HFS206 Occupational Biomechanics Assignment Question Papers – SUSS, Singapore

Jan 2024 Question Paper

Question 1

Figure Q1 shows John lifting up one end of a long, heavy metal frame. At the instant when the photograph was taken, John was adopting a half-squat posture with the upper body bending forward. He was using his right hand to pull up the frame, with his left palm facing upwards to support the frame.

Question 1a

Determine if the analyses stated in Questions 1a(i) to 1a(iv) will be suitable to analyze the situation depicted in Figure Q1. For each of the proposed methods, state its suitability for the analysis. If it is suitable, briefly describe any specific considerations required and the type of results that can be achieved. If not, briefly explain the reasons for your decision.

Question 1a(i)
Free-Body Diagram of the entire person.
(4 marks)
Question 1a(ii)
Biomechanical Equilibrium Equation Analysis.
(6 marks)
Question 1a(iii)
NIOSH Lifting Equation.
(6 marks)
Question 1a(iv)
Liberty Mutual Snook Table.
(4 marks)

Question 1b

Use Figure Q1b in Appendix B on page 7 to sketch a Free-Body Diagram (FBD) of John lifting the frame. Clearly illustrate and label all the loadings acting on John. Forces must also be shown in their respective horizontal and vertical components. You may use pens with different colors (except RED) to indicate different forces and/or their constituent components. Since John’s left and right hands are exerting different types of forces on the frame, they should be represented as such in the FBD. State any assumptions clearly.

Do remember to detach and attach your completed Figure Q1b in Appendix B for submission together with the answer booklet.
(15 marks)

Question 1c

You would like to gather more information for biomechanical analysis of the situation presented in Figure Q1.

Question 1c(i)

Describe a suitable method that you will deploy to record John’s posture while he works at the metal fabrication plant. His workplace may be crowded, noisy, filled with hazardous machinery, and plenty of personnel movements. State the reasons for your choice. Where appropriate, use simple sketches for illustrations.
(6 marks)

Question 1c(ii)

Plot an angle-time diagram for the LEFT elbow of John, beginning from picking the metal frame up from the ground, and ending with the frame standing on its end vertically. The frame pivots on one of its ends while being lifted up. State your assumptions clearly.
(10 marks)

Question 2

You have been asked to investigate reports of frequent back injuries in a warehouse. Figure Q2 is a screen grab of surveillance recordings from one of their logistic centers. It shows Tim (person on the left) passing a parcel to Dave who was seen stretching across the pallet truck to receive the package.

Question 2a

You will now conduct a NIOSH Lifting Equation (NLE) analysis of Tim’s lifting task. To simplify the analysis, you are going to assume that he fetches the package from his right (indicated as Location ‘A’ in Figure Q2), and places it on the pallet (Location ‘B’) to his left.

Question 2a(i)

Use the information provided below to calculate the Recommended Weight Limit (RWL) for the origin (Location ‘A’) for Tim. You may also refer to the NLE formula in Appendix A on page 6.

• Location ‘A’ is:
  • 140 cm from the floor
  • 60 cm from mid-point between Tim’s ankles
  • Tim needs to twist 60° to reach this point
• Location ‘B’ is:
  • 15 cm from the floor
  • 45 cm from mid-point between Tim’s ankles
  • Tim needs to twist 35° to reach this point
• No built-in handles on the boxes
• Frequency modifier is estimated to be 0.92 for this task
• Weight of the box being lifted is 12 kg.

(9 marks)

Question 2a(ii)

Use the information provided in Question 2a(i) to calculate the Recommended Weight Limit (RWL) for the destination (Location ‘B’) for Tim.

(6 marks)

Question 2a(iii)

Calculate the Lifting Indices (LI) for Tim’s task. Discuss the meaning of the values.

(6 marks)

Question 2a(iv)

By analysing the results obtained from Questions 2a(i) to 2a(iii), propose TWO (2) interventions that may be taken quickly and effectively to reduce the lifting stress on Tim. The recommended intervention must be based on the calculated findings from above. No marks will be awarded for unsubstantiated suggestions.

(10 marks)

Question 2b

Now, you turn the evaluation to Dave.

Question 2b(i)

Looking at Figure Q2, identify TWO (2) biomechanically undesirable postures that Dave has adopted to carry out the task. Briefly analyse their potential detrimental effects on his musculoskeletal system.

(6 marks)

Question 2b(ii)

Another aspect of your assignment is to provide educational materials to the training department on how best to minimise the recurring back injuries. You intend to produce a poster to demonstrate the high biomechanical loads at the lower back for lifting postures similar to that adopted by Dave in Figure Q2.

Propose a preliminary design of the poster for further discussion with the trainers. Ideally, the poster should be graphics rich, with as few texts as possible. Provide a full-page sketch of the poster. (Hints: [i] begin by exploring a biomechanical analysis of forces to be generated by the erector muscle, [ii] use speech bubbles to present ideas.)

(12 marks)

Appendix:

Appendix A:

NIOSH Lifting Equation (NLE)

The NLE may be expressed as:

RWL = LC * HM * VM * DM * AM * FM * CM

where, HM is 25/H

VM is 1- (0.003 x |V-75|)

DM is 0.82 + (4.5/D)

AM is 1 – (0.0032A)

FM, see Question 2

CM, see table below.

This equation follows the NLE metric unit convention. Its terminology follows the established nomenclature.

Appendix B: To be Detached & Attached to Answer Booklet

Student PI no.: ________________________

Question 1(b)

Figure Q1b

(Note: the lines in this diagram have been deliberately made lighter for the added force vectors to be seen more clearly).

Jan 2023 Question Paper

Question 1

You, a human factors specialist, have been assigned to look into some injury issues at a workplace. Adam, the department head, is new to ergonomics and biomechanics. You planned to give him a quick primer on the subject matter.

Question 1a

As a start, you would like to introduce some basic concepts to him. Briefly explain anthropometry in plain language. (Note: You need to explain in your own words. No marks for statements reproduced from any other sources).

(5 marks)

Question 1b

You then try to use a suitable example from his workplace to explain the basics of biomechanics. Figure Q1 shows Lucy, one of his female workers performing an assembling task.

Figure Q1: Lucy performing an assembling task.

Use this example to answer the following:

Question 1b(i)

Identify, with reasons, the anatomical plane for Lucy’s right hand motion. (Note: You may assume that the handle of the tool, indicated as ‘A’ in Figure Q1, remains parallel to a line joining her shoulders.)

(5 marks)

Question 1b(ii)

Identify another joint motion (different from the plane identified in Question 1b(i) above) in Lucy’s assembling task, and describe the plane of motion for that movement.

(5 marks)

Question 1c

Next, you want to relate to Adam the importance of anthropometry and biomechanics in workstation and workplace designs. Briefly discuss the 2-step approach to ensure that the tasks and situations are both suitable and compatible with the intended users. Use Figure Q1 to illustrate how you can apply the 2-step approach to ensure a good working posture for Lucy.

(8 marks)

Question 1d

Your discussions with Adam subsequently led to the design of hand tools. Briefly discuss ONE (1) biomechanical aspect of hand tool design.

(6 marks)

Question 2

Lifting and handling of patients can potentially lead to musculoskeletal problems if proper precautions are not taken. Unlike most household objects, patients may be awkward to handle.

A bedridden person needs help to change his/her posture on the bed. This is to prevent sustained pressure on vulnerable areas of the tissue, which could lead to pressure sores.

Figure Q2 shows Peter, a helper trying to change Jane’s posture, a 55 kg bedridden person on a low bed at her home.

Figure Q2: Peter lifts Jane up to change her posture.

Question 2a

Discuss the lifting posture and the potential musculoskeletal issues faced by Peter (Figure Q2) in the following areas:

Question 2a(i)

Joints of his upper limbs

(5 marks)

Question 2a(ii)

Vertebral column

(4 marks)

Question 2b

Although both the shoulder and hip joints may be viewed as ball-and-socket type, Peter is more likely to suffer from shoulder rather than hip disorders in this activity. Explain why this is so from the anatomical and biomechanical perspectives. (Note: You may use simple sketches of the joints to aid your explanations.)

(8 marks)

Question 2c

For this analysis, you may consider Jane to be lying at the centre of the 120 cm wide bed (Figure Q2), with Peter’s both shins pressing against the edge of the bed. The top surface of the mattress is 35 cm from the ground. Analyse the situation using the NIOSH Lifting Equation (NLE). Other relevant NLE parameters are given in Appendix A on page 6.

Question 2c(i)

For Peter to perform a particular posture changing manoeuvre properly, he needs to lift Jane completely off the mattress. Calculate the recommended weight limit for this lifting activity. Discuss the significance of the result. State your assumptions clearly.

(12 marks)

Question 2c(ii)

You need to reduce the biomechanical stress on Peter by making minor changes to his working situation, but without additional lifting devices. Propose appropriate approaches and modifications. Provide the exact dimensional changes you would recommend. Use NLE to verify the improved lifting conditions.

(15 marks)

Question 3

This question refers to the case study described in Question 2. You are strongly advised to attempt Question 2 first.

It is rather abstract to use NLE to describe how one could improve the biomechanical conditions of an activity. It does not provide good visual cues on the potential ways to improve the situation.

Question 3a

Explain the concept of force equilibrium. Use appropriate diagrams to illustrate your points. You may confine your explanation to static equilibrium.

(4 marks)

Question 3b

Looking back at Figure Q2, use the concept of balancing of forces and moments to discuss the large biomechanical stresses at Peter’s lower back due to his poor lifting posture. Clearly indicate the following in a diagram showing the side-view of his lifting task:

• Fulcrum
• Weights and loads
• Moment arms

(8 marks)

Question 3c

Sketch a free body diagram of Peter lifting Jane. Use Figure Q3(c) provided in Appendix B on page 7 to indicate the vertical and horizontal components of all the external loadings on Peter. You may assume the following:

• The weight of Jane is equally distributed between Peter’s hands.
• Ground reaction forces on Peter are equally distributed between his legs.
• Centre of gravity of Peter is mid-point between his shoulder and hip.
• Edge of bed exert point contacts with Peter’s shins.
• No part of Jane is touching the mattress.
• Since it is assumed that the forces on Peter are symmetrical on the left and right sides of his body, you only need to indicate the forces on one side of his body.

(15 marks)

Appendix A: NIOSH Lifting Equation (NLE)

The NLE may be expressed as:

RWL = LC * HM * VM * DM * AM * FM * CM

where, HM is 25/H

VM is 1- (0.003 x |V-75|)

DM is 0.82 + (4.5/D)

AM is 1 – (0.0032A)

This equation follows the NLE metric unit convention. Its terminology follows the established nomenclature.

For application to Question 2, you may assume the following:

• Distance moved = 50 cm vertically
• Frequency Multiplier = 1.0
• Coupling Multiplier = 0.9

Appendix B: To be Detached & Attached to Answer Booklet

Student PI no.: ________________________

Question 3(c)

Figure Q3(c)

Jan 2022 Question Paper

Case Description (for all questions in this paper)

Read this case description carefully before attempting the questions in this paper.

Two siblings run a busy stall selling steamed buns. Their kitchen is a small area behind the sales counter. To ensure that the buns can be produced quickly, they have constructed a simple yet effective steamer that can handle 20 trays of buns at a time. Figure Q1 shows Tommy (the elder brother) lifting a tray of pre-cooked buns from the floor. He then twists his body towards Jimmy (the younger brother) who is standing on a bench. Due to a previous injury, Jimmy is unable to bend his back and can only stand upright with his knees fully extended to receive the trays from Tommy.

For this case study, you may assume:

• each tray of buns, including the metal container, weighs approximately 15 kg
• diameter of tray is 95 cm
• the wooden tray handle has a diameter of 30 mm, situated at a height of 10 cm from the bottom of the tray
• height of bench is 1 metre
• similar horizontal distance of 55 cm at both the Origin and Destination of the lift
• Tommy would face the tray when lifting it from the floor, then twists his body 90° to his left towards Jimmy
• Frequency Multiplier of Tommy’s lifting task is 0.84
• Tommy is represented by the 5th percentile anthropometric profile as shown in Table Q1 in Appendix A on page 7
• Jimmy is taller at 95th percentile

Figure Q1

Question 1a

Determine the height that Tommy needs to lift the tray of buns. Show the steps of your calculations clearly. State any assumptions you made. (Hint: make use of Table Q1 in Appendix A on page 7.)

(6 marks)

Question 1b

Use the NIOSH Lifting Equation (NLE, see Appendix B on page 8) to analyse Tommy’s lifting action at the beginning of the task. Show clearly (including raw data and detailed calculations) the various multipliers and the Recommended Weight Limit (RWL) at the Origin.

(15 marks)

Question 1c

Determine the corresponding RWL at the Destination. Assume Tommy remains stationary while performing the lifting task.

(12 marks)

Question 1d

Discuss the significance of the Lifting Indices for Tommy’s lifting task, at both the Origin and Destination.

(6 marks)

Question 1e

Illustrate to Tommy how his lifting task can have a severe effect on his musculoskeletal system. Explain in simple English.

(6 marks)

Question 1f

Propose a method to quickly record Tommy’s task at the kitchen so that you can start redesigning a more suitable setup for the siblings.

(5 marks)

Question 2a

Use the human anatomical system to illustrate how a work-related musculoskeletal disorder (WRMSD) may occur at the beginning of Tommy’s lifting task. Identify Tommy’s potential WRMSD.

(5 marks)

Question 2b

Explain the potential musculoskeletal issues that Tommy may encounter at the end of his lifting task.

(5 marks)

Question 2c

Discuss in detail if hand tools could reduce the potential WRMSDs described in Question 2(a) and 2(b) for Tommy.

(10 marks)

Question 3a

Conduct a biomechanical analysis of Tommy’s lifting action at the Origin. You may use the information below (in addition to those already given in the case description) in your analysis:

• Tommy weighs 70 kg
• his trunk (torso, head and neck) is 60% of the body weight, acting at a distance of A cm from L5/S1
• each of his upper limb is 5% of the body weight, acting at a distance of B cm from L5/S1
• weight of the partially filled tray is 10 kg
• centre of the tray is 100 cm from L5/S1
• erector muscle is 5 cm from L5/S1.

Determine the erector muscle force at Origin (Fmo) in terms of the distances A and B. State any assumptions clearly. Show detailed steps of your analysis. You may express the body weight and Fmo in kg. (Hint: develop an equation similar to Fmo = function of A + function of B.)

(15 marks)

Question 3b

Sketch in Figure Q3 (given in Appendix C on page 9) a free body diagram to illustrate the forces experienced by Tommy at the Destination of his lifting task. (Note: To simplify the analysis, Tommy’s body rotation has been ignored and is shown as neutral in Figure Q3.)

(15 marks)

Appendix:

Appendix A: Anthropometric Data

Table Q1

Appendix B: NIOSH Lifting Equation (NLE)

The NLE may be expressed as: RWL = LC * HM * VM * DM * AM * FM * CM

where, HM is 25/H

VM is 1- (0.003 x |V-75|)

DM is 0.82 + (4.5/D)

AM is 1 – (0.0032A)

FM, see Question 1

CM, see table below.

This equation follows the NLE metric unit convention. Its terminology follows the established nomenclature.

Appendix C: Figure Q3 for Question 3(b).

Figure Q3

Sep 2013 Question Paper

Question 1

(a) Create a sketch of the structures of the wrist joint.
(10 marks)
(b) Describe the muscle functions associated with lifting a box from the floor to a table top.
(10 marks)

Question 2

(a) Construct a free body diagram to estimate the forces associated with pushing a hand cart.
(10 marks)
(b) Apply the principles of momentum to the analysis of a pedestrian – car
accident.
(10 marks)

Question 3

(a) Develop a checklist for manual materials handling analysis.
(10 marks)
(b) Explain how the Snook tables were developed.
(10 marks)

Question 4

(a) Explain the anthropometric principles of chair design.
(10 marks)
(b) Compare and contrast tasks with static and dynamic workload.
(10 marks)

Question 5

(a) Outline the procedures for measuring pinch grip strength.
(10 marks)
(b) How would you evaluate hand dexterity?
(10 marks)