Table of Content

10 August 2014, Volume 25 Issue 15

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Influences of Design Parameters on Meshing Stiffness of Herringbone Gear with High Contact Ratio

He Zhaoxia, Liu Geng, Chang Lehao

2014, 25(15):  1989-1993. 

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In order to help to design herringbone gear system with high contact ratio, a knowledg discovery method was proposed, which combined fuzzy mathmatic with rough sets theory (RST). At first, a fuzzy clustering method was applied on the simulation results and helped to acquire the classification of the tooth meshing stiffness. Then, the design decision rules were deduced by discretization of simulation parameters, the reduction of attributes and values which were based on the RST. And these rules show the relationship among the meshing stiffness and design factors. At last, the illustration of three new samples demonstrates the validity of this new method in application of knowledge discovery of simulation data.

Analysis of Friction Coefficient in Sliding Model of Double Rough Surfaces

Lai Lianfeng, Gao Chenghui, Huang Jianmeng

2014, 25(15):  1994-1998. 

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A three-dimensional W-M fractal sliding model of double rough surfaces was established, and considering the factors which contained interface shear strength, sliding speed and normal load influenced the whole sliding process. The friction coefficient of sliding processes was analysed using the finite element analysis taking into account adhesion factors in the process of contact. The numerical results show that the average coefficient of friction is as 0.28 under the boundary-lubricated, the average coefficient of friction is as 0.713 under the unlubricated interfaces, the average coefficient of friction is as 0.73 under the max interfacial shear strength. With the decrease of the interface shear strength, the increase of normal load and the increase of sliding velocity, the average coefficient of friction is decreased. Compared with experimental results or related documents, it is concluded that the results are of rationality, these results also provide theoretical reference for the tribological design and preparation of friction materials.

Kinematic Characteristic State Models for Basic Units of Compound Gear Train

Ma Yali, Zhang Yongzhen

2014, 25(15):  1999-2003. 

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This paper presented a new modeling approach for unit kinematic characteristic state on the motion analysis of compound gear trains. Gear basic units were defined according to studying the composite rules and decomposing the constitution of compound gear trains. Based on prototypes of gear basic units, gear mechanism diagrams of basic units were set up using topological characteristics of mechanism. Kinematic vector was built to describe the type and direction characteristics of motion. The kinematic characteristic model was established by using state equation. All of them provides a solid theoretical basis for kinematic conceptual design of gear trains.

Design and Analyses of Ultrasonic Spinning Amplitude Transformer

Bu Jianan, Zhang Xu, Li Xinhe

2014, 25(15):  2004-2008. 

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In an ultrasonic spinning system, amplitude transformer was made from luffing rod and rotary wheel, the resonance vibration modes were: luffing rod longitudinal vibration, disc bending vibration. Since it was very complex to compute for this type of oscillator, it was difficult to obtain accurate size directly. In order to achieve design requirements of the frequency and vibration mode, it was necessary to constantly change the size during design process. This paper gave a lot of numerical simulation analyses for the amplitude transformer by means of the MSC. Marc finite element analysis software, the influences of each size of the spinning wheel on the resonance frequency of amplitude transformer were studied, the influence law of each size of the spinning wheel on the resonance frequency of amplitude transformer was obtained. An amplitude transformer which can meet the requirements is designed, and the desired effect of vibration was obtained in the tests.

Vibro-acoustic Coupling Analysis of Combustion Chamber

Ai Yanting, Wang Changxu, Guo Xiaoling

2014, 25(15):  2008-2012. 

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The vibro-acoustic coupling affected combustion stability of the chamber, augmented chamber structure fatigue damage. Therefore, the study of vibro-acoustic coupling characteristics of a combustion chamber structure was essential for its design to increase combustion stability and resist fatigue damage. A three dimensional structural-acoustic model was built by using finite element software to study the vibro-acoustic coupling characteristics of a closed structure combustor, and then the natural frequencies and modal shapes were worked out. The combustor acoustic-structure transfer functions were measured in the experiments, while the natural frequencies and modal shapes of the combustor structure within vibro-acoustic coupling were obtained.The results show that the acoustic field, which produces special coupling frequencies, is equivalent to the additional mass added to the structure and reduces the natural frequency of the structure. The experiments verify the correctness of the finite element calculation results, may provide a basis for the design of the combustor liner thin-walled structure.

Study on Sealing Property of O-ring Seal of Automobile Water Pump under Broad Temperature Region

Xie Fang, Feng Changhong, Wang Zhaoxing, Chen Tiejun

2014, 25(15):  2013-2016,2023. 

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Based on the characteristics of rubber O-ring of an automobile engine water pump working in wide temperature domain, a Mooney-Rivlin material model which was relevant to temperature was established to reveal the influences of temperature, fluid pressure and friction coefficient on the contact pressure, equivalent stress and sealing property. The results show that the increase of temperature causes the peak of contact pressure and equivalent stress to decrease exponentially, inducing the sealing reliability reduces. However, the peak of contact pressure of O-ring working in -40~130℃ is considerably larger than that of the fluid pressure, so the O-ring has reliable sealing property. Furthermore, although the increase of fluid pressure induces the increase of the peak of contact pressure, the reliability of sealing will decline for that the increasing speed of contact pressure is lower than that of fluid pressure. Additionally, the friction coefficient has little influence on the reliability of sealing.

CNC Position Servo System with Feedforward Compensation and Differential Feedback

Huang Keyuan, Zhou Taotao, Huang Shoudao, Huang Qing

2014, 25(15):  2017-2023. 

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A feedforward control of CNC position servo system has many advantages as fast dynamic response, high tracking accuracy, practicality and so on, and it is widely used in CNC position servo system. However, it has large overshoot and it contributes little in the step position servo system. Therefore, a new control method was proposed that the differential negative feedback control was introduced on the basis of the servo system feedforward control herein. With adding the differential negative feedback,the feedforward control function was deduced again. So that the differential negative feedback could guarantee the little overshoot and rapid response, and had no bad effection in position tracking performance. The simulation and experimental results verify the feasibility and effectiveness of the analysis and the design. The new control method is applicable to a wide range with its merits of fast response and great practical value.

Effects of Processing Parameters on Cutting Force in Ultrasonic Vibration Milling

Wang Minghai, Li Shiyong, Zheng Yaohui, Li Xiaopeng

2014, 25(15):  2024-2029. 

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In order to improve the machining conditions of milling titanium alloy in traditional ways,the effects of ultrasonic vibration assisted milling in the feeding direction on cutting force were investigated.Net cutting time ratio with different ultrasonic frequencies, amplitudes and cutting speeds were studied quantitatively.Three-dimensional finite element models of milling process  with workpiece ultrasonic vibration were developed. Based on simulation results, these influences of processing parameters on the instantaneous value of cutting force in feeding direction and the average cutting force in three directions were discussed. Research results show that cutting force in ultrasonic vibration milling is much smaller than that of traditional milling's. Moreover,average cutting force is consistent to change trend of net cutting time ratio, but when ultrasonic frequency is over 40kHz or amplitude is over 30μm the friction between tool and workpiece will significantly affect average cutting force.

Study on Dynamic Performance of EFMC System in Hydraulic Excavator

Wang Xiangbing, Tong Shuiguang, Ge Junxu, Zhang Jian

2014, 25(15):  2030-2037. 

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A virtual prototype of EFMC system in hydraulic excavator was constructed by analyzing the control principle of EFMC system based on lastdruck unabhngige durch-fluss verteilung (LUDV) multi-way valve,the accuracy of flow matching was improved by adopting feedback closed-loop control method with real-time detection of oil cylinder speed signals.The dynamic and hydraulic models of EFMC system in hydraulic excavator were constructed respectively, and the co-simulation was conducted based on actual working conditions, the dynamic characteristics and energy-saving characteristics of mining operation process were studied, compared the experimental results with the traditional LUDV load-sensing system, the results indicate that compared with the load-sensing system, the dynamic response characteristics and stability performance of the EFMC system are improved,and the pressure margin is reduced obviously, the energy efficiency is improved, also the dynamic response characteristics of feedback closed-loop control system are improved. Theoretical basis and reference are provided for further research on dynamic characteristics, energy-saving characteristics and stability performance in excavator.

An Iterative Approach to Fixturing Layout Optimization of Robotic Moving Mechanism

Wu Zhuxi, Li Bo, Lu Dong, Lu Yuming

2014, 25(15):  2037-2043. 

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An artificial spraying possessed low efficiency and volatilization of poisonous gas from glue, so an automatic spraying robot for shoe upper was designed. However, the postioning and motion errors of the spraying mouth were caused by the fixturing layout between the radial moving mechanism and the fixing frame. According to the bolt fixturing layout, the finite element method was used to establish the optimal mode of the bolt fixturing layout with the minimum deformation of the outer frame. By defining the minimum deformation of the outer frame as the fitness evaluation of individual, the genetic algorithm was employed to construct an iterative solution technology for the optimal mode of the fixturing layout. The suggested method can determine the optimal positions of the increased bolts to minimize the outer frame deformation during the spraying process. Thus, the spraying uniformity can be guaranteed to improve the shoe durability.

Study and Applications of Tool Path Numerical Algorithm of Complex Helical Surface Manufacture

Kuang Yuchun, Wu Longmei, Dong Zongzheng

2014, 25(15):  2044-2049. 

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In order to improve the machining accuracy of complex helical surface, this paper studied algorithm about the tool path, put forward a numerical algorithm of tool path based on the minimal directed distance. The three-dimensional numerical geometric models of tool and workpiece surface were built, and a numerical calculation model consistent with the real operation was set-up through the coordinate-transformation matrix. To ensure the accuracy and efficiency, the minimal directed distance between tool and workpiece was samplified into a two-dimensional problem by spatial discretization thought. The numerical algorithm of tool path was set-up according to the theory of Archimedean spiral interpolation curve. The results show that it can produce the helical surface meeting precision requirements with NC programming through the method.

Fault Diagnosis Approach for Gears Based on LCD and KNNCH Classification Algorithm

Zeng Ming, Yang Yu, Zheng Jinde, Cheng Junsheng

2014, 25(15):  2049-2054. 

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A gear fault diagnosis approach was proposed based on LCD and KNNCH classification algorithm. Firstly, LCD method was applied to an original gear bearing vibration signals and adaptively decomposed the signals into a series of intrinsic scale components (ISC). Secondly, the energies of the ISCs which contain main information were extracted and regarded as the fault feature vector. Finally, KNNCH classifier accepted the fault feature vector as the inputs, and then the working condition of gear could be identified by the outputs of the classifier. The experimental analysis results show that the proposed approach can effectively extract the fault feature information and accurately classify the working conditions of gear even in the case of small samples. Additionally, the comparative analysis results demonstrate that KNNCH classification algorithm can gain a considerable or better classification rate compared to SVM(support vector machine) algorithm.

Fault Diagnosis of Roller Bearings Based on Characteristic Parameters and Probabilistic Neural Network

Pei Junfeng, Bi Kunlei, Lü Miaorong, He Chao, Shen Kejun

2014, 25(15):  2055-2058. 

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According to the non-stationary characteristics of roller bearing fault vibration signals,a fault diagnosis approach based on on multiple characteristic parameters and probabilistic neural network was proposed. Firstly, original signals were decomposed into a finite number of stationary intrinsic mode functions(IMFs). Energy, kurtosis and skewness feature parameters were extracted from IMFs which contained main fault informations could be served as input parameters of neural networks to identify fault patterns of roller bearings. The experimental results show that the approach can identify working conditions and fault types of roller bearings.

Research on Hysteresis Constitutive Relation in Piezoceramic Crystals

Qin Haichen, Yin Zhouping

2014, 25(15):  2059-2064. 

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Based on the thermodynamics phenomenological theory, a hysteresis constitutive relation of the electric field (E) and polarization (P) was deduced by analyzing the Helmholtz free energy relation of piezoceramic. The experimental hysteresis curve were compared with the academic calculation. The results presented in the hysteresis constitutive relation can describe accurately the hysteretic behavior on a macro-scale. Additionally, the Helmholtz free energy and hysteretic loop were discussed by analyzing experimental data and curves.

Performance Analyses and Experiments of a Piezoelectric Vibration Energy Harvested with Multifrequency Response Capability

Yu Qibing, Zhu Rongrong, Li Chuan,

2014, 25(15):  2064-2069. 

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To improve performance of vibration energy harvesting for piezoelectric cantilever, a vibration energy harvester with multifrequency responses was presented. An auxiliary beam was inserted between the piezoelectric cantilever and vibration base. Two tip masses were installed at the end of the piezoelectric beam and the auxiliary beam respectively. The two beams were connected perpendicularly. The weight of the auxiliary beam mass was designed to be much greater than that of the piezoelectric beam, and the first natural frequency of the piezoelectric beam was chosen between the first two natural frequencies of the auxiliary beam. In this way, the vibration response of the piezoelectric beam is just the sum of multiple frequency bands. An analytical electromechanical model was proposed to describe vibration response and energy harvesting feature of the proposed harvester. A prototype device was developed for testing. The results show that, compared to the conventional cantilevered piezoelectric harvester, the proposed one is capable of harvesting much energy in a broader frequency band.

Parameter Design of FlexRay Dynamic Segment under Time Constraints

Wang Yuefei, Yin Jianli, Zhang Li, Wang Tao

2014, 25(15):  2070-2075. 

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In order to design the parameters of FlexRay network,impacts of several parameters such as the length of the dynamic segment and frame identifier assignment on the network performance of automobile FlexRay were analyzed qualitatively, and calculation methods for the utilization of network bandwidth and the worst case response time of messages were deduced. Under the constraints of message response time, the optimization design model and algorithm for the length of the dynamic segment and frame ID assignment were given, which aimed at the maximum bandwidth utilization and the minimum response time of messages. Experiments made in the simulation platform of CANoe and DaVinci Network Designer show that this design method can improve the dynamic bandwidth utilization effectively and reduce the dynamic message response time.

Dynamics Modeling and Position Control for Shell Transfer Manipulator of a Self-propelled Gun

Guo Yufei, Hou Baolin

2014, 25(15):  2076-2080. 

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Considering the influence of the hull's vibration, the dynamics and position control problem of the shell transfer manipulator for a self-propelled gun were studied herein. Firstly, the dynamics model of the manipulator was established via the Lagrange's equations of the second kind by extracting the hull's vibration as external disturbance. Secondly, based on above dynamics model, a continuous feedback position controller was designed utilizing an implicit Lyapunov function. The controller's gains were differentiable functions of the state variables. Finally, the dynamics equation was solved via Newton's method and Runge-Kutta method. Results show that the controller attenuated the hull's vibration, achieved an accurate position control of the shelf transfer manipulator, and has good robustness.

Dynamics Model of Elastic Underacutated Robot in a Non-inertial Frame and Its Applicaitons

Geng Mingchao, Zhao Tieshi, Zhao Fei, Liu Xiao, Yuan Feihu,

2014, 25(15):  2080-2085. 

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A dynamics model of elastic underacutated robot in a non-inertial frame was established based on screws. Firstly, the acceleration mapping of robot which was in inertia frame was obtained referring to the Lie bracket of two screws. The acceleration mapping in a non-inertia frame was deducted through the transformation of the rigid-body velocity and acceleration in different frames. Then the dynamics model of robot in a non-inertia frame was obtained using the rigid-body Newton-Euler equation. The dynamics model is simple because of the use of the twist and wrench in the process of derivation. Finally, the aerial refueling system, which was a typical application of an elastic underactuated robot in a non-inertia frame, was taken as an example. The dynamics model of the system was presented, and was verified by dynamics simulation software, which demonstrates the correctness and feasibility of the theoretical analysis.

Pose Adjustment of Cutting Tools for Regrinding Based on Planar Displaying Method and Multi-joint Linkage

Huang Ruofeng, Xiong Liangshan, Bi Huangsheng

2014, 25(15):  2086-2090. 

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When cutting tools was grinded in the tool grinding machine,adjustment of the pose of the surface to be ground  involved complicated multi-joint linkage of planes in space, and calculation of the adjustment angle was a problem which was difficult to solve with general method. With the planar displaying method, the image point of the cutter surface for grinding in projective plane was established. This paper presented a method which transformed the rotation of planes in space into the movement of the image points in projective plane, and then used the universal clip to realize pose adjustment of the cutter surface for grinding, and the relevant calculation formulas were given. The sharpening experiments show that the proposed method can easily sharpen the single point tool with different combination of cutting angles.

Numerical Study of Wear Process on Pipe Wall in Concrete Pumping Using DEM

Tan Yuanqiang, Song Junhua, Zhang Hao, Wang Jiaqian, Deng Rong, Yang Dongmin

2014, 25(15):  2091-2097. 

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A discrete element model of fresh concrete was established and validated by L-box flow test of fresh concrete with physical parameters verified. Then the model and obtained parameters were used to simulate the concrete pumping process, where the impact forces on pipe wall were calculated and drawn to stand for the wear situation on the walls, the location of the puncture point was predicted. The effect of pumping speed and pipe bend were addressed. The statistic results were validated by comparing the numerical results with an actual broken bend, which indicates that the wear on the pipe wall increases with pumping speed and degree of pipe bend.

Research on Cylindricity Prediction and Process Parameter Optimization in Honing Based on Response Surface Methodology

Hu Xiaoping, Xi Changqing, Yu Baohua

2014, 25(15):  2098-2101,2106. 

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It is beneficial for determining the process parameters quickly and improving the machining precision to set up a prediction model of cylindricity associated with honing process parameters. The experimental plan was designed by the method of quadratic general rotation union. Based on the experiments a prediction model of cylindricity was built, which was related with the stroke of honing tool, the pressure of honing, the rotary speed and the amount of finish. Analyzed with Design-Expert8.0 the prediction model was optimized. Quadratic response surfaces were given to exposing the relationship of the honing process parameters and the cylindricity of hole. And the optimized process parameters were decided. Some other experiments indicate that the prediction model is reliable, and the optimized process parameters are effective.

Influences of Material Properties on Welding Formation in Friction Stir Welding

Lu Huang, Xing Li, Yang Chenggang, Huang Chunping, Ke Liming

2014, 25(15):  2102-2106. 

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The 2024-O and 2024-T4 aluminum alloy were welded by friction stir welding with column lefthand-thread pins, and the influences of the material properties on the friction stir weld formation was investigated. Soft constraints were applied to explain the impact of the material properties on the size of nugget. The results show that the weld morphology is constrained by the surroundings of nugget, and the constraints are related to material properties and weld temperature. Under the same heat-treated state material, the area and width of the nugget of 2024-O aluminum alloy are greater than that of 2024-T4 aluminum alloy, due to the smaller constraint of lateral migration of plastic metal by the soft constraint body. While 2024-O aluminum alloy and 2024-T4 aluminum were welded with butt welding, taking the higher strength of 2024-T4 aluminum alloy as the retreated side, the constraint of the advanced side are stronger than the constraint of retreated side by both sides of the welding' soft constraint body, and the welding nugget is moved to the retreated side; the direction up of movement trend of the welding nugget which is made along the weld thickness is enhanced owing to the more plastic metal of retreated side, the welding nugget height of retreated side is higher than that of advanced side. Under the appropriate preheating conditions of 2024-T4 aluminum alloy, due to the increasing of plasticized metal in the weld and transverse migration of plastic metal，the width and area of the nugget are increased.

Study on Fatigue Property of Auto Seam Welded Thin-sheet Structures

Kou Hongbin, Qiu Rongying, Zhu Jianfeng

2014, 25(15):  2107-2111. 

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The fatigue evaluation of metal active gas(MAG)-welded thin-sheet structure is the main problem for chassis structure design, fully understand and master the fatigue property of thin-sheet structure is the foundation to predict the fatigue life. Through a series of sheet welded structure fatigue tests, some laws were summarized, that shows the effects of sheet metal strength, sheet metal thickness and welding manufacturing process on the weld fatigue performance, it makes a solid foundation for MAG-welded thin-sheet structure fatigue resistance design.

Reconstruction Methods of Vehicle Road Spectrum Faced Users

Liu Yongchen, Wang Guolin, Sun Li, Shao Changzheng

2014, 25(15):  2112-2116. 

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In order to determine the road motivation accurately for the vehicle and road coupling dynamics, a road spectrum acquisition method was presented based on the actual users. Roads spectrum data was acquired by using multifunction laser pavement detector according to the needs of car users, and the road elevation data was preprocessed by removing the singular value, the smooth connection, multi-octave filter. The user typical road spectrum and grade power spectrum were acquired by the power spectral density analysis and calculation. A road domain spectrum of user need was reconstructed by application Caroad software system, and simulation road spectrum were generated, which could be used in ADAMS, the VPG, of Carsim software and road spectrum reconstruction precision were analyzed with the correlation coefficient method. By instance analysis, three-dimensional road spectrum was obtained that meets user's requirements, and the road spectrum reconstruction precision is better.

Reanalysis of Large Scale Vehicle Structure Based on GPU

He Guanqiang, Wang Hu, Huang Guanxin, Li Guangyao

2014, 25(15):  2117-2123,2129. 

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Combined approximation (CA) was commonly used in structural reanalysis. However, with the increasing complexity and scale of the engineering problems, the classical CA could not be used directly due to huge decrease in computational efficiency. To overcome such bottleneck for large-scale reanalysis problem, the CA procedure was reconstructed to accommodate the use of GPU by employing CUDA programming model, and then a GPU-based reanalysis system was established. Some important issues of the reanalysis, such as assembly of stiffness matrix, inverse of equilibrium equations were parallelized and optimized. To verify the performance of the suggested system and algorithms, stiffness analysis of frame and door of a vehicle were implemented successfully. Finally, the results demonstrate that the efficiency of the reanalysis is improved significantly and the accuracy of the simulated results is also promised.

Low Frequency Noise Analysis and Control of Excavator Cab

Chen Jian, Jiang Fengxin, Xiao Yue

2014, 25(15):  2124-2129. 

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The structural FE(finite element) model and acoustic BE model of one excavator cab were established. The excitation loads of the cab in working condition were solved on the basis of inverse matrix method in frequency domain. Vibration velocity response of vehicle cab was obtained through modal-based forced response method. Taking the above velocity as the boundary condition, the sound pressure at driver's right ear was calculated by combining BE method with ATV method, and the results were verified by tests. The panel contribution most to the peek sound pressure was found out by panel contribution analysis and optimized through topography optimization method and adding damping treatment. And the result shows a significant decrease of peak value of the interior sound pressure level of the cab.