# Modal Identification in an Automotive Multi-Component System Using HS 3D-DIC

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## Abstract

**:**

## 1. Introduction

## 2. Materials and Method

#### 2.1. Experimental Set-Up

#### 2.2. Transmissibility Functions Using HS 3D-DIC

#### 2.3. Procedure for Modal Identification in Base Motion Tests Using the Circle-Fit Approach

_{exp}represents the transmissibility functions obtained experimentally with the adopted setup.

_{0}. As a result of performing circle fitting in H

_{0}, the actual natural frequency is obtained since ${\mathsf{\omega}}_{\mathrm{n},0}$, scales the function but does not modify the shape. Thus, no additional iteration is required and the actual FRF, H, can be obtained as

## 3. Results

## 4. Conclusions

## Acknowledgments

## Author Contributions

## Conflicts of Interest

## Appendix

**Figure A1.**Non-dimensional FRF of a SDOF system with a structural damping of 0.06 represented (

**a**) in magnitude and (

**b**) in the complex plane.

**Figure A2.**FRF plotted in the complex plane to show the relation between modal and geometrical parameters.

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**Figure 2.**Experimental setup. General arrangement and local zoom on the accelerometer to register excitation.

**Figure 3.**(

**a**) Headlamp view from the right-hand camera; (

**b**) three-dimensional digitalization of the headlamp using HS 3D-DIC in an unforced state. Areas of interest are shown in color: left area of the bezel (white), main reflector (red), bulbshield (green), right area of the bezel (blue), and TI reflector (yellow).

**Figure 4.**The three first PRFs calculated from transmissibility functions in terms of relative displacements for the different components analyzed in this study: (

**a**) right area of the bezel; (

**b**) left area of the bezel; (

**c**) turn indicator reflector; (

**d**) main reflector; and (

**e**) bulbshield. Natural frequencies are indicated as vertical dashed lines.

**Figure 5.**Normalized first mode shape. (

**a**) X displacements with amplitude 0.2023; (

**b**) Y displacements with amplitude 1; and (

**c**) Z displacements with amplitude 0.8014.

**Figure 6.**Normalized second mode shape. (

**a**) X displacements with amplitude 0.4948; (

**b**) Y displacements with amplitude 0.4479; and (

**c**) Z displacements with amplitude 1.

**Figure 7.**Normalized third mode shape. (

**a**) X displacements with amplitude 0.8066; and (

**b**) Y displacements with amplitude 1.

**Figure 8.**Normalized fourth mode shape. (

**a**) X displacements with amplitude 0.5401; and (

**b**) Y displacements with amplitude 1.

**Figure 9.**Normalized fifth mode shape. (

**a**) X displacements with amplitude 0.6316; and (

**b**) Y displacements with amplitude 1.

Element | Material |
---|---|

Bezel | Polycarbonate |

Main reflector | Thermoset BMC |

TI reflector | Polycarbonate |

Bulbshield | Sheet metal steel |

**Table 2.**Natural frequencies and structural damping ratio of the five modes of the multi-component system.

Mode | Natural Frequency (Hz) | Structural Damping (%) | ||||
---|---|---|---|---|---|---|

Bezel’s Right Area | Bezel’s left Area | TI Reflector | Main Reflector | Bulbshield | ||

1 | 43.92 | 8.17 | 6.68 | 8.38 | 7.68 | 7.87 |

2 | 60.56 | 6.24 | - | - | 6.61 | 1.14 |

3 | 73.45 | - | - | - | 7.97 | 8.18 |

4 | 83.42 | - | 3.72 | - | 6.88 | 3.42 |

5 | 93.68 | 5.98 | 6.24 | 4.99 | 4.76 | 7.95 |

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**MDPI and ACS Style**

Molina-Viedma, Á.J.; López-Alba, E.; Felipe-Sesé, L.; Díaz, F.A. Modal Identification in an Automotive Multi-Component System Using HS 3D-DIC. *Materials* **2018**, *11*, 241.
https://doi.org/10.3390/ma11020241

**AMA Style**

Molina-Viedma ÁJ, López-Alba E, Felipe-Sesé L, Díaz FA. Modal Identification in an Automotive Multi-Component System Using HS 3D-DIC. *Materials*. 2018; 11(2):241.
https://doi.org/10.3390/ma11020241

**Chicago/Turabian Style**

Molina-Viedma, Ángel Jesús, Elías López-Alba, Luis Felipe-Sesé, and Francisco A. Díaz. 2018. "Modal Identification in an Automotive Multi-Component System Using HS 3D-DIC" *Materials* 11, no. 2: 241.
https://doi.org/10.3390/ma11020241