Design Validation and Improvement Study of HVAC
Plumbing Line Assembly under Random Loading Condition
Automotive OEMs are currently addressing faster product development cycle needs with increasingly rob
validation processes facilitated by improved CAE tools and techniques. This includes developing reliable virtual methods for problems. The objective of this paper is to present a validation process for HVAC Plumbing line A
loading condition for a specific test setup. The process is validated by correlating virtual the plumbing line to the corresponding observations in physical test. The method is th virtual models to address and mitigate the problem
currently developed on HyperWorks platform (version 11.0)
Introduction:
The purpose of the HVAC plumbing assembly is to provide a reliable leak
transferring refrigerant and oil between air conditioning components at high and low temperatures and pressures. HVAC Plumbing shall be routed and supported
life cycle of the product. HVAC Plumbing must be routed so as to either be sufficiently constrained or have sufficient clearance with surrounding components to prevent harmful contact.
Suction Line-Tube that convey refrigerant gas or vapor from evaporator outlet to the suction inlet compressor.
Discharge Line – Tube that convey the compressed refrigerant vapor from compressor to the condenser inlet.
Liquid Line – Tube used to convey liquid refrigerant from the device of evaporator.
Rakesh Jakhwal
Senior Engineer Chrysler Group LLC RMZ Millenia II, Perungudi
Chennai 600096, India
RMZ Mi
Design Validation and Improvement Study of HVAC
Line Assembly under Random Loading Condition
Abstract
Automotive OEMs are currently addressing faster product development cycle needs with increasingly rob
validation processes facilitated by improved CAE tools and techniques. This includes developing reliable virtual methods for problems. The objective of this paper is to present a validation process for HVAC Plumbing line Assembly under random vibration loading condition for a specific test setup. The process is validated by correlating virtual prediction of potential problems
the plumbing line to the corresponding observations in physical test. The method is then used to develop design modifications in the address and mitigate the problem which is then verified in the physical re-test. The virtual methodology has be
orks platform (version 11.0).
plumbing assembly is to provide a reliable leak-free and efficient method of transferring refrigerant and oil between air conditioning components at high and low temperatures and
Plumbing shall be routed and supported in a manner which ensures functionality du Plumbing must be routed so as to either be sufficiently constrained or have sufficient clearance with surrounding components to prevent harmful contact.
onvey refrigerant gas or vapor from evaporator outlet to the suction inlet
Tube that convey the compressed refrigerant vapor from compressor to the condenser
Tube used to convey liquid refrigerant from the condenser outlet to the refrig
Yogesh Kumar
Senior Engineer Chrysler Group LLC RMZ Millenia II, Perungudi
Chennai 600096, India
Muthukumar
Manager Chrysler Group LLC RMZ Millenia II, Perungudi
Chennai 600096, India
1
Design Validation and Improvement Study of HVAC
Line Assembly under Random Loading Condition
Automotive OEMs are currently addressing faster product development cycle needs with increasingly robust and efficient virtual validation processes facilitated by improved CAE tools and techniques. This includes developing reliable virtual methods for complex ssembly under random vibration prediction of potential problems locations on en used to develop design modifications in the test. The virtual methodology has been
free and efficient method of transferring refrigerant and oil between air conditioning components at high and low temperatures and in a manner which ensures functionality during Plumbing must be routed so as to either be sufficiently constrained or have
onvey refrigerant gas or vapor from evaporator outlet to the suction inlet
Tube that convey the compressed refrigerant vapor from compressor to the condenser
condenser outlet to the refrigerant control
Muthukumar Arunachalam
Manager Chrysler Group LLC RMZ Millenia II, Perungudi
Figure 1: Plumbing line routing
An automobile traveling down a rough road is subjected to random excitation. The Random vibration test verifies the components capability to
exposure to the service life random vibration environments. Real world vibrations are usually of the random type.
Figure 2: (a) sine wave
The difference between sine vibration and random vibration is that for random vibration, at any point in time, any frequency can be happening that will excite, or resonate, multiple bodies at once. What this means is although one member of the system
resonating at the same instant in a random vibration environment. The sine environment will run the input curve over the frequency band from 20 to 2000 hertz that can be experienced in the vehicle and only on member will resonate at a time, assuming of course two members do not share a natural frequency. Most of the time a sine scan is run to determine the resonances of the vehicle. A 1G input over the entire frequency band is used, and is not meant to induce
certification or qualification testing occurs.
Figure 1: Plumbing line routing sketch diagram
An automobile traveling down a rough road is subjected to random excitation. The Random vibration test verifies the components capability to meet applicable functional/performance requirement during or after exposure to the service life random vibration environments. Real world vibrations are usually of the random
(b) Random profile (c) PSD curve
erence between sine vibration and random vibration is that for random vibration, at any point in time, any frequency can be happening that will excite, or resonate, multiple bodies at once. What this means is
ber of the system may have a low frequency, and another
resonating at the same instant in a random vibration environment. The sine environment will run the input curve over the frequency band from 20 to 2000 hertz that can be experienced in the vehicle and only on member will resonate at a time, assuming of course two members do not share a natural frequency. Most of the time a sine scan is run to determine the resonances of the vehicle. A 1G input over the entire frequency band is used, and is not meant to induce fatigue damage. This data is used to validate the FEA before certification or qualification testing occurs.
An automobile traveling down a rough road is subjected to random excitation. The Random vibration test meet applicable functional/performance requirement during or after exposure to the service life random vibration environments. Real world vibrations are usually of the random
(c) PSD curve
erence between sine vibration and random vibration is that for random vibration, at any point in time, any frequency can be happening that will excite, or resonate, multiple bodies at once. What this means is w frequency, and another high, they can both be resonating at the same instant in a random vibration environment. The sine environment will run the input curve over the frequency band from 20 to 2000 hertz that can be experienced in the vehicle and only one member will resonate at a time, assuming of course two members do not share a natural frequency. Most of the time a sine scan is run to determine the resonances of the vehicle. A 1G input over the entire frequency fatigue damage. This data is used to validate the FEA before
Sigma (σ) & Sigma Clipping:
Sigma is the standard deviation of a statistical PDF. vibration which takes the shape of a bell shaped curve.
vibration will change over time, the time spent at different amplitude excursions is measured using a PDF. Figure 3 shows a Gaussian PDF.
is the mean which is equal to zero for a shaker control.
excursions occur between ± 1 sigma, 95.4% between ± 2 sigma, 99.7% between ±
Process Methodology:
Figure 4:
Figure 3: sigma clipping
Sigma is the standard deviation of a statistical PDF. A Gaussian PDF distribution is assumed for random vibration which takes the shape of a bell shaped curve. Since the amplitude or intensity
vibration will change over time, the time spent at different amplitude excursions is measured using a PDF. The vertical axis would be 1/G, the horizontal axis would be sigma and µ zero for a shaker control. For a Gaussian distribution, 68.2% of the peak G excursions occur between ± 1 sigma, 95.4% between ± 2 sigma, 99.7% between ± 3
Figure 4: HVAC Plumbing line Validation Process
3 A Gaussian PDF distribution is assumed for random Since the amplitude or intensity of the random vibration will change over time, the time spent at different amplitude excursions is measured using a PDF. The vertical axis would be 1/G, the horizontal axis would be sigma and µ For a Gaussian distribution, 68.2% of the peak G
Physical Test Setup:
Test set up placed in a group of 4-6 samples to be tested in tri location as per vehicle condition
.
Generic random vibration profile as per
Figure 5 Performance Criteria:
Vibration testing shall be performed with plumbing line assembly installed in bench test condition. The acceptance criteria are:
- No issues, Leak Test prior to the vib - No issues (cracks, deformation, etc.) of add
service valves, etc., following evaluation, Florescent Liquid Penetrate Inspection.
CAE process and correlation:
Meshing -AC plumbing line FE modeling is done as per
Boundary Condition -Plumbing Line is constrained as per Physical Test shown above. Analysis -Modal analysis is performed to check the natural frequency of the p followed by random vibration anal
sigma stress is higher than the material yield stress.
Figure
6 samples to be tested in tri - axial shaker table with bolted with the ibration profile as per standard provided to run specific hours for each individual axis.
5: Controlled input PSD profiles for shaker table
Vibration testing shall be performed with plumbing line assembly installed in bench test condition. , Leak Test prior to the vibration test for each axis for specifichrs. cycle run.
s (cracks, deformation, etc.) of add-on components such as brackets, clips, isolators, transducer, service valves, etc., following evaluation, Florescent Liquid Penetrate Inspection.
AC plumbing line FE modeling is done as per standard guidelines.
Plumbing Line is constrained as per Physical Test shown above. Modal analysis is performed to check the natural frequency of the p
followed by random vibration analysis using vehicle road profile. Problem could be predicted when the 3 sigma stress is higher than the material yield stress. Example of which is shown below
Figure 6: CAE – Model Set Up
axial shaker table with bolted with the hours for each individual axis.
Vibration testing shall be performed with plumbing line assembly installed in bench test condition. cycle run.
on components such as brackets, clips, isolators, transducer,
Plumbing Line is constrained as per Physical Test shown above.
Modal analysis is performed to check the natural frequency of the plumbing line assembly, could be predicted when the 3 Example of which is shown below.
Results & Discussions:
Two- Piece bracket design Baseline
Figure 7: Physical and CAE results for baseline bracket CAE simulation correlates well with the Test
bracket. Design Iterations were carried out to avoid problems Physical Test
Problem observed
hours in first axis at marked location
Baseline - 2 pieces Bracket material aluminum.
Piece bracket design Baseline
: Physical and CAE results for baseline bracket
s well with the Test. 3-sigma RMS stress are higher than the Yield stress of the ere carried out to avoid problems with material and gauge change.
Figure 8: Bracket design modification
Physical Test Virtual Test
Problem observed beforespecific hours in first axis at marked location
Maximum 3-sigma RMS stress isobserved more than material yieldstress at marked location
2 pieces Bracket material Proposed
-aluminum with bead. Design Modification
5 higher than the Yield stress of the erial and gauge change.
sigma RMS stress isobserved more than material marked location
- single piece Bracket Material with bead.
CAE proposed- single piece bracket design with bead
Figure 9: CAE and Physical Test Results for Modified Bracket
Benefits Summary:
The random vibration analysis tool
time. It helps to evaluate the performance of a design before cutting tools or physically building The cost of the design verification in the different stages
sample size.
Challenges:
The major challenge with random vib
need to take care for this type of analysis. Extra from road profiles to make PSD curve.
Future Plans:
Current CAE validation using random vibration analysis can be extended to fatigue life prediction which would yield the information of number of cycles.
Conclusions:
It is necessary to take structural loads
and reach a conclusion. Even though there have been many advances in CAE, and it is widely used in the engineering field, physical testing is still used as a final confirmation for subsystems due to the fact that CAE cannot predict all variables in complex assemblies.
Physical Test No issue observed
the test.
single piece bracket design with bead
: CAE and Physical Test Results for Modified Bracket
andom vibration analysis tool reduces the product development phase as virtual tools the performance of a design before cutting tools or physically building
n in the different stages eliminates by reducing number of physical test or
The major challenge with random vibration analysis to solving time and file size is
analysis. Extra care need to be carried for averaging and filtering the data from road profiles to make PSD curve.
idation using random vibration analysis can be extended to fatigue life prediction which would yield the information of number of cycles.
It is necessary to take structural loads due to sine and random environment to define the frequency
though there have been many advances in CAE, and it is widely used in the engineering field, physical testing is still used as a final confirmation for subsystems due to the fact that CAE
complex assemblies.
Physical Test Virtual Test
observed tillspecific hours in the test.
Maximum 3-sigma RMS stress isobserved less than material
yieldstress.
: CAE and Physical Test Results for Modified Bracket
the product development phase as virtual tools consumes less the performance of a design before cutting tools or physically building prototypes. by reducing number of physical test or
ration analysis to solving time and file size is more. Nonlinearity affect care need to be carried for averaging and filtering the data
idation using random vibration analysis can be extended to fatigue life prediction which
define the frequency domain though there have been many advances in CAE, and it is widely used in the engineering field, physical testing is still used as a final confirmation for subsystems due to the fact that CAE
sigma RMS stress than material
We would like to thank the Chrysler
also like to thanks to design and testing team for continuous support
[1] Francis J. Andrews: “Random Vibration –
[2] Tom Irvine : “Power Spectral Density units:[G^2/Hz] Revision A”
[3] Tom Irvine: “An Introduction to Random Vibration Revision B” [4] OptiStruct - 11.0 – reference guide
[5] NWM Bishop: “Vibration Fatigue Analysis In Finite Element Environment”, 1999
ACKNOWLEDGEMENTS
Chrysler Management for their continuous support in accomplishing this task and testing team for continuous support to execute the process
REFERENCES – An Overview”
Tom Irvine : “Power Spectral Density units:[G^2/Hz] Revision A”
Random Vibration Revision B”
Vibration Fatigue Analysis In Finite Element Environment”, 1999
7 for their continuous support in accomplishing this task and
