Reference no: EM13870194

Problem 1:

A critical problem was identified in modified dump truck buckets (by a local company) working in an open cut mine. The problem was mainly caused by over loading the buckets with loading debris falling on the forward protruding canopy as a result of the loading operation. Fatigue cracks were found on the front canopy walls as shown in the Figure 1(a). Excessive deflection of front canopy was also observed. An engineer was assigned to investigate this problems and the following information was provided to him.

• Bucket dimensions and specifications (Some measurements of the bucket's components supplied by the site's Mechanical Forman)
• Due to un-even road surfaces it is assumed that bucket is experiencing impact forces frequently on front canopy wall and the side walls.
• Dump trucks also are experiencing 1.5 g horizontal impact loads frequently due to sudden application of brakes over uneven roads.
• Average load in the bucket is 80 metric tonnes. It is estimated that about 80% of the total weight force acts on the front wall of the bucket in a 1.5g braking event (evenly spread on the front inclined canopy wall)
• Buckets are fabricated with 20 mm AS300 Grade structural steel sheets.
• Canopy loads can be taken as 2.0 tonnes (evenly spread).

Assuming you were that engineer;

1. Create a suitable FEA model (Full or Half) for the Dump Truck Bucket on Creo2.0 and perform following tasks.

• You should try to use the given dimensions, specifications and operational details as much as possible.
• Justify your assumptions thoroughly.

2. Perform relevant static analysis and investigate the problematic areas. You need to explain your load cases clearly.

3. Show all necessary stress/strain/displacement fringe plots for the existing configuration.

4. Suggest a modification using only additional stiffeners/tie-plate (gusset plates). Completing your modifications should not take the truck out of service for more than 1 day. (welding etc).

• The modification should not have any adverse effected on the trucks operational capability.

5. Create an FEA (Full or Half) model of the bucket with your modifications and perform static FEA analysis. With the aid of stress/strain/displacement fringe plots, thoroughly describe the benefits of your changes due to your modifications. Also obtain the first two natural
frequencies of the bucket and the mode shapes. Show a plot of mode shape of the bucket at first natural frequency.

6. Explain how your modifications are likely to overcome the frequent fatigue damage.

(Approximate details of the bucket can be found in attached files. Please note that the measurements are not exact and within +/- 100 mm)

(a) Views of modified dump truck bucket showing high stress areas (red circles)

(b) Typical dump truck bucket

Figure1 Representation s of a dump truck bucket (Approx. dimensions are attached)

Problem 2a:

Perform an FEA for functionality of one of the following components. You need to do your own research and determine realistic/actual geometry/dimensions, the functionality/real-life use and the materials for your analysis. The functionality/real-life use must be clearly detailed in your report.

You need to perform a static analysis and either steady state thermal analysis or modal analysis depending on their significance to the functionality. In your report, you must clearly show your estimate of input forces, temperatures etc.

1. A standard bicycle frame.

2. A shaft and propeller assembly of a water cooled automobile engine.

You may use sub-structuring, symmetry as required. 60% of marks will be awarded to description (functionality, operational forces etc), modelling, assumptions and modelling techniques (mesh refinement, appropriate analysis etc.). Rest of the marks will be awarded for results presentation and discussion.

Problem 2b:

Read Section 6 of the Study Book, the Lecture Notes and the reading documents provided for week 8.

A cubic shape function [N] is defined for a beam element shown in Figure 2 (a)

For the beam element shown above: M = EI d²v/dx²

Where v = [N] {d} and K = [B] {d}, {d} ={v1 θ1 v2 θ2}

Using the relationship

your task is to determine the stiffness matrix for a "plane frame element" (which is capable of axial displacement and bending) shown in Figure 4 Show your analysis clearly and neatly.

(b) A beam element

Figure 2 (a) Shape function for a beam element (b) A beam element