researchonimprovementoftruckvibrationbasedonsystematic … · 2019. 7. 30. · researcharticle...

Research ArticleResearchon ImprovementofTruckVibrationBasedonSystematicG8D Method

Hongfei Guo,1,2 Minshi Chen ,2 Ru Zhang,3 Jianke Li,4 Congdong Li ,1,2 Ting Qu,1,2

George Q. Huang,1,2 Zhihui He,1 and Yunhui Zeng2

1Institute of Internet of �ings and Logistics Engineering, Jinan University, Zhuhai 519070, China2Institute of Intelligent Science and Engineering, Jinan University, Zhuhai 519070, China3Institute of Management Science and Engineering, Jinan University, Zhuhai 510970, China4School of Industrial Automation, Beijing Institute of Technology, Zhuhai 519088, China

Correspondence should be addressed to Minshi Chen; [email protected]

Received 5 March 2019; Accepted 15 May 2019; Published 16 June 2019

Academic Editor: Radoslaw Zimroz

Copyright © 2019 Hongfei Guo et al. +is is an open access article distributed under the Creative Commons Attribution License,which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

In view of the common and difficult to solve vehicle vibration problem, taking a large truck manufacturing enterprise inChina as an example, an improved model for solving truck vibration problem is established by using the G8D method, andthe unbalanced excitation force of the wheel system is analysed. +e coupling of the excitation frequency and the naturalfrequency of the system leads to the resonance phenomenon, as well as the inadequate damping function of the system, isthe fundamental cause of the vibration problem. After verifying and implementing permanent correction measures at thesame time at the three levels of components, devices, and the entire vehicle, the acceleration of the seat guide rails for thevibration performance of the truck reduces from the original state 1.04 m/s2 to 0.6 m/s2, a decrease of 42.3%, which reachesthe best level of mainstream cars in the country and is close to the optimal level of 0.5 m/s2 among the same kinds of cars inGermany. +erefore, the improved model can improve the sustainability of product manufacturing, provide industryguidance for solving the quality problem of truck vibration, and provide a sustainable guarantee for social publictransport safety.

1. Introduction

+e vibration of the truck mainly refers to the vibrationproduced by the cab when the truck is running on thesmooth road surface, which is the most common and dif-ficult quality problem in truck vibration [1]. +is vibrationwill not only make the truck occupants feel uncomfortablebut also affect their normal operation and even increase therisk of causing traffic accidents [2]. At the same time, thevibration problem is the quality problemwhich the customerrepeatedly requests to correct, directly affects the customerto the product cognition, and negatively blocks the passageof the product manufacture sustainable development [3].But, in the actual work, most of the researchers only analyzea certain vibration phenomenon and then propose a singlesolution, which is lack of systematic solutions.

In this paper, G8D (also known as Global 8 Disciplines,TOPS 8D) is used to analyze the vibration problem sys-tematically [4]. First, temporary measures are taken to solvethe problem temporarily, and then, permanent correctivemeasures are taken to solve the problem thoroughly in-volving the coordination of various departments in order tosolve this problem thoroughly in system and regulation. Animproved model of G8D is put forward to solve the problemof truck vibration in the system, and the permanent cor-rection measures are verified and put into practice inthree levels of components, devices, and whole vehicles.+e quality problem of truck vibration has been improved,which has reached the mainstream level in China and isclose to the level of the same kind of car in Germany.+erefore, the application of the improvedmodel of the G8Dsystem to solve the problem of truck vibration has stronger

HindawiShock and VibrationVolume 2019, Article ID 1416340, 11 pageshttps://doi.org/10.1155/2019/1416340

mailto:[email protected]://orcid.org/0000-0001-5819-2138https://orcid.org/0000-0002-9360-4908https://creativecommons.org/licenses/by/4.0/https://doi.org/10.1155/2019/1416340

applicability and sustainability to the quality improvementof truck manufacturing industry [5].

2. Theory and Methodology

2.1. G8D. +e G8D method is one of the most widely usedproblem-solving tools related to the prevention of repeatednonconformities in the manufacturing process and is oftenused for complaint management in the automotive industry.Ford Motor Company pioneered 8D problem solving inmid-1980 [6] for use by its suppliers to improve problemsolving. +e G8D has been widely used in the automotiveindustry service or product problem solving [7], includingsupplier quality issues, manufacturing process deviation,defect [8], maintenance, customer complaints, returns, andother issues. +e main area of current research is in in-dustrial process quality improvement [9], which facilitatesincreased productivity and timely handling of customercomplaints [10].

For the study of vehicle vibration problem, most of theresearchers only analyze a certain vibration phenomenonand then propose a single solution, which lacks systematicsolutions. And, the situation of recent research is shown inTable 1.

+is paper introduces a set of improved models of G8Din solving truck vibration problem, provides a generalprocess to effectively identify and solve the problem, andprovides a method to identify the root cause and implementappropriate corrective action. +is approach identifies thechanging needs of the system, emphasizes teamwork, in-creases management understanding of the problem itselfand the problem solution, encourages direct and openproblem resolution, and prevents the recurrence of the sameproblem and other similar problems. Compared with thetraditional researchmethods, it is more universal to solve thevehicle vibration problem systematically.

2.2. Related �eories on the Fundamental Causes of VehicleVibration

2.2.1. Exciting Force. +e exciting force comes from severalaspects: the imbalance of the wheel system, the imbalance ofthe drive shaft system, and the unsmoothness of the roadsurface.

2.2.2. Ability of Vibration Isolation and Absorption. +esystem has a front axle shock absorber and cab front and rearsuspension shock absorber [15], and the engine suspensionforms the vibration isolator of the vehicle system andprovides the system with the ability to reduce vibration.

2.2.3. Resonance Phenomenon. +e frame, the suspensionspring of the front axle, and the shock absorber of the frontaxle constitute a “mass-spring-damping” system [16], andthe powertrain with its front and rear suspensions forms the“mass-spring-damping” vibration system [17]. A mass-spring-damping vibration system [18] is formed betweenthe cab and the following suspension springs and dampers.

Each of these systems has its own resonant frequency. +efrequencies of these systems should not be the same or closeenough to form resonant coupling; at the same time, theseresonance frequencies should be as far away as possible fromthe excitation frequencies of the system, such as the exci-tation frequency of the tire, if the resonance of the system isinevitable. If the exciting frequency of the tire coincides withthe resonance frequency of a certain system, the vibrationabsorber of the system should reduce the vibration ampli-tude of the system as much as possible.

3. Improvement Process of Truck Vibration

In view of the vibration problem existing in truckmanufacturing, the G8D is used to establish an improvedmodel for solving the truck vibration problem. In the ap-plication of the G8D, step D1 “establishing a team” and stepD8 “summing up and commending” are omitted because itsimplementation can be carried out by the enterprise man-agement department. +erefore, the improved model ofvibration problem is elaborated mainly from D2 to D7, andthe quality improvement tools in G8D are used to solve theproblem of vibration. +e specific model is shown inFigure 1.

3.1. Reaction to the Problem (D0). To prepare the applicationof G8D, it is necessary to analyze the characteristics andobjectives of the problem. Taking a large truck manufacturingenterprise in China as an example, there may be someproblems of installation technology or improvement of somemanufacturing methods in the production process of local-ization of technology and drawings in Germany.

Truck vibration has the following characteristics: for thesame type of truck, some vehicles have vibration problems,but the rest of the vehicles do not have this problem, whichshows that there is no problem in the design of vehicles.+erefore, it can be considered that the vibration of thevehicle is caused by themanufacture and installation of someparts, and this kind of problem is very suitable to be solvedby G8D.

+e G8D requires defining the objectives to be solved byusing this method: one is to solve the vibration problem of thetruck, the other is to confirm whether the vibration of the cabexists, and the third is whether the existence of the problem isserious enough to affect the delivery of the vehicle.

3.2. Description of the Problem (D2). +e first key step tosolve the truck vibration problem is to describe the truckvibration problem accurately, including the accurate de-scription of the characteristics and manifestations of thevibration. Based on the facts, the paper states problems fromthe following aspects as in Table 2.

3.2.1. 5Whys. +rough observation and test, it is found thatthe acceleration of the seat guide rail near the vehicle speed(65 km/h) is the largest and the vibration is very serious inthe vertical direction of 2.10m/s2 and in the longitudinal

2 Shock and Vibration

direction of 2.02m/s2 calculated from formula (1). Fromformula (2), the vibration frequency is near 5.55Hz. +iskind of vibration is produced only on the smooth roadsurface, the speed maintains in the vibration speed, and the

vibration is more serious, which causes the passenger dis-comfort [19]:

ajb � n

1 Fia × VTFiajb , (1)

where ajb is the acceleration response of point j direction b(m/s2); Fia is the load force of point i direction a (N); VTFiajais the vibration transfer function from point i direction a topoint j direction b (m/s2/N). +e formula means the vi-bration response is the load force of each driver point andeach direction produces the VTF from the driver point to theresponse point. If the vibration acceleration of responsepoint is to be reduced, the following three aspects need to becontrolled [20]:

f � num ×n

60, (2)

where num is the order and n is the speed. Formula (2)indicates that each order frequency of the vibration signal isclosely related to the wheel speed.

Table 1: Summary of research on vehicle vibration.

Researchers Research object Cause of the problem Research methodsSim et al. [11] Brake flutter deceleration suspension Uneven contact between brake disc and gasket Vibration path analysis

Yang and Zuo[12] Tyre self-excited vibration

+e difference between the component speed ofa vehicle’s speed and the lateral direction of the

tire

Numerical simulationmethod

Liu et al. [13] Whole vehicle vibration Insufficient stiffness of lower arm drive shaftand bushing of suspension Substructure power flow

Hao et al. [14] Vehicle longitudinal low-frequencyvibrationInsufficient tire slip and half shaft torsional

stiffness 3-dof model

D0: response to the problem Analysis on manufacture and installation of truck parts

D1: establishment of the panelEstablish a study group on truck vibration

D2: description of the problem Describe the characteristics and forms of vibration

D3: development of immediate corrective actionDevelop urgent measures to address the vibration

problem

D4: analysis and identification of root causesAnalysis and confirmation of unbalanced exciting force

and coupling resonance

D5: development of permanent corrective actionReducing the amplitude of exciting force and increasing

system damping

D6: implementation of permanent corrective action

Is that theroot cause?

Standard test

Evaluation ofthe feasibility of corrective

measures

Validity testVerification of permanent correction measures from

three levels

D7: prevention of problem recurrenceThe key problems and suggestions to solve vibration

are put forward

D8: summary and recognitionSummary of the systematic method and recognition of

relevant personnel

Invalid

Valid

No

Valid

Invalid

Valid

Yes

Invalid

Problem statement5Whys

Yes and No worksheet Truth factor assessment

Decision worksheet

Problem prevention list

5Whys

Figure 1: Improved model of G8D in systematically solving the problem of truck vibration.

Table 2: Problem statement method.

No. Description of the problem

① Specific components of vibration(e.g., steering wheel, seat, cab)

② +e manifestation of vibration(e.g., torsional vibration, reciprocating vibration)

③ Direction of vibration (longitudinal,transverse, vertical, etc.)④ Speed at which vibration occurs (engine speed)

⑤ Road conditions during vibration(smooth/rough road surface, uphill, etc.)⑥ External environment (e.g., wind speed, temperature)

⑦ Load condition during vibration(no load, heavy load, traction, etc.)⑧ Changes in vehicle design and manufacture

Shock and Vibration 3

In order to find out the corresponding problems anddefine the root causes of vibration, the five-question method(“repeatedly ask why”) is adopted in this paper as in Figure 2.

3.2.2. “Yes and No” Worksheet. +e Yes and No worksheetsdescribe the extent of the problem as in Table 3, and only thecorrect information is included in this table, which is part ofthe observation phase as part of the problem resolutionprocess. +e information in the Yes section of the worksheetdetermines the root of the problem and the No section helpsnarrow the scope of the problem.

3.2.3. Truth Factor Assessment. (1) Manifestation of VehicleVibration. +e vehicle vibration is represented by the ver-tical, transverse, and longitudinal vibration of the steeringwheel [21]; vibration of the gear; vibration of the floor in thevertical direction; vibration of the seat in the vertical andforward and backward directions; and vibration of the leftand right rear mirrors in the cab.

(2) Evaluation Method of Vehicle Vibration. +e vi-bration of the vehicle is evaluated by measuring the vibrationacceleration of the seat guide rail in three directions with thehelp of data acquisition equipment. In the absence of anytesting means, it is also possible to evaluate the vibration of avehicle with the subjective evaluation method, as well as theend-user, and judge whether the vibration exists and itsseverity and acceptability from the point of view of a productconsumer to determine that it can be put on the market.

(3) �e True Cause Evaluation of Vehicle Vibration

(1) Quality problems of core components: the pro-cessing of some rotating parts (such as transmissionshaft, semishaft, rim, hub, tyre, and brake hub) doesnot meet the technical requirements, and deviationresults in mass eccentricity when assembly does notmeet the technical requirements. +ese eccentricmasses produce periodic exciting forces when thevehicle is running.

(2) Tyre exciting force: the periodic exciting forceproduced by the unbalanced wheels in the running ofa vehicle is transmitted to the frame through the leafspring and then to the cab.

(3) Tire vibration mode: there are two modes of tirevibration, jumping mode and swinging mode. +efirst is the run-out mode, in which the vibrationphase of the left and right tires is the same, that is,when the left tire jumps to the top, the right tirejumps to the top, and when the left tire jumps to thebottom, the tire on the right jumps to the top, and thetire on the left jumps to the bottom. +e tire on theright is also bouncing to the bottom. +e second isthe swing mode, in which the vibration phase of theleft and right tires is just the opposite, that is, whenthe left tire jumps to the top, the right tire jumps tothe bottom, and when the left tire jumps to thebottom, and the tire on the right, however, leaps tothe top.

(4) Cab and seat vibration: the vibration problem dis-satisfied with by the end-user is often the cab and seatvibration [22]. And, the overwhelming majority ofthe unbearable vibration of the cab and seat is thatthe body is in the jumping mode [23]. +e reason forthis vibration is that the exciting force produced bythe static and dynamic imbalances of the tire is in therun-out mode, the front tire is in the run-out mode,or the rear tire is in the run-out mode. Another is thefront and rear tires are in the bounce mode. +efrequency of the jumping mode may be consistentwith the mass of the frame and the rear axle platespring and the natural frequency of the spring sys-tem, or with the mass of the frame and the front axleplate spring and the natural frequency of the springsystem, which puts the frame into a resonant state atthe same frequency as the radial force on the tire.+eresonance state of the frame is transferred to the cabthrough the cab suspension. If the stiffness of the cabsuspension is not matched properly, the excitationfrequency of the wheel system coincides with themass of the cab and the body suspension and thenatural frequency of the spring system and then,resonance occurs again.

3.3. Development of Immediate Corrective Action (D3). Inthe case of vibration problems, it is necessary to takeemergency response measures and choose ImmediateCorrective Action (ICA), to solve the vibration problemsprovisionally, but the premise of the proposed measures isthat the existing design, manufacturing, and installationmethods and processes cannot be changed and no cost canbe increased. +us, the vehicles will be put into use so thatthe customers who purchase these vehicles will not beaffected by the vibration of the vehicles and damage thereputation of the quality of the vehicles. +e criteria forselecting emergency response measures are shown inTable 4.

Based on the above criteria, immediate corrective actionsadopted include, but are not limited to, are as follows:

(1) +e front right wheel and the rear right wheel tire arerotated 180 degrees before reinstallation

(2) Under the condition of keeping (1), the rear axle tiresare cross-suspensioned on the left and right sides

(3) Use a better cab suspension [24](4) Use a better front axle damper [25](5) Select tires, brake drums, and wheels with small

dynamic unbalances

3.4. Analysis and Identification of Root Causes (D4)

3.4.1. Describing Root Causes and Missing Points. +emissing point is a point that is very close to the root cause;that is, it omits to analye what should have been the problem.No missing points were found in this particular vibrationproblem of the enterprise.


Based on the results of the problemmethod stated in D2,the “Yes and No” worksheet, the “5Whys,” and the truthfactor assessment, the enterprise can tentatively determinethat the cause of the truck vibration is the unbalanced ex-citation force of the vehicle’s wheel system, the coupling ofthe excitation frequency and the natural frequency of the

system that leads to the resonance phenomenon, and at thesame time, the insufficient damping function of the system,as described in detail as follows:

(1) Wheel systems (including tires, hubs, and rims)have significant manufacturing defects [26], suchas nonroundness of wheels and rims. +e un-evenness of the inner and outer edges of the rim(that is, the inner and outer edges are not in thesame plane) results in the imbalance of the tiresystem. In the operation of the vehicle, these un-balanced forces become the excitation force of thesystem vibration.

(2) +e dynamic imbalance of the drive shaft system isone of the factors that cause the vibration of thesystem.

1. Why is the cab vibrating?Because of the vibration of the frame, the vibration is amplified by the body mount.

2. Why does the body mount magnify the vibration? The coupling of modal and excited frequencies of the cab results in resonance due to improper stiffness matching of the suspension.

3. Why does the body mount match improperly?

Poor control over suppliers, lack of quality checks, and inconsistent vehicle mount condition.

4. Why is the frame vibrating at 65~70km/h?

Because of the large unbalanced excitation force of the wheel system, the excitation frequency is coupled with the rear bias frequency of the whole vehicle at this speed.

5. Why is the unbalanced excitation force of the wheel system so large?

Due to lack of quality control and inspection, and roundness and flatness of rims, wheels and brake hubsdo not meet the technical requirements.

6. Why has not the cab vibration been damped off?

Because the front and rear axle leaf springs, dampers and cab suspension dampers do not work very well.

7. Why damping shock absorbers don’t work well?

Because vibration absorbers are accepted without quality inspection, some dampers do not work.

Figure 2: “5Whys” method to determine the root cause.

Table 3: “Yes and No” worksheet.

Problem-solving worksheet: does the truck have a vibration problem?(1) Problem statement.+e truck has longitudinal and vertical vibration in the cab at a speed of 65 km/h and 70 km/h in no-load condition(2) Problemdescription Yes No

Access toinformation

Problem

1 +e longitudinal and vertical vibration of a cab ofvehicle Steering wheel without vibration Measurement result

2 +e rear of the frame bounces in a verticaldirection Shift lever without vibration Measurement result

3 +e middle rear axle flutters along the verticaldirection Measurement result

Occurrenceplace

1 Cab Test data2 Frame of a vehicle Test data3 Middle rear axle Test data

Occurrence time 1 New car2 Vibration at speed 65∼70 km/h Other speed does not vibrateSeverity 1 In a severe state of discomforts Other speed does not exist same situation Live video recording

Table 4: Criteria for selecting emergency response measures.

ICA Specific description

(1) Reduce exciting force Reduce the source ofvehicle vibration

(2) Enhance shock absorber Increase damping toattenuate vibration(3) Avoid the resonancefrequency of the system

Avoid exciting frequencyas much as possible


(3) Because the frequency of exciting force produced bythe wheel train in the 65∼70 km/h is about 5.5Hz,this resonance frequency obviously coincides withone of the frequencies of the above three vibrationsystems and produces resonance. +e connection tothe cab through the system causes the cab to reso-nate. Another reason is that the natural frequency ofthe cab itself is consistent with the excitation fre-quency, resulting in resonance.

(4) Shock absorbers for vehicles due to manufacturingquality inconsistencies [27] cause the component failto meet the technical requirements of providingsufficient damping during resonance [28], therebyreducing the resonance amplitude of the system. +edamping force of the shock absorber of the front axleis not large enough [29]; when the front axle resonates,the amplitude of the resonance cannot be attenuatedto the design level; the shock absorbers of the engineand the cab are unable to provide sufficient dampingbecause of inconsistent manufacturing quality.

3.4.2. Confirming Description. As shown in Figure 3, thevertical acceleration of the middle rear axle near 65 km/h islarge [30], up to 4.76m/s2; magnified to 5.21m/s2 from therear axle spring to the frame (at balance suspension). Fromthe frame to the cab, the cab front suspension amplifies thevibration (1.78m/s2 to 3.05m/s2) and the cab rear suspen-sion attenuates the vibration (3.11m/s2 to 2.05m/s2).

+e cause of vibration can be determined as follows:when the vehicle speed is 65 km/h, the unbalanced excitingforce produced by the rotating parts of themiddle rear axle isrelatively large [31]. When passing through the rear axle leafspring, it is coupled with the rear bias frequency of the wholevehicle, so the acceleration on the frame is amplified, [32]and the acceleration transferred from the frame to the cabthrough the front suspension of the cab is magnified. It iscoupled with a certain order of the rigid body mode of thecab when it pass through suspension in the cab, and theacceleration transmitted from the frame to the cab throughthe front suspension of the cab is magnified, causing thetruck to vibrate.

(1) Replace Cab Suspension. +e cab of the vehicle wassuspended with an air spring and is now replaced with ahelical spring damper. +e acceleration on both sides of cabsuspension near 65 km/h with different brands of shockabsorbers is listed as Table 5.

Plan A: the front suspension is replaced by the brandone spiral spring damper, and the rear suspension isreplaced by the brand two spiral spring damper.Plan B: the front and rear suspensions are brand onespiral spring shock absorber.

After replacing the cab suspension, the vibration of thecab front suspension is no longer amplified, the verticalacceleration of the cab is reduced from 2.10m/s2 to 0.68m/s2, and the longitudinal acceleration of the cab is reducedfrom 2.02m/s2 to 0.56m/s2. +e cab vibration is obviously

improved. +ere is no significant difference in the isolationrate between the two types of spiral spring shock absorbers.

(2) Replace the Dynamic Balance Brake Hub and DynamicBalance Tire. +e acceleration comparison before and afterdynamic balancing is shown in Table 6.

After dynamic balancing, the vibration acceleration ofthe main seat guide rail decreased by 30.36% in longitudinaldirection and 45.59% in vertical direction. +e vibrationacceleration at the left wheel of the rear axle is still large andbecomes the main excitation, which may be caused by thepoor dynamic balance of the left rear axle tire and brake hubor the assembly error.

+e manufacturing inconsistency of the wheel hub, theuneven flatness of the inner and outer edges of the wheelrim, and the uneven roundness of the rim can also beconfirmed by observation. Overall, the test results show thatthe brake hub and tire with dynamic balance have a greatattenuation effect on the vibration.

3.5. Selection and Validation of Permanent Corrective Actionsfor Root Causes and Missing Points (D5). In order to de-termine the permanent corrective action (PCA), the prin-ciple is to reduce the amplitude of the exciting force, separatethe modes of the system [14], and increase the damping forceof the system [33]. +ere are six permanent measures listedin Table 7. If you have more than one vendor for these 6components, you can use the decision table in Table 8 toselect a good vendor.

According to the data in Table 8, the standard scoreexpected by supplier A is 52 and the standard score expectedby supplier B is 48 (the full score is 60). Meanwhile, supplierB cannot meet the standard of “not increasing the cost of theproduct.” In the light of the above decisions, vendor Ashould be selected.

3.6. Implementation and Validation of Permanent CorrectiveAction (D6)

(1) Dynamic balance of transmission shaft: put forward,check, and carry out the technical requirementsabout the size and dynamic balance of transmissionshaft and have corresponding quality inspectionmechanism

(2) Dynamic balance of wheel hub: put forward, check,and carry out the technical requirements ofroundness dimension and dynamic balance of wheelhub and have corresponding quality inspectionmechanism

(3) Dynamic balance of wheel rim: propose, check, andimplement the technical requirements of rim size,roundness, and dynamic balance and have thecorresponding quality inspection mechanism

(4) Dynamic balance of tire assembly: put forward,check, and implement the technical requirements ofstatic and dynamic balance of transfer tire assemblyand provide technical assistance to suppliers to


Am

plitu

de (m

/s2 ) 3.10

0.00

Am

plitu

de (m

/s2 ) 3.20

0.00

Am

plitu

de (m

/s2 ) 5.30

0.00

Am

plitu

de (m

/s2 ) 4.80

0.00

Am

plitu

de

1.00

0.00

Am

plitu

de

1.00

0.00

Am

plitu

de

1.00

0.00

Am

plitu

de

1.00

0.00

F Spectrum Rear suspension body side of cab: +ZSpectrum Front suspension body side of cab: +ZF

F Spectrum Rear suspension frame side of cab: +ZSpectrum Front suspension frame side of cab: +ZF

F Spectrum Right side of balanced suspension: +Z

F Spectrum Right side of middle axle: +ZF Spectrum Right side of rear axle: +ZF Spectrum Left side of middle axle: +ZF Spectrum Left side of rear axle: +Z

Spectrum Left side of balanced suspension: +ZF

3.05

2.05

1.78

5.53

Hz0.00 15.00

Hz0.00 15.00

Hz0.00 15.00

Hz0.00 15.00

5.53

3.11

5.15

4.763.193.324.31

5.77

5.21

5.77

Figure 3: Transmission of vibration acceleration.

Table 5: Acceleration (m/s2) on both sides of cab suspension near 65 km/h.

Cab shockabsorber

Frontsuspensionbody side

Frontsuspensionframe side

Front suspensionvibration isolation rate

Rearsuspensionbody side

Rearsuspensionframe side

Rear suspensionvibration isolation rate

Original airspring 3.05 1.78 −4.68 dB 2.05 3.11 3.62 dB

Ex-brand 1,post-brand 2 1.39 2.37 4.63 dB 1.29 2.01 3.85 dB

Both are brandone 1.96 3.30 4.53 dB 1.61 2.55 3.99 dB

Notes: Vibration isolation rate� 20 log (active side vibration amplitude/passive side vibration amplitude).

Table 6: Acceleration comparison before and after dynamic balancing (m/s2).

Measuring point position Before dynamic balancing After dynamic balancing Reduced percentageMain seat guide (longitudinal) 0.56 0.39 30.36%Main seat guide (vertical) 0.68 0.37 45.59%On the left wheel of the middle axle (vertical) 4.31 1.41 67.29%On the right wheel of the middle axle (vertical) 4.76 1.85 61.13%At the left wheel of the rear axle (vertical) 3.31 3.21 3.02%At the right wheel of the rear axle (vertical) 3.19 2.15 32.60%


purchase static and dynamic balance equipment oftire

(5) Provide the supplier with hardness and technicalrequirements for reinforced powertrain suspensionrubber, and urge and assist them to achieve thesetechnical requirements and consistency of productcharacteristics; it can be listed in Table 9

(i) +e technical requirements for the dampingcharacteristics of the hysteresis curve of the frontaxle damper are presented to the supplier

(ii) +e technical requirements for the dampingcharacteristics of the hysteresis curves of the

front and rear suspension dampers of the cab areproposed to the supplier

+e quality of these components must meet the qualityand technical requirements of the enterprise, and there is asystematic mechanism to implement and verify the imple-mentation of the quality and technical requirements of thesecomponents.

+ere are three levels of validation for these permanentcorrective measures:

(1) Component level: correct the dynamic balance of therotating parts of the vehicle: drive shaft, wheel hub,rim, and tire assembly [34], ensure the supplier’s

Table 7: Decision worksheet on permanent corrective measures.

Decision worksheet 1Final result: eliminate or reduce vibration in operation of this type of vehicle to the extent acceptable to the customerCriteria that must be met(a) Do not change existing design(b) Do not change the manufacturing process(c) No increase in product costExpected standard Importance (1–10, 1: minimum, 10: maximum)(1) Deviation quality and consistency of transmissionshaft 8

(2) Technical requirements for hub: roundness andflatness and consistency 9

(3) Rims meet technical requirements: roundness andconsistency 9

(4) Dynamic balance and consistency of tire assembly 9(5) Damping force of front axle shock absorber meetstechnical requirements and consistency 8

(6) Cab-suspensioning shock absorber meetstechnical requirements and consistency 9

Table 8: Vendor decision worksheet.

Decision worksheet 2Vendor A Vendor B

Criteria that must be met Yes/no Criteria that must be met Yes/no(a) Do not change existing design Yes (a) Do not change existing design Yes(b) Do not change the manufacturingprocess Yes (b) Do not change the manufacturing process Yes

(c) No increase in product cost Yes (c) No increase in product cost No

Expected standard Good or bad(1–10) Score Expected standardGood or bad

(1–10) Score

(1) Deviation quality and consistency oftransmission shaft Good 8

(1) Deviation quality and consistency oftransmission shaft Good 9

(2) Technical requirements for hub:roundness and flatness and consistency Good 9

(2) Technical requirements for hub:roundness and flatness and consistency Good 8

(3) Rims meet technical requirements:roundness and consistency Good 8

(3) Rims meet technical requirements:roundness and consistency Good 8

(4) Dynamic balance and consistency oftire assembly Good 9

(4) Dynamic balance and consistency oftire assembly Good 7

(5) Damping force of front axle shockabsorber meets technical requirementsand consistency

Good 9(5) Damping force of front axle shockabsorber meets technical requirements

and consistencyGood 8

(6) Cab-suspensioning shock absorbermeets technical requirements andconsistency

Good 9(6) Cab-suspensioning shock absorbermeets technical requirements and

consistencyGood 8


parts meet the technical standards, and check thedynamic balance

(2) Device level: correct the cab damper and front axledamper, ensure that the parts of the supplier meetthe technical standards, and detect the stiffness anddamping of the damper [35]

(3) Whole car level: load the car with the modified partsand carry out the road test to see the improvementeffect of the vibration performance of the whole car[20]

3.7. Prevent ProblemRecurrence (D7). +e “5Whys” methodis still used here to determine the root cause of the problemand the permanent measures that should be taken to preventthe recurrence of the problem. According to the theory ofG8D, it can be used to find out the problems about system,operation, process, or policy. Systemic problems arise fromfull references to previous organizations, technical processes,policies, and practices. +ese past processes, policies, andpractices are often not applicable to the current situation andare not traceable.

+e method proposed in this paper is very effective insolving the vibration problem systematically and makes thevibration problem be systematically tracked and controlled.According to the above analysis and the actual situation, thispaper puts forward some suggestions on the existing systemof the enterprise in order to prevent the recurrence of theproblem.

(1) +e quality inspection mechanism of enterprisesneeds to be perfected. +is is responsible for

formulating product quality inspection standards,checking the quality of parts provided by suppliers,spot checking the qualified rate of products; thesupplier shall provide quality product certificationaccording to the requirements of the enterprise; if itdoes not meet the requirements, it will not accept thesupply.

(2) +e supplier quality evaluation system is yet to beestablished. +e related personnel is responsible forsupplier quality review and supplier classificationmanagement. In the case of unqualified products,enterprises need to have accurate technical means, toprovide suppliers with accurate technical evidence ofnonconforming products and specific rectificationprograms for suppliers to rectify according to spe-cific technical objectives.

(3) Technical support for supplier quality improvementis to be provided. +e relevant departments are re-sponsible for technical guidance and help suppliersto improve quality, suppliers, and enterprises in thequality of a virtuous circle; that is, enterprises dotheir best to promote suppliers to improve quality,reward, and punishment system for suppliers andlaunch mechanisms. +e quality of suppliers isgradually improved due to technical feedback andassistance.

(4) Supplier product quality feedback system is to beestablished. Let the supplier define the technical andquality requirements of the enterprise and form aclosed loop between the quality of the product of thesupplier and the requirements of the enterprise. +e

Table 9: Problem prevention worksheet.

Problem prevention worksheetProgram objective: to prevent vehicle vibration in terms of the manufacturing quality of components

Key step Nature Possible obstacles/causes of problemsP S P × S

(1) Deviation quality and consistency of transmissionshaft(2) Technical requirements for hub: roundness andflatness and consistency(3) Rims meet technical requirements: roundness andconsistency(4) Dynamic balance andconsistency of tire assembly(5) Damping force of front axleshock absorber meets technical requirements andconsistency(6) Cab-suspensioning shockabsorber meets technical requirements andconsistencyUse your experience to identifyyour plans and steps

+ese steps are complex, havetight deadlines, are new, andhave an impact on other steps

Determine whichsteps

require yourattention

and resources most

Identify possible obstacles to completing these keysteps. (people, methods, materials, machines,measurements, and environmental problems)

Notes: questions such as the nature of the form need to be filled out later.


enterprise forms the complete system and themechanism, causes the supplier and the enterprisemain engine factory’s technical information to forma closed loop, strengthens the system informationexchange between each other, and forms the tech-nical accumulation for the past problem solving toprevent similar problems from happening in otherlocations or on other models.

4. Discussion and Conclusions

By applying the G8D, an improved model for solving thetruck vibration problem is established. At the same time,according to the results of the statement problem method,the Yes and No worksheet, the 5Whys method, and the truthfactor assessment, the reason for determining the truckvibration is the unbalanced excitation force of the vehiclewheel system, the resonance phenomenon caused by thecoupling of the excitation frequency with the natural fre-quency of the system, and the insufficient damping functionof the system. +erefore, the corrective measures forchanging the wheel hub of cab suspension and dynamicbalance brake hub and dynamic balance tire are put forward.+en, the permanent correction measures are verified fromthree levels of components, devices, and whole vehicles byusing “decision worksheet” and “problem preventionworksheet” to ensure the accuracy and feasibility of themodel and make recommendations for the existing systemof the enterprise to prevent recurrence of problems in thefuture.

After the implementation of the abovementioned com-plete and improved model, the acceleration of the seat rail ofthe truck’s vibration performance has been reduced from1.04m/s2 to 0.6m/s2, 42.3% lower than that of the original car,reaching the level of 0.6m/s2 of the major domestic modelsand close to the level of 0.5m/s2 of its German counterpart,which prevents users from returning their cars. For thecompany to reduce certain economic losses, the sustainabilityof product manufacturing and enterprise economic benefitshave to be improved [36]. +e practical implementation ofG8D can solve many technical problems, but the wholeenterprise needs to pay attention to G8D training, whichenables G8D become a sustainable solution to the problem ofenterprises. +is is of great significance for solving the truckvibration problem and even the quality problem of the wholeautomobile manufacturing industry, which is meaningful forthe sustainable construction of the industry. Most impor-tantly, it contributes to the sustainable guarantee of the publictraffic safety of the society [37].

Data Availability

+e numerical data used to support the findings of this studyare included within the article.

Conflicts of Interest

+e authors declare that there are no conflicts of interestregarding the publication of this paper.

Acknowledgments

+is research was funded by the Enterprise ManagementInnovation Project of the National Defense Science andTechnology Industry (grant no. 13315502), FundamentalResearch Funds for the Central Universities (grant no.21618412), Inner Mongolia Autonomous Region Scienceand Technology Innovation Guide Award Fund Project(grant no. 103-413193), Scientific Research Project of HenanColleges and Universities in 2019, based on the research onmilitary science and technology innovation mechanism ofcolleges and universities from the perspective of civil-military integration (grant no. 19A630037), Fund of Re-search on Enterprise Management Innovation Mode System(grant no. 44860070), and Fund of Research on the En-terprise Management Mode and Countermeasures Based onthe Production, Study and Research (grant no. 44860071).

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