the European New Car Assessment Programme (Euro NCAP) will be updating its
offset frontal impact test procedure. These updates will be centred on the adoption of theThor anthropometric test device and a new barrier face for the mobile progressive
deformable barrier (MPDB). This Technical Bulletin details the calculation of theCompatibility Assessment.

DISCLAIMER: Euro NCAP has taken all reasonable care to ensure that the information
published in this document is accurate and reflects the technical decisions taken by theorganisation. In the unlikely event that this protocol contains a typographical error or any
other inaccuracy, Euro NCAP reserves the right to make corrections and determine theassessment and subsequent result of the affected requirement(s).

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EUROPEAN NEW CAR ASSESSMENT PROGRAMME (Euro NCAP)

Table of Contents
1.

Introduction ......................................................................................................................... 1

2.

Barrier Deformation Standard Deviation .............................................................................. 2

3.

Occupant Load Criterion ...................................................................................................... 3

4.

Bottoming Out ..................................................................................................................... 4

5.

Calculation........................................................................................................................... 5

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1.

Introduction

The Euro NCAP compatibility assessment is based upon three parameters that aredetermined using the results of the Mobile Progressive Deformable Barrier (MPDB) to car
impact. The three parameters are the standard deviation (SD) of the post-test barrier facemeasurements, the Occupant Load Criterion (OLC) and whether the vehicle has bottomedout the MPDB face. Details on how each of these parameters is determined is illustrated in
the following sections of this document.
From 1st January 2023, the compatibility assessment will be a 0 to 8-point penalty applied
to the overall test score, as described in section 5 in this document. During the introduction
years 2020, 2021 and 2022, the compatibility penalty applied will be halved (maximum 4points).
The penalty for standard deviation and OLC is based on two interlinked sliding scales thatcan cover the full range of the penalty (0 to 8 points) where the lower performance limits
have been exceeded.
Where the OLC is 25g and below, the penalty ranges from 0 to 2 points and is based on SD
only. Where the OLC is 40g and above, the penalty ranges from 2 to 8 points and is basedupon both SD and OLC. Where OLC is between 25g and 40g, the penalty is based upon thetwo sliding scales for SD and OLC.
Bottoming out is an additional 2 point penalty that is added to the modifier calculated fromthe combination of SD and OLC. The maximum compatibility assessment will not exceed
8 points.

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2.

Barrier Deformation Standard Deviation

2.1

The homogeneity of the vehicle is based on the standard deviation of the intrusion
depth within the prescribed measurement area of the MPDB face.
The standard deviation is defined as the spread around the mean intrusion thatcovers 68.2% of all measured intrusion points. The bigger the standard deviation,
the bigger the spread of the measured intrusion points.
The assessment of SD is based on a linear scale from 50mm to 150mm where 50mm
is the higher performance limit and 150mm is the lower performance limit.

2.2

2.3

2.4
2.4.1

2.4.2

2.4.3

Evaluation area
The height of the evaluation area is independent of vehicle size. The lower borderis at 250mm above ground level (100mm from the lower edge of the barrier face).
The upper border is at 650mm above the ground of the MPDB face.
For a left-hand drive vehicle, the right border of the area is located at 200mm fromthe right-hand edge of the MPDB face. The left border is dependent on the width of
the test vehicle, it is located at 45% of the overall width from the right-hand edgeof the MPDB face. See Figure 1.
The evaluation area for right hand drive vehicles will be mirrored accordingly
around the vertical axis.

Figure 1: Evaluation area

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2.5
2.5.1

Barrier scan data.
Scanning of the barrier face shall be conducted in accordance with the procedure
detailed in the Euro NCAP MPDB testing protocol.
2.5.2 The scanning data shall be inserted into the Euro NCAP Compatibility assessment
spreadsheet in accordance with the following.
2.5.3 All required data shall be filled in the green cells within the sheet “input scan”.
2.5.4 The intrusion depths of the 1400 measuring points that came out of the scanning
process are entered in column F (x-coordinates).
2.5.5 The data shall be entered row by row and top down.
2.5.6 The first measuring point (located top left on the front view of the barrier) shall beentered in line 7.
2.5.7 The last measuring point (located down right on the front view of the barrier) shallbe entered in line 1406.
2.5.8 Within cell F2 the minimum measured intrusion depth is displayed.
2.5.9 Within cell F3 the maximum measured intrusion depth is displayed.
2.5.10 Within the sheet “pattern” the position of the single measuring points are displayed
2.5.11 Within the cell J2 the make and model of the tested vehicle and within the cell K2
the test number should be entered (both types of information are only required torelate the evaluation with a certain test they are not relevant for the SD calculation)
2.5.12 Within the cell L2 the location of the steering wheel (left, or right) must be entered.
This information will be used by the spreadsheet to determine the location of theevaluation area on the surface of the barrier face.
2.5.13 Within the cell M2 the overall width of the test vehicle must be entered. This
information is required to determine the size of the evaluation area on the surfaceof the barrier face.
2.5.14 Within the cell N2 the occurrence of bottoming out (yes or no) must be entered.

3.

Occupant Load Criterion

3.1
3.2

The OLC is evaluated using a sliding scale between 25g and 40g.
Measured X-acceleration (AX) on the centre of gravity of MPDB shall be filteredusing CFC180.
The acceleration from the backup CoG accelerometer shall only be used for theOLC calculation where there is a channel failure of the primary accelerometer.
The acceleration data shall be entered in to the Euro NCAP compatibility
assessment spreadsheet.
The calculation for OLC is as follows:
The filtered acceleration pulse shall be integrated with the following equation toderive the velocity course of the barrier:

3.3
3.4
3.5
3.5.1

𝑉𝑡 = ∫ 𝐴𝑋 (𝑡) 𝑑𝑡 + 𝑉0
3.5.2

Where 𝑉0 is the initial velocity of the barrier at 𝑡 = 0𝑠.
𝑂𝐿𝐶𝑆𝐼−𝑢𝑛𝑖𝑡 , 𝑡1 and 𝑡2 can be calculated with solving the following equation system:

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𝑡=𝑡1

∫𝑡=𝑡1

𝑉0 𝑑𝑡 − ∫𝑡=0𝑡=𝑡2∫

𝑉 (𝑡) 𝑑𝑡 = 0.065

𝑡=0𝑡=𝑡2(𝑉0 − 𝑂𝐿𝐶𝑆𝐼−𝑢𝑛𝑖𝑡 × (𝑡 − 𝑡1 )) 𝑑𝑡 − ∫𝑡=𝑡1

𝑉 (𝑡) 𝑑𝑡 = 0.235

𝑡=𝑡1{𝑉0 − 𝑂𝐿𝐶𝑆𝐼−𝑢𝑛𝑖𝑡 × (𝑡2 − 𝑡1 ) = 𝑉 (𝑡2 )Where:-𝑡1 is end of the free-flight-phase of a virtual dummy on the barrier along adisplacement of 0.065m, and-𝑡2 is end of the restraining-phase of a virtual dummy on the barrier along adisplacement of 0.235m after the free-flight-phase (i.e. in total 0.300m
displacement for the virtual dummy).

3.5.3

For compatibility assessment OLC shall be converted from SI units into g (standardgravity) with the conversion factor of 1g = 9.81m/s²

4.

Bottoming Out

4.1

Bottoming out is defined as an area of the barrier that has been penetrated by630mm or more that is 40mm x 40mm in height and width.
Bottoming out will be determined from a physical examination of the barrier faceand vehicle. This will be evaluated by the Inspectors during the vehicle inspection
and be based upon the barrier scanning results.
Where bottoming out occurs within the evaluation zone, a 2-point penalty will beadded to the barrier deformation and OLC penalty.

4.2

4.3

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5.

Calculation

5.1

The assessment of standard deviation and OLC are both calculated on sliding scales
between their respective limits detailed in Sections 2.2 and 3.1, the bottoming out
penalty is then added to produce the final compatibility assessment.
For SD<50mm, OLC<25g and no bottoming out there will be no penalty.
For SD<50mm, OLC<25g with bottoming out the penalty will be -2.
For SD>150, OLC>40g and no bottoming out the penalty will be -8.
For SD>150, OLC>40g with bottoming out the penalty will be -8.
Where the SD and OLC are between the respective limits, the calculation is based
upon the following percentages:

5.2
5.3
5.4
5.5
5.6

Performance limits
Standard deviation
OLC MPDB
5.7

0%
50mm
25g

20%
70mm
28g

40%
90mm
31g

60%
110mm
34g

80%
130mm
37g

100%
150mm
40g

Figure 2 below is showing the sliding scales and resulting scoring rationale.

Figure 2: General scoring rationale
5.8

According to the above calculation, the maximum value of the modifier is 8 points,
which will be deducted from the total MPDB test score. During the introduction
years, 2020 and 2021, the modifier will be halved, with a maximum of 4 points.

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56.

Examples6.1

Example 1 below is a calculation based on the following results for 2023 onwards:
Standard deviation (homogeneity) = 119mm = 69%
OLC = 34.9g
Bottoming out = NO
Modifier-3.2-1.3-0-4.553

Figure 3: Example 1

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66.2

Example 2 is a calculation based on the following results for 2023 onwards:
Standard deviation (homogeneity) = 140mm = 90%OLC = 37.7g
Bottoming out = YES-4.8-1.7-2

Modifier-8.0

Figure 4: Example 2

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6.3

Example 3 is a calculation based on the following results for 2023 onwards:
Standard deviation (homogeneity) = 100mm = 50%
OLC = 27.2g
Bottoming out = YES
Modifier-1.3-0.3-2-3.587

Figure 5: Example 3

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6.4

Example 4 is a calculation based on the following results for 2020-2022:
Standard deviation (homogeneity) = 140mm = 90%
OLC = 37.7g
Bottoming out = YESModifier

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-4.8
-1.7
-2-8.0*0.5 = -4.09