Cumulative Trauma Disorders/Anthropometry
This packet is intended for use in an introductory Statics course when the concept of force is introduced, but before the concept of moment is introduced. Its centerpiece is a homework design problem in which the students are asked to package twelve small boxes in a way that will minimize the loading on the arms of someone lifting the package. The solution is based on forces exerted by the arms (fingers) on the package when the angles of the arms with the vertical are determined by use of tabulated anthropometric data.
Time for presentation is estimated as 15-20 minutes.
Objectives:
1. To reinforce the concept of the force, as presented in Statics, with a practical example related to the human body.
2. To use anthropometric data and the potential for workers to develop cumulative trauma disorders (CTD) to introduce the students to the need to consider safety and ergonomics in design.
This packet includes the following items:
·
Lecture material
for the instructor
·
Overheads
for use during the lecture
Download the Cumulative Trauma Disorders/Anthropometry packet in a printable Adobe Acrobat Format (pdf). This includes overheads in a ready to use format.
Homework problem solutions, exam problems, and exam solutions are available to qualified recipients. Send an email with request information to Dr. Donald Bloswick.
Cumulative Trauma Disorders/Anthropometry Lecture Outline
I. A bit about design (OVERHEAD 1)
A. In design you develop something that meets a defined need.
B. Often there are many acceptable options.
C. Design is a major engineering (and curriculum) requirement.
D. Distribute the homework problem and explain that it deals with a relatively simple packaging design problem.
II. The issue (OVERHEAD 2)
A. Statics assumptions result in relatively simple, mostly linear equations that are not time-dependent.
B. However, a design must be safe, and requires careful consideration of how People will interact with the product of the design.
C. Ergonomics is the relationship between the worker and the work environment.
D. Ergonomic factors often are non-linear and time-dependent.
E. Bad ergonomic design can be costly because it can lead to accidents, injuries and inefficient operations.
III. The design tools (OVERHEAD 3)
A. Anthropometry is that part of ergonomics that deals with the dimensions of the human body.
B. We use anthropometric data in design. (OVERHEAD 4)
i. This chart is based on data collected by Drillis and Contini.
ii. It shows the relative dimensions of the average human body with respect to a person’s height.
iii. For example, the effective width of an average person’s shoulders is 0.259H, where H is the person’s height.
C. We also must consider the differences in people. (OVERHEAD 5)
i. This chart is based on the work of Pleasant
ii. It shows data for males and females.
iii. What data do you need to extract from this chart to use the previous chart? (Answer: measurement 7. “Stature”, which is the person’s height.)
· In design you develop something that meets a defined need.
· Often there are many acceptable options.
· Design is a major engineering requirement.
THE ISSUE
Statics: Simple, mostly linear equations that are not time-dependent.
Ergonomics:
· The relationship between the worker and the work environment.
· Often non-linear and time-dependent.
Bad ergonomic design can be costly because it can lead to accidents, injuries and inefficient operations
Overhead 3
Anthropometry is that part of ergonomics that deals with the dimensions of the human body.
We use anthropometric data in design.
Overhead 4
RELATIVE DIMENSIONS OF THE AVERAGE HUMAN BODY
Link Length Studies Based on Data by Drillis and Contini
STANDING AND SITTING POSTURE DATA
Anthropometric data tables for a standing and sitting posture based on the work of Pleasant
A BIT ABOUT DESIGN
· In design you develop something that meets a defined need.
· Often there are many acceptable options.
· Design is a major engineering requirement.
Statics: Simple, mostly linear equations that are not time-dependent.
Ergonomics:
· The relationship between the worker and the work environment.
· Often non-linear and time-dependent.
Bad ergonomic design can be costly because it can lead to accidents, injuries and inefficient operations.
Anthropometry is that part of ergonomics that deals with the dimensions of the human body.
We use anthropometric data in design.
RELATIVE DIMENSIONS OF THE AVERAGE HUMAN BODY
Link Length Studies Based on Data by Drillis and Contini
STANDING AND SITTING POSTURE DATA
Anthropometric data tables for a standing and sitting posture based on the work of Pleasant
Your company markets a product, which it packages in boxes that are 8" x 9" on the sides and 5" high. Each box weighs 3 pounds. For bulk packaging it has been decided that 12 boxes should be packaged together as a sales unit. Your boss asked you to suggest a packaging configuration for the 12 boxes with rationale for why you chose it. As an example (not what you should recommend, but a configuration to use in your comparison) she suggested that a bulk package 32" x 27" x 5" as shown in Figure 1 would allow easy stacking. She also said that it is expected that sales clerks and customers will lift and carry the bulk packages as shown in Figure 2 and that the effort will make fatigue of the people handling the packages a significant issue. Draw a free body diagram of the box when lifted. Based on a Statics analysis that considers only the average force in each arm, and the attached anthropometric data, what is your recommendation? Please justify your answer.
The chart in Figure 3 shows average body dimensions related to a person's
height, "H", as shown to the left of the figure. The input is, of
course, a person's height and Figure 4 will help with this. Figure 4 shows
various dimensions for males and females. For example, for adult men, 95% would
be taller than 64.6 inches, but only 5% would be taller than 73.6 inches. The
average man's height is 69.1 inches according to this chart.
In this problem your interest will be in a person's shoulder width dimension (0.259H in Figure 3).
