Ren G Dong

National Institute of Occupational Safety and Health, USA · Human Health and Service

Findings from epidemiological studies suggest that occupational exposure to whole-body vibration (WBV) may increase the risk of miscarriage and contribute to a reduction in fertility rates in both men and women. However, workers exposed to WBV may also be exposed to other risk factors that contribute to reproductive dysfunction. The goal of this ex...

Prolonged and intensive vibration exposures during the grinding of handheld workpieces may cause hand-arm vibration syndrome. The objectives of this study are to develop an on-the-hand method for evaluating vibration-reducing (VR) gloves, and to determine whether VR gloves can significantly reduce the vibration exposures. A worker holding and press...

Studies on hand-transmitted vibration exposure, biodynamic responses, and biological effects were conducted by researchers at the Health Effects Laboratory Division (HELD) of the National Institute for Occupational Safety and Health (NIOSH) during the last 20 years. These studies are systematically reviewed in this report, along with the identifica...

In the framework of whole-body vibration (WBV), biodynamics refers to biomechanical responses of the human body to impressed oscillatory forces or motions. The biodynamic responses of the human body to WBV form an essential basis for an understanding of mechanical-equivalent properties of the body and potential injury mechanisms, developments in fr...

The objective of this study was to develop a vibration model of a grinding machine-workpiece-hand-arm system. A lumped-parameter model structure of the system was proposed, and its major parameters were determined using the mechanical impedance measured at the grinding point of a typical workpiece (golf club head) held by two hands and referenced t...

Percussive riveting is the primary process for attaching the outer sheet metal "skins" of an aircraft to its airframe. Workers using manually-operated riveting tools (riveting hammers and rivet bucking bars) are exposed to significant levels of hand-transmitted vibration (HTV) and are at risk of developing components of hand-arm vibration syndrome...

Background: The annual incidence rate of work-related upper extremity musculoskeletal disorders (WUEMSDs) is increasing in US workers according to the United States Bureau of Labor Statistics (BLS). However, the prevalence of WUEMSDs among US total workers has not been estimated. Objective: We aimed to estimate the prevalence of WUEMSDs among US...

Using a simulated riveting approach, this study investigated the effects of feed force on the vibrations measured on several typical rivet bucking bars and that transmitted to the bucking bar operator’s wrist.

This study conducted two series of experiments to investigate the relationships between hand coupling force and biodynamic responses of the hand-arm system. In the first experiment, the vibration transmissibility on the system was measured as a continuous function of grip force while the hand was subjected to discrete sinusoidal excitations. In the...

Background According to the US Bureau of Labor Statistics, musculoskeletal disorders (MSDs) accounted for 32% of all nonfatal injury and illness cases in 2014 among full-time workers. Our objective was to review and summarize the evidence linking occupational exposures to vibration and awkward posture with MSDs of the shoulder and neck. Methods A...

Mast Climbing Work Platforms (MCWPs) are becoming more common at construction sites and are being used as an alternative to traditional scaffolding. Although their use is increasing, little to no published information exists on the potential safety hazards they could pose for workers. As a last line of defense, a personal fall-arrest system can be...

It is known that the vibration characteristics of the fingers and hand and the level of grip action interacts when operating a power tool. In the current study, we developed a hybrid finger model to simulate the vibrations of the hand–finger system when gripping a vibrating handle covered with soft materials. The hybrid finger model combines the ch...

To control vibration-induced white finger among workers performing the fine grinding of golf club heads, the aims of this study are to clarify the major vibration sources in the grinding process, to identify and understand the basic characteristics of the club head vibration, and to propose potential approaches for reducing the vibration exposure....

Background: Fingers-transmitted vibration can cause vibration-induced white finger. The effectiveness of vibration-reducing (VR) gloves for reducing hand transmitted vibration to the fingers has not been sufficiently examined. Objective: The objective of this study is to examine tool-specific performance of VR gloves for reducing finger-transmit...

Mechanical arm systems are commonly used to support powered hand tools to alleviate ergonomic stressors related to the development of workplace musculoskeletal disorders. However, the use of these systems can increase exposure times to other potentially harmful agents such as hand-transmitted vibration. To examine how these tool support systems aff...

While simulations of the measured biodynamic responses of the whole human body or body segments to vibration are conventionally interpreted as summaries of biodynamic measurements, and the resulting models are considered quantitative, this study looked at these simulations from a different angle: model calibration. The specific aims of this study a...

The hand coordinate systems for measuring vibration exposures and biodynamic responses have been standardized but they are not actually used in many studies. This contradicts the purpose of the standardization. The objectives of this study were to identify the major sources of the problem and to help define or identify better coordinate systems for...

The objective of this study is to evaluate an adapter method for measuring the vibration on the human arms. Four instrumented adapters with different weights were used to measure the vibration transmitted to the wrist, forearm, and upper arm of each subject. Each adapter was attached at each location on the subjects using an elastic cloth wrap. Two...

Anti-vibration gloves have been used to block the transmission of vibration from powered hand tools to the user, and to protect users from the negative health consequences associated with exposure to vibration. However, there are conflicting reports as to the efficacy of gloves in protecting workers. The goal of this study was to use a characterize...

Relevance to industry: Prolonged, intensive exposure to hand-transmitted vibration could result in hand-arm vibration syndrome. While the syndrome's precise mechanisms remain unclear, the characterization of the vibration transmissibility of the system in the three orthogonal dimensions performed in this study can help understand the syndrome and...

For exposure to hand-transmitted vibration (HTV), personal protective equipment is sold in the form of anti-vibration (AV) gloves, but it remains unclear how much these gloves actually reduce vibration exposure or prevent the development of hand-arm vibration syndrome in the workplace. This commentary describes some of the issues that surround the...

Sheet metal workers operating rivet bucking bars are at risk of developing hand and wrist musculoskeletal disorders associated with exposures to hand-transmitted vibrations and forceful exertions required to operate these hand tools. New bucking bar technologies have been introduced in efforts to reduce workplace vibration exposures to these worker...

Relevance to industry: Hand-transmitted vibration exposure may cause hand-arm vibration syndrome. Vibration-reducing gloves are considered as an alternative approach to reduce the vibration exposure. This study provides useful information on the effectiveness of the gloves when used with many tools for reducing the vibration transmitted to the pal...

Contact interactions between the hand and handle, such as the contact surface softness and contact surface curvature, will affect both physical effort and musculoskeletal fatigue, thereby the comfort and safety of power tool operations. Previous models of hand gripping can be categorized into two groups: multi-body dynamic models and finite element...

Relevance to industry: Prolonged, intensive exposure to hand-transmitted vibration can cause hand-arm vibration syndrome. Vibration-reducing gloves have been used as an alternative approach to reduce the vibration exposure. However, their effectiveness for reducing finger-transmitted vibrations remains unclear. This study enhanced the understandin...

The use of a handheld adapter equipped with a tri-axial accelerometer is the most convenient and efficient approach for measuring vibration exposure at the hand-tool interface, especially when the adapter is incorporated into a miniature handheld or wrist-strapped dosimeter. To help optimize the adapter approach, the specific aims of this study are...

The relationship between the vibration transmissibility and driving-point response functions (DPRFs) of the human body is important for understanding vibration exposures of the system and for developing valid models. This study identified their theoretical relationship and demonstrated that the sum of the DPRFs can be expressed as a linear combinat...

Vibration-reducing (VR) gloves are commonly used as a means to help control exposures to hand-transmitted vibrations generated by powered hand tools. The objective of this study was to characterise the vibration transmissibility spectra and frequency-weighted vibration transmissibility of VR gloves at the palm of the hand in three orthogonal direct...

Research regarding the risk of developing hand-arm vibration syndrome after exposure to impact vibration has produced conflicting results. This study used an established animal model of vibration-induced dysfunction to determine how exposure to impact vibration affects peripheral blood vessels and nerves. The tails of male rats were exposed to a si...

The objectives of this study were to develop models of the hand–arm system in the three orthogonal directions (xh, yh, and zh) and to enhance the understanding of the hand vibration dynamics. A four-degrees-of-freedom (DOF) model and 5-DOF model were used in the simulation for each direction. The driving-point mechanical impedances distributed at t...

Occupational exposure to vibration through the use of power- and pneumatic hand-tools results in cold-induced vasospasms, finger blanching, and alterations in sensorineural function. Collectively, these symptoms are referred to as hand-arm vibration syndrome (HAVS). Currently the International Standards Organization (ISO) standard ISO 5349-1 contai...

The objective of this study is to propose a theory on the biodynamic frequency weighting for studying hand-transmitted vibration exposures and vibration-induced effects. We hypothesize that the development of a vibration effect is the result of two consecutive but synergistic processes: biodynamic responses to input vibration and biological respons...

Unlabelled: Motorized vibrating manure forks were used in beach-cleaning operations following the massive Deepwater Horizon oil spill in the Gulf of Mexico during the summer of 2010. Objectives: The objectives of this study were to characterize the vibration emissions of these motorized forks and to provide a first approximation of hand-transmit...

The use of riveting hammers can expose workers to harmful levels of hand-transmitted vibration (HTV). As a part of efforts to reduce HTV exposures through tool selection, the primary objective of this study was to evaluate the applicability of a standardized laboratory-based riveting hammer assessment protocol for screening riveting hammers. The se...

The Jamar handle dynamometer is the most commonly used instrument for measuring grip strength. However, the grip strength applied on a cylindrical handle may not exhibit the same handle size relationship as that observed with the Jamar handle. Direct comparison studies are required to clearly identify the major differences between the two dynamomet...

The objective of this study is to investigate the basic characteristics of the three axis mechanical impedances distributed at the fingers and palm of the hand subjected to vibrations along the three orthogonal directions (xh, yh, and zh). Seven subjects participated in the experiment on a novel three-dimensional (3-D) hand–arm vibration test syste...

To improve the reliability of the anti-vibration (AV) glove test defined in the current standard, a revised version of the standard has been proposed. However, the revised method has not been fully tested and sufficiently evaluated, and it is unknown whether it is practically feasible and convenient to implement the standard. To help achieve the ob...

The tip-over of scissor lifts in operation has frequently resulted in the death and/or severe injuries of workers. The ob-jective of this study is to enhance the understanding of its major mechanisms and factors influencing scissor lift stability. Both experimental and modeling approaches were used in this study. Two series of experiments were perf...

Air-cushioned gloves have the advantages of lighter weight, lower cost, and unique mechanical performance, compared to gloves made of conventional engineering materials. The goal of this study is to analyze the contact interaction between fingers and object when wearing an air-cushioned glove. The contact interactions between the the fingertip and...

Prolonged, intensive exposure to vibrations from palm and orbital sanders could cause finger disorders. They are likely to be associated with the biodynamic responses of the fingers. Although the biodynamic responses of the hand-arm system have been studied by many researchers, the detailed biodynamic responses distributed in the hand substructures...

The specific mechanisms of the biodynamic effects is found and the optimized design of the adaptor and its hand-holding strategy is found so that the undesired effects could be minimized. Three adapters were considered and experiment was carried out on a hand-arm vibration test system equipped with an instrumented handle that can measure the tri-ax...

The vibration transmissibility on the human hand-arm system subjected to vibrations in three orthogonal directions was investigated. Seven healthy male subjects participated in the study and the experiment was carried out on a novel 3-D vibration test system. The vibration controller was programmed to generate broadband random vibration in the freq...

Gloves with anti-vibration features are increasingly used to reduce impact vibrations or shocks transmitted to the hands of power tool operators. Selection and evaluation of the glove materials are important steps in the designs of such gloves. In the current study, we proposed an approach to objectively evaluate the effectiveness of the glove mate...

In the current study, we hypothesize that the vibration power absorption density (VPAD) is a good measure for the vibration exposure intensity of the soft tissues of the fingers. In order to calculate the VPAD at a fingertip, we proposed a hybrid modeling approach, which combines a 2D finite element (FE) model with a lumped parameter model. Whereas...

Identification of most probable ranges of biodynamic responses of the human body exposed to whole-body vibration is essential for developing effective integrated human-machine system design tools, improved vibration mitigation devices and frequency-weighting for exposure assessment. The international standard, ISO-5982 (2001), defines such ranges f...

The major objectives of this study were to establish an alternative method for measuring the effects of gloves on the grip strength applied to cylindrical handles and to quantify the strength reduction due to the use of typical anti-vibration (AV) gloves. Different from previous studies that measure the grip force in a specific plane, the alternati...

The biodynamic response functions of the human whole-body system measured with subjects participating in an experiment are commonly arithmetically averaged and used to represent their mean response functions in many studies. The reported means were further averaged to form the reference means for standardization and various applications. The object...

Available experimental data of the dynamic force at a rail joint are used to validate the Discrete Support (DS) model of vehicle-track system. The validated DS model is employed to investigate the characteristics of dynamic forces due to a dipped rail joint. The results show that increasing axle load and rail equivalent mass significantly increases...

The major objective of this study is to develop a modeling method for estimating the biodynamic responses distributed at the fingers and the palm of the hand based on the total driving-point mechanical impedance of the entire hand–arm system. A five degrees-of-freedom (DOF) model with a set of constraints proposed in this study was used in the esti...

Biomechanical models of the hand and fingers are useful tools for hand surgeons to improve surgical procedures and for biomedical researchers to explore the mechanical loading in the musculoskeletal system that cannot be easily measured in vivo. The purpose of the present study was to develop a realistic index finger model for solving practical pro...

Vibration-induced biodynamic responses (BR) of the human hand–arm system measured with subjects participating in an experiment are usually arithmetically averaged and used to represent their mean response. The mean BR data reported from different studies are further arithmetically averaged to form the reference mean response for standardization and...

The interaction between the handle and operator's hand affects the comfort and safety of tool and machine operations. In most of the previous studies, the investigators considered only the normal contact forces. The effect of friction on the joint moments in fingers has not been analyzed. Furthermore, the observed contact forces have not been linke...

To provide a means for comparing impact wrenches and similar tools, the international standard ISO 8662-7 prescribes a method for measuring the vibrations at the handles of tools during their operations against a cotton-phenolic braking device. To improve the standard, alternative loading mechanisms have been proposed; one device comprises aluminum...

The primary objectives of the current study are to enhance the understanding of the mechanisms of the anti-vibration gloves and to evaluate the methods for assessing their vibration isolation effectiveness through developing a mechanical-equivalent model of the glove-hand–arm system. The model is developed based on the measured driving-point mechan...

The objective of this study is to enhance the understanding of the hand grip force applied to a cylindrical handle and to develop a new dynamometer for measuring maximum grip force or grip strength. Specifically, a 40 mm instrumented cylindrical handle with six measuring arms was developed. A theoretical model was proposed and used to analyze the p...