Biodynamic Response of Human Fingers in a Power Grip Subjected to a Random Vibration

2004 ◽  
Vol 126 (4) ◽  
pp. 447-457 ◽  
Author(s):  
R. G. Dong ◽  
D. E. Welcome ◽  
T. W. McDowell ◽  
J. Z. Wu
Keyword(s):  
High Frequency ◽  
Random Vibration ◽  
Grip Force ◽  
Frequency Effect ◽  
Human Hand ◽  
Vibration Exposure ◽  
Power Grip ◽  
Coupling Force ◽  
Frequency Weighting ◽  
Male Subjects

Background. Knowledge of the biodynamic response (BR) of the human hand-arm system is an important part of the foundation for the measurement and assessment of hand-transmitted vibration exposure. This study investigated the BR of human fingers in a power grip subjected to a random vibration. Method. Ten male subjects were used in the experiment. Each subject applied three coupling actions to a simulated tool handle at three different finger grip force levels. Results and Conclusions. The BR is practically independent of the hand coupling actions for frequencies at or above 100 Hz. Above 50 Hz, the BR is correlated to finger and hand sizes. Increasing the finger coupling force significantly increases the BR. Therefore, hand forces should be measured and used when assessing hand-transmitted vibration exposure. The results also show that under a constant-velocity vibration, the finger vibration power absorption at frequencies above 200 Hz is approximately twice that at frequencies below 100 Hz. This suggests that the frequency weighting specified in the current ISO 5349-1 (2001) may underestimate the high frequency effect on vibration-induced finger disorders.

A method to quantify hand-transmitted vibration exposure based on the biodynamic stress concept

2007 ◽  
Vol 221 (8) ◽  
pp. 847-861 ◽  
Author(s):  
R G Dong ◽  
D E Welcome ◽  
J Z Wu
Keyword(s):  
Experimental Data ◽  
High Frequency ◽  
Practical Method ◽  
The Other ◽  
Equivalent Model ◽  
Frequency Effect ◽  
Vibration Exposure ◽  
Stress Cycle ◽  
Vibration Induced White Finger ◽  
Frequency Weightings

This study generally hypothesized that the vibration-induced biodynamic stress and number of its cycles in a substructure of the hand-arm system play an important role in the development of vibration-induced disorders in the substructure. As the first step to test this hypothesis, the specific aims of this study were to develop a practical method to quantify the biodynamic stress-cycle measure, to compare it with ISO-weighted and unweighted accelerations, and to assess its potential for applications. A mechanical-equivalent model of the system was established using reported experimental data. The model was used to estimate the average stresses in the fingers and palm. The frequency weightings of the stresses in these substructures were derived using the proposed stress-cycle measure. This study found the frequency dependence of the average stress distributed in the fingers is different from that in the palm. Therefore, this study predicted that the frequency dependencies of finger disorders could also be different from those of the disorders in the palm, wrist, and arms. If vibration-induced white finger (VWF) is correlated better with unweighted acceleration than with ISO-weighted acceleration, the biodynamic stress distributed in the fingers is likely to play a more important role in the development of VWF than is the biodynamic stress distributed in the other substructures of the hand-arm system. The results of this study also suggest that the ISO weighting underestimates the high-frequency effect on the finger disorder development but it may provide a reasonable risk assessment of the disorders in the wrist and arm.

scholarly journals Correlation of Index Finger Length (2D) with Height, Weight and BMI in Adult Bangladeshi Male

2017 ◽  
Vol 7 (2) ◽  
pp. 90-94
Author(s):  
Karim Rezwan Hasan ◽  
Shamim Ara ◽  
Fakhrul Amin Mohammad Hasanul Banna
Keyword(s):  
Evolutionary Biology ◽  
Index Finger ◽  
Medical Science ◽  
Human Hand ◽  
Cross Sectional ◽  
Morphological Attributes ◽  
Medical College ◽  
Finger Length ◽  
Positive Correlations ◽  
Male Subjects

Background: Human hand is one of the most versatile parts of the human body which plays an important role in modern medical science and evolutionary biology. By virtue of evolution and genetic arrangements, digital lengths vary from person to person according to age, sex, races, occupation or even environmental influences. It has been found that the digital lengths and their ratios are not same in different sexes and even in both hands of same individual. Specially, index to ring digit lengths and their ratios which already have been proved to represent sexual dimorphism may differ in both hands of an individual and show positive correlations with other morphological attributes like height, weight and BMI.Objectives: To analyze the variation of index finger (2D) length and its correlation with height, weight and BMI in adult Bangladeshi male.Materials and Methods: This cross-sectional analytical study was conducted in the department of Anatomy, Dhaka Medical College, Dhaka from July 2012 to June 2013 on 100 male MBBS students (20?25 years of age). With the help of digital vernier caliper measurements of index finger length (2D) was recorded. Height and weight were measured by the stadiometer and weighing scale respectively. BMI was calculated from height and weight. Pearson’s correlation analysis was done to find out the correlation of index finger length with height, weight and BMI.Results: Significant correlation has been found between the lengths of index fingers (2D) and height (p<0.01), but there was no significant correlation of index finger length with weight and BMI (p>0.05).Conclusion: In this study, we found variation in index finger lengths of both hands of Bangladeshi male subjects, which needs further study and comparison.J Enam Med Col 2017; 7(2): 90-94

Nonword repetition and levels of abstraction in phonological knowledge

2006 ◽  
Vol 27 (4) ◽  
pp. 577-581 ◽  
Author(s):  
Benjamin Munson
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Nonword Repetition ◽  
Chronological Age ◽  
Frequency Effect ◽  
Vocabulary Size ◽  
Levels Of Abstraction ◽  
Opposite Pattern ◽  
The Difference ◽  
Restriction Of Range

Susan Gathercole's Keynote Article (2006) is an impressive summary of the literature on nonword repetition and its relationship to word learning and vocabulary size. When considering research by Mary Beckman, Jan Edwards, and myself, Gathercole speculates that our finding of a stronger relationship between vocabulary measures and repetition accuracy for low-frequency sequences than for high-frequency sequences is due to differences in the range of the two measures. In our work on diphone repetition (e.g., Edwards, Beckman, & Munson, 2004; Munson, Edwards, & Beckman, 2005) we tried to increase the range in our dependent measures by coding errors on a finer grained scale than simple correct/incorrect scoring would allow. Moreover, restriction of range does not appear to be the driving factor in the relationship between vocabulary size and the difference between high- and low-frequency sequence repetition accuracy (what we call the frequency effect) in at least one of our studies (Munson et al., 2005). When the children with the 50 lowest mean accuracy scores for high-frequency sequences were examined, vocabulary size accounted for 10.5% of the variance in the frequency effect beyond what was accounted for by chronological age. When the 50 children with the highest mean accuracy scores for high-frequency sequences were examined (a group in which the range of high-frequency accuracy scores was more compressed, arguably reflecting ceiling effects), an estimate of vocabulary size accounted for only 6.9% of the frequency effect beyond chronological age. The associated β coefficient was significant only at the α<0.08 level. This is the opposite pattern than Gathercole's argument would predict.

Development of a New Fatigue Testing Machine for High Frequency Fatigue Damage Assessment

2013 ◽  
Author(s):  
Naoki Osawa ◽  
Tetsuya Nakamura ◽  
Norio Yamamoto ◽  
Junji Sawamura
Keyword(s):  
High Frequency ◽  
High Speed ◽  
Fatigue Testing ◽  
Low Cost ◽  
Plate Thickness ◽  
Testing Machine ◽  
Fatigue Tests ◽  
Frequency Effect ◽  
Wave Load ◽  
Out Of Plane

A new simple fatigue testing machine, which can carry out fast and low-cost fatigue tests of welded joints subject to wave with high frequency vibration, has been developed. This machine is designed for plate bending type fatigue tests, and wave load is applied by using motors with eccentric mass. Springing vibration is superimposed by attaching an additional vibrator to the test specimen, and whipping vibration is superimposed by an intermittent hammering. Fatigue tests which simulate springing and whipping by a conventional servo-type fatigue testing machines are very expensive and use a large amount of electricity. If one uses these conventional machines, it is difficult to simulate superimposed stress wave forms at high speed, and it takes long hours of testing to examine the high frequency effect. In contrast, it is found that fatigue tests can be carried out in fast, i.e. waves with 10Hz or higher frequency for out-of-plane gusset welded joint specimens with 12mm plate thickness by using the developed machine. The electricity to be used for fatigue tests could be minimal, for example one thousandth of that needed for conventional machines. These results demonstrate the superiority of the developed machine.

Handle Shape Affects the Grip Force Distribution and the Muscle Loadings During Power Grip Tasks

2015 ◽  
Vol 31 (6) ◽  
pp. 430-438 ◽  
Author(s):  
Jérémy Rossi ◽  
Benjamin Goislard De Monsabert ◽  
Eric Berton ◽  
Laurent Vigouroux
Keyword(s):  
Grip Force ◽  
Wrist Joint ◽  
Force Sensor ◽  
Force Distribution ◽  
Muscle Coordination ◽  
Muscle Forces ◽  
Power Grip ◽  
Coordination Strategies ◽  
Hand Model ◽  
Kinematic Measurement

The objectives of this study were to investigate the effect of handle shape on the grip force distribution in the hand and on the muscle forces during maximal power grip tasks. Eleven subjects maximally grasped 3 handles with different external shapes (circular, elliptic, and double-frustum). A handle dynamometer, equipped with both a force sensor and a pressure map, was used to record the forces exerted at the hand/handle interface. The finger and wrist joint postures were also computed from synchronized kinematic measurement. These processed data were then used as input of a biomechanical hand model to estimate muscle forces. The results showed that handle shape influences the maximal grip force, the grip force distribution, and the finger joint postures. Particularly, we observed that the elliptical shape resulted in a 6.6% lower maximal grip force compared with the circular and double-frustum handle. Concomitantly, the estimated muscle forces also varied significantly according to the handle shape, with up to 48% differences for the flexor digitorum superficialis muscle for example. Interestingly, different muscle coordination strategies were observed depending on the handle shape, therefore suggesting a potential influence of these geometrical characteristics on pathological risks such as tendonitis.

Response of Grip Force as Effect of Electrics Power Input at Gripper Actuator of NiTi SM495 Wire

2014 ◽  
Vol 493 ◽  
pp. 564-569
Author(s):  
Tjuk Oerbandono ◽  
Hari Budiarto
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Grip Force ◽  
Electrical Power ◽  
Power Input ◽  
Nickel Titanium ◽  
Robot Arm ◽  
Niti Wire ◽  
Electric Voltage ◽  
Power Grip

Gripper is mechanism that mounted on the end of the robot arm and used to hold an object and move it to a certain position. Generally, classical gripper is equipped with the driving motor (electric, pneumatic, fluid power) to move the gripper mechanism. In this research, the function of driving motor replaced with gripper motor actuators made of Shape Memory Alloys (SMA) of Nickel Titanium (NiTi) wire type SM495. Problem studied is response of grip force of gripper to varied electrics power input that given to the actuator of gripper made of NiTi SM495 wire. This is a real experimental research using parameters electrical power input which is obtained by varying the applied electric voltage 3, 6, 9, 12 Volt and constant electric current 5 A. Linear springs with various springs constants of 0.14 N/mm; 0.49 N/mm; 0.981 N/mm; 1.308 N /mm were used for measuring grip force of gripper. The obtained data then analyzed using statistics (analysis of variance). The results showed that the electrical power which given to the NiTi based actuator significantly influenced the grip force of gripper.Keywords: actuators, electric power, grip force, gripper, Nickel Titanium,Shape Memory Alloys, SM495 wire

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