Maximum Transient Vibration Value Research Articles

Ride Comfort Prediction on Urban Road Using Discrete Pavement Roughness Index

The prediction of ride comfort holds significant potential for enhancing the driving experience of both human drivers and autonomous vehicles, as it is closely correlated with pavement roughness. However, in urban road scenarios, the presence of shorter road segments and local irregularities introduces added complexity to ride comfort prediction. To better capture and characterize the irregularities and short road sections’ unevenness, we adopt the discrete roughness index (DRI) instead of the commonly used international roughness index (IRI) for assessing road profile unevenness, which is more suitable for urban roads. Ride comfort prediction is developed through numerical simulations using an eight-degree-of-freedom full-car model. The maximum transient vibration value (MTVV) is adopted to assess ride comfort. Through comparing the correlations between the MTVV and pavement roughness indices, it is indicated that the fitting degree of MTVV-DRI outperforms that of MTVV-IRI on short sections. Then, a set of speed-related DRI thresholds to estimate ride comfort distribution on a given road section is proposed, with considerations of vehicle speed, time period, and wheel paths. A hyperbolic-tangent-based speed control strategy is also proposed to avoid abrupt speed and acceleration changes during deceleration. This prediction method can assist drivers or autonomous vehicles in generating driving control strategies and maintaining a high level of ride comfort.

Vibration Behavior of Composite Cold Formed Steel Floors with Concrete Topping due to Heel-Drop Loading

Human-induced vibration is an important serviceability issue of modern structural designs, especially for light long-span structures. The common heel-drop impact is usually considered in evaluating the vibration of cold-formed steel (CFS) floors. This paper proposes a simplified equation for determining the peak accelerations under transient impacts, based on the Duhamel integral. The analytical results were validated with a comparison with the results from the heel-drop test results on a CFS floor of 3 900[Formula: see text]mm × 5 600[Formula: see text]mm (at both construction and completion stages). The dynamic responses of the floor, including peak acceleration, maximum transient vibration value (MTVV), and crest factor (a ratio of MTVV-to-peak acceleration) were analyzed in detail. The natural frequencies of the floor were obtained from the FFT and FRF analysis of heel-drop and hammering test results. The investigated on-site composite CFS floor with concrete topping was found to have a high fundamental frequency: 17[Formula: see text]Hz at the construction stage and 21[Formula: see text]Hz at the completion stage. In determining the fundamental frequency of the CFS floor, the hammering was thought to be more effective than the heel-drop owing to the phenomenon of human-structure interaction (HSI). Moreover, finite element analyses were performed to study the effects of profiled steel sheeting type (Types 28-100-800, 21-180-900, and 14-80-640) and concrete thickness (40, 50, 60, 70, 80, 90, and 100[Formula: see text]mm). With the SCSC condition (two opposite edges clamped and the other two edges simply-supported), the peak acceleration decreased by 50% when the concrete thickness increased from 40[Formula: see text]mm to 100[Formula: see text]mm.

Development of an innovative three-dimensional vibration isolation bearing

This paper presented an innovative three-dimensional vibration isolation bearing (3D-VIB) to mitigate horizontal seismic action and rail-induced vertical vibration. The 3D-VIB was composed of a thick laminated rubber bearing acting as the vertical vibration isolation module and a friction pendulum acting as the horizontal seismic isolation module. The thick laminated rubber bearing was used as a part of the slider in the friction pendulum. The compression performance of 3D-VIB was decoupled from its shear performance by concentrating the compressive deformation into the thick rubber bearing while shear deformation occurred independently in the friction pendulum module. The bearing capacity, vertical and horizontal properties of a full-scale 3D-VIB specimen were tested. In the test, the ultimate bearing capacity of 3D-VIB was 7 times that of the design compressive load of normal service condition. The vertical stiffness of the specimen under seismic vibration and vertical rail-induced vibration were tested separately. It was found that the vertical stiffness of the specimen under rail-induced vibration was 1.55 times higher than the vertical stiffness under seismic vibration. The horizontal performance of the 3D-VIB was characterized by stable parallelogram-shaped hysteretic curves similar to that of the traditional friction pendulum system. A user-defined element was developed and incorporated into ABAQUS to simulate the mechanical behavior of the 3D-VIB under different loading conditions, and simulation results agreed with the test results. The responses of a steel structure equipped with the 3D-VIB, while subjected to earthquake ground motions and rail-induced vibrations, respectively, were analyzed and compared with the non-isolated one. The analysis results suggested that with the installation of the 3D-VIB, the maximum inter-story drift ratio of the structure under maximum considered earthquake was reduced by about 88%. The average maximum transient vibration value of the rail-induced vertical vibration at the typical points of the conventional model was 86.2 dB, while that in the 3D-isolated model was 78.6 dB, the vibration reduction was 7.6 dB.

Study on the vibration evaluation method and allowable differential settlement of road-bridge transition section with full-car model

ABSTRACT The differential settlement between bridge approach slab and abutment causes bump problems when vehicles passing this area. This study aims at evaluating the roughness of area between road-bridge transition properly and putting forward the allowable differential settlement value based on the comfortable feeling of passengers. In this research, the maximum transient vibration value (MTVV) was chosen to be the evaluation index of roughness vibration comfort, and full-car model and bridge approach pavement models were established using Carsim software. Then, the interactions of human-vehicle-road were simulated when the car passed the bridge at different speeds, and the influences of step height, approach slab length, approach relative slope and vehicle speed on MTVV were studied. According to the simulation results and the comfortable feeling questionnaire when a testing car passed different bridge areas, the specific grading standard of MTVV was given, and for the bridge with and without approach slab, the allowable differential slope and the step height of the bridge under difference were put forward. The results have a significant value for the roughness evaluation of the road-bridge transition area and can be used to judge whether this area is needed or not to maintain.

Vibration behavior of large span composite steel bar truss-reinforced concrete floor due to human activity

Human-induced vibration could present a serious serviceability problem for large-span and/or lightweight floors using the high-strength material. This paper presents the results of heel-drop, jumping, and walking tests on a large-span composite steel rebar truss-reinforced concrete (CSBTRC) floor. The effects of human activities on the floor vibration behavior were investigated considering the parameters of peak acceleration, root-mean-square acceleration, maximum transient vibration value (MTVV), fundamental frequency, and damping ratio. The measured field test data were validated with the finite element and theoretical analysis results. A comprehensive comparison between the test results and current design codes was carried out. Based on the classical plate theory, a rational and simplified formula for determining the fundamental frequency for the CSBTRC floor is derived. Secondly, appropriate coefficients (Brp) correlating the MTVV with peak acceleration are suggested for heel-drop, jumping, and walking excitations. Lastly, the linear oscillator model (LOM) is adopted to establish the governing equations for the human-structure interaction (HSI). The dynamic characteristics of the LOM (sprung mass, equivalent stiffness, and equivalent damping ratio) are determined by comparing the theoretical and experimental acceleration responses. The HSI effect will increase the acceleration response.

Drivers’ visual load at different time periods in entrance and exit zones of extra-long tunnel

Objective As the number of tunnels and traffic accidents increase, it is necessary to study the drivers’ visual characteristic in the tunnels. Considering that freeway tunnels have limited space and narrow sight zone, drivers usually have a short visual blind zone and visual shock when entering and exiting the tunnels. This study aims to investigate the characteristics of drivers’ visual load in the entrance and exit zones of extra-long tunnels, and to provide a theoretical basis for the traffic safety prevention and control measures of the engineering design. Methods 20 drivers were enrolled to conduct real vehicle tests in the Guizhou Sifangdong Tunnel at different time periods (daytime, twilight, and nighttime). The drivers’ pupil area was collected by an eye tracker. The maximum transient vibration value (MTVV) of the pupil area was selected as the index of visual load. In addition, the changing characteristics of visual load in the entrance and exit zones were examined. Using ANOVA, the significant difference of visual load in different zones and at different time periods were performed. Accordingly, the overall drivers’ visual load in the entrance and the exit zones were compared. Exponential function models of the MTVV value and the speed of pupil area change were constructed, where the pattern of mutual influence was examined. Results The changing pattern of the drivers’ visual load at different time periods in the entrance and exit zones were markedly different. The comparison of the overall visual load was as follows: exit zones at nighttime > entrance zones at nighttime > entrance zones at twilight > exit zones at twilight ≈ entrance zones at daytime ≈ exit zones at daytime. Moreover, the MTVV value positively correlated with the speed of the pupil area change. Finally, this study proposes an evaluation standard of visual comfort based on the speed of the pupil area change. Conclusion This study highlights the driving risk in extra-long tunnel. These findings could provide a basis for studying the setting method of visual guidance facilities in entrance and exit zones of extra-long tunnel. Also, this study could provide a theoretical basis for the evaluation of drivers’ visual load in the tunnel.

Developing artificial neural networks to estimate real-time onboard bus ride comfort

The ride comfort of bus passengers is a critical factor that is recognised to attract greater ridership towards a sustainable public transport system. However, it is challenging to estimate bus passenger comfort onboard while travelling due to the complex non-linear interaction among various factors. A practicable method to collect real-time comfort ratings by passengers is also not readily available. This study developed an artificial neural network (ANN) model with three layers to precisely estimate real-time ride comfort of bus passengers. The inputs are vehicle-related parameters (speed, acceleration and jerk), passenger-related features (posture, location, facing, gender, age, weight and height), ride comfort index in ISO 2631-1997 (vibration dose value and maximum transient vibration value), and output is passenger rating (collected from a specialised mobile application). The ANN model provided a satisfactory performance and good correlation between inputs and output with an average MSE = 0.03 and R-value = 0.83, respectively. Sensitivity analysis was also conducted to quantify the relative contribution of each variable in the ANN model, revealing similar contributions among all influencing factors in the range of 4–6%. On average, passenger-related factors contribute slightly higher than vehicle-related factors to the ride comfort estimation based on the connection weight approach. The development of ANN model which can precisely estimate bus ride comfort is important as a considerable amount of machine learning and artificial intelligence are utilised to guide autonomous bus (AB). The present findings can help AB designers and engineers in improving AB technology to achieve a higher level of passengers’ onboard comfort.

Artificial neural network predication and validation of optimum suspension parameters of a passive suspension system

This paper presents the modeling and optimization of quarter car suspension system using Macpherson strut. A mathematical model of quarter car is developed, simulated and optimized in Matlab/Simulink® environment. The results are validated using test rig. The suspension system parameters are optimized using a genetic algorithm for objective functions viz. vibration dose value (VDV), frequency weighted root mean square acceleration (hereafter called as RMS acceleration), maximum transient vibration value, root mean square suspension space and root mean square tyre deflection. ISO 2631-1 standard is adopted to assess ride and health criterion. Results shows that optimum parameters provide ride comfort and health criterions over classical design. The optimization results are experimentally validated using quarter car test setup. The genetic algorithm optimization results are further extended to the artificial neural network simulation and prediction model. Artificial neural network model is carried out in Matlab/Simulink® environment and Neuro Dimensions. Simulation, experimental and predicted results are in close correlation. The optimized system reduces the values of VDV by 45%. Also, RMS acceleration is reduced by 47%. Thus, the optimized system improved ride comfort by reducing RMS acceleration and improved health criterion by reducing the VDV. Finally ANN can be used for predicting the optimum suspension parameters values with good agreement.

Vibration Behavior and Serviceability of Arched Prestressed Concrete Truss Due to Human Activity

The current trend toward longer spans and lighter floor systems, combined with reduced damping and new activities, have resulted in an increasing complaints on floor vibration from building owners and occupants. Heel-drop, jumping, and walking impacts, which may lead to discomfort problems in daily life, were imposed on a large-span arched prestressed concrete truss (APT) girder system studied. The natural frequencies, peak acceleration, average root-mean-square acceleration (ARMS), maximum transient vibration value (MTVV), and perception factor for the girder were obtained and checked against the existing codes and standards. The purpose of this paper is to provide researchers and engineers with a detailed evaluation on the vibration behavior of the APT girder under different human activities, with a comprehensive review on the relevant criteria and some suggestions. Lastly, the following threshold peak accelerations are suggested: 650[Formula: see text]mm/s2for transient heel-drop impact, 1450[Formula: see text]mm/s2for transient jumping impact, and 250[Formula: see text]mm/s2for steady-state walking. In addition, the threshold values of 90[Formula: see text]mm/s2and 50[Formula: see text]mm/s2are suggested for MTVV and ARMS, respectively, under steady-state walking.

Whole-Body Vibrations Associated With Alpine Skiing: A Risk Factor for Low Back Pain?

Alpine skiing, both recreational and competitive, is associated with high rates of injury. Numerous studies have shown that occupational exposure to whole-body vibrations is strongly related to lower back pain and some suggest that, in particular, vibrations of lower frequencies could lead to overuse injuries of the back in connection with alpine ski racing. However, it is not yet known which forms of skiing involve stronger vibrations and whether these exceed safety thresholds set by existing standards and directives. Therefore, this study was designed to examine whole-body vibrations connected with different types of skiing and the associated potential risk of developing low back pain. Eight highly skilled ski instructors, all former competitive ski racers and equipped with five accelerometers and a Global Satellite Navigation System to measure vibrations and speed, respectively, performed six different forms of skiing: straight running, plowing, snow-plow swinging, basic swinging, short swinging, and carved turns. To estimate exposure to periodic, random and transient vibrations the power spectrum density (PSD) and standard ISO 2631-1:1997 parameters [i.e., the weighted root-mean-square acceleration (RMS), crest factor, maximum transient vibration value and the fourth-power vibration dose value (VDV)] were calculated. Ground reaction forces were estimated from data provided by accelerometers attached to the pelvis. The major novel findings were that all of the forms of skiing tested produced whole-body vibrations, with highest PSD values of 1.5–8 Hz. Intensified PSD between 8.5 and 35 Hz was observed only when skidding was involved. The RMS values for 10 min of short swinging or carved turns, as well as all 10-min equivalent VDV values exceeded the limits set by European Directive 2002/44/EC for health and safety. Thus, whole-body vibrations, particularly in connection with high ground reaction forces, contribute to a high risk for low back pain among active alpine skiers.

Psycho-vibratory evaluation of timber floors – Towards the determination of design indicators of vibration acceptability and vibration annoyance

In timber housing constructions, vibrations can be a nuisance for inhabitants. Notably, the vibrational response of wooden floor systems is an issue in need of being dealt with more adequately in the designing of such buildings. Studies addressing human response to vibrations are needed in order to be able to better estimate what level of vibrations in dwellings can be seen as acceptable. In the present study, measurements on five different wooden floors were performed in a laboratory environment at two locations in Sweden (SP in Växjö and LU in Lund). Acceleration measurements were carried out while a person either was walking on a particular floor or was seated in a chair placed there as the test leader was walking on the floor. These participants filled out a questionnaire regarding their perception and experiencing of the vibrations in question. Independently of the subjective tests, several static and dynamic characteristics of the floors were determined through measurements. The ultimate aim was to develop indicators of human response to floor vibrations, specifically those regarding vibration acceptability and vibration annoyance, their being drawn based on relationships between the questionnaire responses obtained and the parameter values determined on the basis of the measurements carried out. To that end, use was made of multilevel regression. Although the sample of floors tested was small, certain clear trends could be noted. The first eigenfrequency (calculated in accordance with Eurocode 5) and Hu and Chui׳s criterion (calculated from measured quantities) proved to be the best indicators of vibration annoyance, and the Maximum Transient Vibration Value (computed on the basis of the accelerations experienced by the test subjects) to be the best indicator of vibration acceptability.

Evaluating Methods of Vibration Exposure and Ride Comfort in Car

Objective: This paper studies the method of measuring whole-body vibration in the car and terms associated. Background: Human exposure to vibration can be broadly classified as localized and whole-body vibration. The whole-body vibration affects the entire body of the exposed person. It is mainly transmitted through the seat surfaces, backrests, and through the floor to an individual sitting in the vehicle. It can affect the comfort, performance, and health of individuals. Method: Human responses to whole-body vibration can be evaluated by two main standards such as ISO 2631 and BS 6841. The vibration is measured at 8 axes - three translations at feet, 3 translations of hip and two translations of back proposed by Griffin. B&K"s sensors used in this study are the 3-axes translational acceleration sensor to measure the translational accelerations at the hip, back and foot. Results: The parameters associated with the whole-body vibration in the car are frequency weightings, frequency weighted root-mean-square, vibration dose values, maximum transient vibration value, seat effective amplitude transmissibility, ride values and ride comfort. Conclusion: Studied the evaluating methods of vibration exposure and ride comfort. Application: Evaluation of whole-body vibration in the car.

Measures of vibration exposure for a high-speed craft crew

The paper compares measurement-based measures for human vibration exposure. Data were collected during sea trials on a 10 m, 50 kn coastguard craft equipped with a three-axial accelerometer at the coxswain seat and with vertically mounted gauges measuring the acceleration of the cockpit floor. The ISO 2631-1:1997 measures of vibration (namely the root-mean-square (r.m.s.) value of the whole-body vibration (determined from the frequency-weighted acceleration signal), the maximum transient vibration value (MTVV), and the vibration dose value), the ISO 2631-5:2004 measure (namely the daily equivalent static compression dose Sed), and also statistically based measures to evaluate the acceleration magnitude are compared and discussed with respect to their ability to identify the mitigating effect of the suspension seat and how the different measures rank the severity of the high-speed craft (HSC) ride. The paper concludes that the r.m.s. value and the MTVV are unsuitable for evaluation of the conditions aboard while the other investigated measures show potential in this respect. Further the approach of ISO 2631-5:2004 taking both the short-term and the long-term perspectives on the human exposure to vibration is concluded to be the most mature method well suited to evaluation of HSC conditions.

Vibration and shock exposure of maintenance-of-way vehicles in the railroad industry

The aim of this study is to investigate and compare vibration and shock measurements of maintenance-of-way vehicles used in the railroad industry for track maintenance and construction. Following international standards (i.e., ISO 2631-1: 1997) and professional guidelines the frequency weighted root-mean-square (r.m.s.) acceleration for each measurement axis, the vector sum, the seat effective amplitude transmissibility (SEAT), the crest factor (CF), the maximum transient vibration value (MTVV), the vibration dose value (VDV), the ratio and the newly proposed shock risk estimation factor ‘ R’ for spinal injury according to ISO 2631-5:2004 were measured and calculated for seven different maintenance-of-way vehicles during revenue service. Furthermore, a proposed alternative spinal injury prediction method, the VibRisk model, which incorporates different typical driver postures and operator physical characteristics was included for comparison with the ISO 2631-5 risk prediction. The results of the vibration exposure measurements depended on vehicle type, track/surface conditions and seat properties, with the tamper and bulldozer showing the highest r.m.s. vibration values. The vector sum ( a v) results ranged from 0.37 to 0.99 (m/s 2). Five of seven track maintenance vehicles would exceed the current Whole-body Vibration ACGIH-TLV ® guideline for an 8 h exposure duration in the vertical axis recommended by the American Conference of Governmental Industrial Hygienists (ACGIH). The measured CF, MTVV/ a w and VDV/( a w· T 1/4) ratios were at or above the critical ratios in the majority of measurements given by the ISO 2631-1 (1997) and American industry guidelines by the American Conference of Governmental Industrial Hygienists (ACGIH-TLV). Comparing both prediction models for vibration shock risk for parts of the lumbar spine, different risk predictions and inconsistencies were found. The VibRisk model generally suggests different and higher risk of vertebral endplate failure for individual lumbar levels, whereas the ISO 2631-5 model indicated generally lower risks and did not differentiate between different disk levels and driver posture. Epidemiological studies validating the different shock risk models are lacking. Work modifications and adequate suspension seats would be beneficial for prevention of harmful exposure to vibration and shocks.

Evaluation of Vibration Assessment Criteria and Their Application to Stadium Serviceability

This paper explores the current recommended measures for assessing vibration serviceability in building structures and the recommendations for relating these vibration measures to levels of perception and expected occupant reactions. Two of these assessment measures, the maximum transient vibration value and vibration dose value, are discussed with respect to serviceability in stadium structures. The results of the monitoring and assessment of three stadium structures during several events are presented and these results indicate that the current recommendations are overly conservative in assessing occupant perception. Recommendations for vibration dose levels that are more consistent with the evaluation of events monitored in stadium structures are proposed.

Determination of Allowable Differential Settlement in Bridge Approach due to Vehicle Vibrations

The differential settlement between the bridge abutment and the approach embankment produces the common “bump at the end of the bridge.” This paper conducts a theoretical study on the determination of the allowable differential settlement. The maximum transient vibration value of the acceleration is recommended as the vibration comfort index. A dynamic response analysis to Man-Vehicle-Road system is carried out by means of the Laplace transform in which the vehicle is modeled as a three-degree-of-freedom system, and the bridge approaches with and without approach-relative slopes are simplified as broken lines model and step model, respectively. Parametric studies are carried out to find out what kind of effects some parameters such as the driving direction and running speed may have on the allowable differential settlement. Finally, the method and computational procedures to determine the allowable differential settlement are presented.

Prediction of vehicle discomfort from transient vibrations

Vehicle manufacturers are continuously seeking to improve vibration comfort. In this paper, subjective responses from transient vibrations in a forklift were analyzed on the basis of ISO 2631-1 and a number of additional variables. The objectives were to define: the effect of different operating conditions and appropriate background variables of subjects on perceived motions; the development of model that describes perceived discomfort as a function of measured vibrations; and important frequencies for prediction of vibration discomfort. The experiment was based on 12 different operating conditions defined by the variables: vehicle speed, obstacle height and load conditions. Eleven professional drivers participated and their responses of overall discomfort were defined by a vector sum of three perceived motions: shaking, for-aft and up-down motions. The evaluation method, maximum transient vibration value as defined in ISO 2631-1 was found to be adequate in predicting vibration discomfort during a four second transient vibration exposure. By analysis of narrow frequency band spectra of vibrations several explanations for the test results are discussed. The best results were obtained using a prediction model based on accelerations in 1 3 -octave bands of pitch vibrations.

The Effect of Seat Design on Vibration Comfort

A field study was done to evaluate different seat designs in the aspect of minimizing vibration transmission and reducing the level of discomfort experienced by drivers subjected to transient vibration. Two seat designs (sliding or fixed in the horizontal direction) were compared in an experiment based on variation of sitting posture, speed, and type of obstacle. The comparison was done by assessing discomfort and perceived motion and by vibration measurement. Ten professional drivers were used as participants. Maximum Transient Vibration Value and Vibration Dose Value were used in the evaluation. The results showed that a sliding seat is superior in attenuating vibration containing transient vibration in the horizontal direction. It was also perceived as giving less overall and low back discomfort compared to a fixed seat.

Whole-body vibration exposure study in U.S. railroad locomotives--an ergonomic risk assessment.

Whole-body vibration exposure of locomotive engineers and the vibration attenuation of seats in 22 U.S. locomotives (built between 1959 and 2000) was studied during normal revenue service and following international measurement guidelines. Triaxial vibration measurements (duration mean 155 min, range 84-383 min) on the seat and on the floor were compared. In addition to the basic vibration evaluation (aw rms), the vector sum (av), the maximum transient vibration value (MTVV/aw), the vibration dose value (VDV/(aw T1/4)), and the vibration seat effective transmissibility factor (SEAT) were calculated. The power spectral densities are also reported. The mean basic vibration level (aw rms) was for the fore-aft axis x = 0.18 m/sec2, the lateral axis y = 0.28 m/sec2, and the vertical axis z = 0.32 m/sec2. The mean vector sum was 0.59 m/sec2 (range 0.27 to 1.44). The crest factors were generally at or above 9 in the horizontal and vertical axis. The mean MTVV/aw was 5.3 (x), 5.1 (y), and 4.8 (z), and the VDV/(aw T1/4) values ranged from 1.32 to 2.3 (x-axis), 1.33 to 1.7 (y-axis), and 1.38 to 1.86 (z-axis), generally indicating high levels of shocks. The mean seat transmissibility factor (SEAT) was 1.4 (x) and 1.2 (y) and 1 (z), demonstrating a general ineffectiveness of any of the seat suspension systems. In conclusion, these data indicate that locomotive rides are characterized by relatively high shock content (acceleration peaks) of the vibration signal in all directions. Locomotive vertical and lateral vibrations are similar, which appears to be characteristic for rail vehicles compared with many road/off-road vehicles. Tested locomotive cab seats currently in use (new or old) appear inadequate to reduce potentially harmful vibration and shocks transmitted to the seated operator, and older seats particularly lack basic ergonomic features regarding adjustability and postural support.

COMPARISON OF SUBJECTIVE RESPONSES TO VIBRATION AND SHOCK WITH STANDARD ANALYSIS METHODS AND ABSORBED POWER

Evaluation of human exposure whole-body vibration (WBV) and shock can be carried out in a variety of ways. The most commonly used standards for predicting discomfort from WBV are BS6841 (1987) and ISO2631-1 (1997) which offer different frequency weightings (Wband Wk) and three methods of assessment: vibration dose value (VDV), estimated VDV (eVDV) and maximum transient vibration value (MTVV). Previous studies have also used DRI and absorbed power for assessments of shock and WBV. This paper reports a laboratory study in which 24 human subjects were exposed to 15 vertical vibration stimuli comprising of random vibration, repeated shocks and combinations of random vibration and shocks at 0·5, 1·0 and 1·5 m/s2r.m.s. Subjects rated the discomfort from the vibration on a numerical scale after each exposure. Acquired acceleration signals were analyzed using VDV, r.m.s. and MTVV for unweighted,Wb , Wkand DRI weighted signals. Acceleration and force were combined to give a measure of absorbed power. Subjective responses were correlated to vibration magnitude for the 13 analysis types. VDV was the best standard method of assessment; MTVV was the worst. Wband Wkfrequency weightings showed slightly greater correlations between vibration magnitude and discomfort than DRI weighted or unweighted signals. For VDV, there were no significant differences between the correlations obtained using any frequency weighting. For assessment of all stimuli types together, absorbed power gave higher correlations with subjective discomfort than acceleration-based methods. It is concluded that the methods described in ISO2631-1 should be clarified and simplified. Due to the difficulty in measuring absorbed power in the field, methods proposed in BS6841 are recommended as the most appropriate for assessment of discomfort from continuous vibration or repeated shocks.