# US 2021/0172829 A1 · Device for analyzing sensitivity of object using frequency response and analyzing method using the same

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 2021/0172829 A1
- Document ID: US20210172829A1
- Status: Published application
- Kind: A1
- Application number: 16/778,829
- Filed: 2020-01-31
- Published: 2021-06-10
- Earliest claimed: 2019-12-04
- Assignees: Pukyong National University Industry-University Cooperation Foundation
- Applicants: Pukyong National University Industry-University Cooperation Foundation
- Inventors: Chan Jung KIM
- Web page: https://patentgrep.com/patent/US20210172829A1

## CPC

- G01M 7/025: {Measuring arrangements}
- G01H 1/00: Measuring {characteristics of} vibrations in solids by using direct conduction to the detector (G01H9/00, G01H11/00 take precedence)
- G01H 13/00: Measuring resonant frequency
- G01M 7/022: {Vibration control arrangements, e.g. for generating random vibrations}
- G01R 23/16: Spectrum analysis; Fourier analysis
- G01M: TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01H: MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)

## Abstract

Disclosed are a sensitivity analyzing device using a frequency response and a sensitivity analyzing method using the same. The device includes a vibration exciter configured to configure a vibration exciting pattern and apply a physical force to one face of a test object based on the vibration exciting pattern; a first sensor in contact with the one face of the test object to measure a physical force applied to the test object by the vibration exciter; a second sensor in contact with an opposite face of the test object to the one face to collect a vibration of the test object caused by the physical force; and a sensitivity analyzer configured to: control the vibration exciter to configure the vibration exciting pattern; convert the physical force signal measured by the first sensor and the vibration signal collected by the second sensor in responses to the vibration exciting pattern into frequency domain signals to calculate a frequency response function of the test object; and calculate a sensitivity index of the test object to a variation in a physical external force, based on the frequency response function.

## Claims

### Claim 1

A sensitivity analyzing device using frequency response, the device comprising:
a vibration exciter configured to configure a vibration exciting pattern and apply a physical force to one face of a test object based on the vibration exciting pattern;
a first sensor in contact with the one face of the test object to measure a physical force applied to the test object by the vibration exciter;
a second sensor in contact with an opposite face of the test object to the one face to collect a vibration of the test object caused by the physical force; and
a sensitivity analyzer configured to:
control the vibration exciter to configure the vibration exciting pattern;
convert the physical force signal measured by the first sensor and the vibration signal collected by the second sensor in responses to the vibration exciting pattern into frequency domain signals to calculate a frequency response function of the test object; and
calculate a sensitivity index of the test object to a variation in a physical external force, based on the frequency response function.

### Claim 2 (depends on 1)

The sensitivity analyzing device of claim 1, wherein the vibration exciter is configured to apply the physical force based on at least two vibration exciting patterns, wherein the at least two vibration exciting pattern include a random pattern and a harmonic pattern having the same frequency band.

### Claim 3 (depends on 1)

The sensitivity analyzing device of claim 1, wherein the vibration exciter includes an actuator, an electrodynamic shaker or an impact hammer.

### Claim 4 (depends on 1)

The sensitivity analyzing device of claim 1, wherein the first sensor includes a load sensor positioned between the vibration exciter and the test object to measure the physical force.

### Claim 5 (depends on 1)

The sensitivity analyzing device of claim 1, wherein the second sensor includes an acceleration sensor, wherein the second sensor includes a plurality of second sensors mounted on the opposite face of the test object to collect vibrations at a plurality of positions thereon.

### Claim 6 (depends on 1)

The sensitivity analyzing device of claim 1, wherein the test object is made of a material having a single orientation of a predefined angle.

### Claim 7 (depends on 6)

The sensitivity analyzing device of claim 6, wherein the test object is made of a carbon fiber reinforced plastic (CFRP) having carbon fibers as a reinforced material.

### Claim 8 (depends on 6)

The sensitivity analyzing device of claim 6, wherein the sensitivity analyzer is configured to calculate the frequency response function based on a frequency spectrum pattern of the physical force applied to the test object and the orientation angle of the material thereof.

### Claim 9 (depends on 8)

The sensitivity analyzing device of claim 8, wherein the sensitivity analyzer is configured to calculate the frequency response function using a following Equation 1:
H

(
ω
,
θ
,
p
)
=
∑
i
=
1
N

R
i
e
-
ω
2
+
2

ω
n
,
i

(
θ
)

ωξ
i

(
θ
,
p
)

j
+
ω
n
,
i

(
θ
)
2
[
Equation


1
]
where H(ω, θ, p) denotes the frequency response function, θ denotes the orientation angle, p denotes the frequency spectrum pattern, ωn,i(θ) denotes a resonance frequency, ξi(p, θ) denotes a damping ratio, Rie denotes an i-th mode residue, and ω denotes a frequency (=2πf).

### Claim 10 (depends on 6)

The sensitivity analyzing device of claim 6, wherein the sensitivity analyzer is configured to calculate a sensitivity index based on a frequency spectrum pattern of the physical force applied to the test object and a sensitivity index based on the orientation angle.

### Claim 11 (depends on 10)

The sensitivity analyzing device of claim 10, wherein the sensitivity analyzer is configured to calculate the sensitivity index based on the frequency spectrum pattern of the physical force based on a following Equation 2:
I
p
,
i

(
k
)
=

0.5
H

(
ω
,
θ
,
p
)

∂
(
H

(
ω
,
θ
,
p
)
)
∂
p

=

ωω
n
,
i

(
θ
)

∂
(
ξ
i

(
θ
,
p
)
)
∂
p

[
Equation


2
]
where p denotes the frequency spectrum pattern, and Ip,i(k) denotes the sensitivity index based on the frequency spectrum pattern for an i-th mode frequency response function of a k-th test object specimen.

### Claim 12 (depends on 10)

The sensitivity analyzing device of claim 10, wherein the sensitivity analyzer is configured to calculate the sensitivity index based on the angle using a following Equation 3:
I
θ
,
i

(
k
)
=

0.5
H

(
ω
,
θ
,
p
)

∂
(
H

(
ω
,
θ
,
p
)
)
∂
θ

=

ω
n
,
i

(
θ
)

∂
(
ω
n
,
i

(
θ
)
)
∂
θ
+
ω

(
ξ
i

(
θ
,
p
)

∂
(
ω
n
,
i

(
θ
)
)
∂
θ
+
ω
n
,
i

(
θ
)

∂
(
ξ
i

(
θ
,
p
)
)
∂
θ
)

j

[
Equation


11
]
where θ denotes the orientation angle and Iθ,i(k) denotes the sensitivity index based on the angle for an i-th mode frequency response function of a k-th test object specimen.

### Claim 13 (depends on 10)

The sensitivity analyzing device of claim 10, wherein the sensitivity analyzer is configured to:
calculate a first sensitivity index of each of at least two test objects having different orientation angles of the material, based on a frequency spectrum pattern of the physical force applied thereto;
calculate a second sensitivity index of each of the at least two test objects, based on the orientation angle; and
calculate first and second scaled sensitivity indexes of each of the at least two test objects, based on the first and second sensitivity indexes of each test object respectively.

### Claim 14 (depends on 13)

The sensitivity analyzing device of claim 13, wherein the sensitivity analyzer is configured to calculate the first and second scaled sensitivity indexes of each test object based on a following Equation 4:
I
~
θ
,
i
=
I
θ
,
i

(
k
)
∑
k
=
1
3

I
θ
,
i

(
k
)


I
~
p
,
i
=
I
p
,
i

(
k
)
∑
k
=
1
3

I
p
,
i

(
k
)
[
Equation


4
]
where θ denotes the orientation angle, p denotes the frequency spectrum pattern, Ĩθ,i denotes the second scaled sensitivity index based on the angle θ, and Ĩp,i denotes the first scaled sensitivity index based on the frequency spectrum pattern p.

### Claim 15

A sensitivity analyzing method using frequency response, the method comprising:
configuring, by a vibration exciter, a vibration exciting pattern under control thereof by a sensitivity analyzer;
applying, by the vibration exciter, a physical force to one face of a test object based on the vibration exciting pattern;
measuring, by a first sensor, a physical force applied to the test object by the vibration exciter;
collecting, by a second sensor, a vibration of the test object caused by the physical force;
converting, by the sensitivity analyzer, the physical force signal measured by the first sensor and the vibration signal collected by the second sensor in responses to the vibration exciting pattern into frequency domain signals to calculate a frequency response function of the test object; and
calculating, by the sensitivity analyzer, a sensitivity index of the test object to a variation in a physical external force, based on the frequency response function.

### Claim 16 (depends on 15)

The sensitivity analyzing method of claim 15, wherein applying the physical force includes applying the physical force based on at least two vibration exciting patterns, wherein the at least two vibration exciting pattern include a random pattern and a harmonic pattern having the same frequency band.

### Claim 17 (depends on 15)

The sensitivity analyzing method of claim 15, wherein the test object is made of a material having a single orientation of a predefined angle.

### Claim 18 (depends on 17)

The sensitivity analyzing method of claim 17, wherein calculating the frequency response function includes calculating the frequency response function based on a frequency spectrum pattern of the physical force applied to the test object and the orientation angle of the material thereof.

### Claim 19 (depends on 18)

The sensitivity analyzing method of claim 18, wherein calculating the frequency response function includes calculating the frequency response function using a following Equation 1:
H

(
ω
,
θ
,
p
)
=
∑
i
=
1
N

R
i
e
-
ω
2
+
2

ω
n
,
i

(
θ
)

ωξ
i

(
θ
,
p
)

j
+
ω
n
,
i

(
θ
)
2
[
Equation


1
]
where H(ω, θ, p) denotes the frequency response function, θ denotes the orientation angle, p denotes the frequency spectrum pattern, ωn,i(θ) denotes a resonance frequency, ξi(p, θ) denotes a damping ratio, Rie denotes an i-th mode residue, and ω denotes a frequency (=2πf).

### Claim 20 (depends on 17)

The sensitivity analyzing method of claim 17, wherein calculating the sensitivity index includes calculating a sensitivity index based on a frequency spectrum pattern of the physical force applied to the test object and a sensitivity index based on the orientation angle.

### Claim 21 (depends on 20)

The sensitivity analyzing method of claim 20, wherein calculating the sensitivity index based on the frequency spectrum pattern of the physical force includes calculating the sensitivity index based on the frequency spectrum pattern of the physical force based on a following Equation 2:
I
p
,
i

(
k
)
=

0.5
H

(
ω
,
θ
,
p
)

∂
(
H

(
ω
,
θ
,
p
)
)
∂
p

=

ωω
n
,
i

(
θ
)

∂
(
ξ
i

(
θ
,
p
)
)
∂
p

[
Equation


2
]
where p denotes the frequency spectrum pattern, and Ip,i(k) denotes the sensitivity index based on the frequency spectrum pattern for an i-th mode frequency response function of a k-th test object specimen.

### Claim 22 (depends on 20)

The sensitivity analyzing method of claim 20, wherein calculating the sensitivity index based on the angle includes calculating the sensitivity index based on the angle using a following Equation 3:
I
θ
,
i

(
k
)
=

0.5
H

(
ω
,
θ
,
p
)

∂
(
H

(
ω
,
θ
,
p
)
)
∂
θ

=

ω
n
,
i

(
θ
)

∂
(
ω
n
,
i

(
θ
)
)
∂
θ
+
ω

(
ξ
i

(
θ
,
p
)

∂
(
ω
n
,
i

(
θ
)
)
∂
θ
+
ω
n
,
i

(
θ
)

∂
(
ξ
i

(
θ
,
p
)
)
∂
θ
)

j

[
Equation


3
]
where θ denotes the orientation angle and Iθ,i(k) denotes the sensitivity index based on the angle for an i-th mode frequency response function of a k-th test object specimen.

### Claim 23 (depends on 15)

The sensitivity analyzing method of claim 15, wherein the method further comprises:
calculating a first sensitivity index of each of at least two test objects having different orientation angles of the material, based on a frequency spectrum pattern of the physical force applied thereto;
calculating a second sensitivity index of each of the at least two test objects, based on the orientation angle; and
calculating first and second scaled sensitivity indexes of each of the at least two test objects, based on the first and second sensitivity indexes of each test object respectively.

### Claim 24 (depends on 23)

The sensitivity analyzing method of claim 23, wherein calculating the first and second scaled sensitivity indexes of each of the at least two test objects includes calculating the first and second scaled sensitivity indexes of each test object based on a following Equation 4:
I
~
θ
,
i
=
I
θ
,
i

(
k
)
∑
k
=
1
3

I
θ
,
i

(
k
)


I
~
p
,
i
=
I
p
,
i

(
k
)
∑
k
=
1
3

I
p
,
i

(
k
)
[
Equation


4
]
where θ denotes the orientation angle, p denotes the frequency spectrum pattern, Ĩθ,i denotes the second scaled sensitivity index based on the angle θ, and Ĩp,i denotes the first scaled sensitivity index based on the frequency spectrum pattern p.