#222060 : Finite Element Analysis of a Clamp Frame
PART 1 INITIAL STRESS ANALYSIS
Analysis Model is prepared with the dimension as shown in Fig.1-1
Fig.1-1 Initial Specification
Material propertie as shown in Table1-1 is adopted in the model.
All the degree of freedom is fixed at the lower platform, as shown in Fig.1-2;
Fig.1-2 Boundary Condition at the Lower Platform
Upward axial force (15000N) is applied on the inner surface of the cylindrical hole, as shown in Fig.1-3;
Fig.1-3 Axial Force at the Cylindrical Hole
Mesh is created with a default size, as shown in Fig.1-4;
Fig.1-4 Mesh with a Default Size : 12481 Nodes / 7372 Elements
After the calculation, the following results are obtained;
1. A Stress Plot of the von Mises Stress for the entire frame, clearly showing the area of highest stress.
Fig.1-5 Von Mises Stress : Max. Stress = 204.382(Mpa)
2. A plot of the resultant displacement URES.
Fig.1-6 Displacement : Max. Displacement = 2.000(mm)
3. A Design Check Plot showing the Factor of safety distribution based on Max von Mises stress and using a stress limit of Yield stress, (See Note 2).
Fig.1-7 Factor of Saefty : Min. FOS = 1.21
4. Obtain a print out of the mass of the G-clamp frame in kg to three decimal places (See Note 6).
Fig.1-8 Mass Properties
5. For a clamping force of 15 kN produce a table stating the maximum von Mises stress, the minimum factor of safety, the maximum deflection, and the stiffness of the G-clamp frame.
Table1-2 Calculated Resultant
6. Based on the results of your FEA design checks, carry out hand calculations to estimate the maximum clamping force which could be safely applied using the G-clamp frame without risk of it failing. Describe how you estimated this maximum safe clamping force giving details of any calculations you carried out.
Because the Min. FOS=1.21, there is 21(%) margin of strength, which allows the structure 21(%) more load.
PART 2 VERIFICATION CHECKS (15%)
7. Carry out hand calculations to determine the stresses in the G-clamp frame at section AA. Carry out further hand calculations to find the principal stresses at the location and determine the minimum factor of safety at section AA by hand calculation, using the von Mises distortion energy failure theory. Compare your results with the FEA solution for von Mises stress and comment.
e : Distance between the center of the section A-A and the Force (=0.14m)
M : Bending moment acting the corner of the clamp
I : Moment of Inertia of Area at the section A-A
On the section A-A, the shear stress might be diminished, due to the symmetric situation.
PART 3 INVESTIGATION OF POSSIBLE IMPROVEMENT (25%)
Keeping X = 110mm and Y = 250mm unchanged, the corner shape is modified by filleting with 50(mm), as
shown in Fig.3-1:
Fig.3-1 Finall Specification
8. Repeat the work of PART 1 items 1 to 5 for your final design for the improved G-clamp frame using a clamping force of 15kN and produce the same plots and mass print-out.
1. A Stress Plot of the von Mises Stress for the entire frame, clearly showing the area of highest stress.
Fig.3-2 Von Mises Stress : Max. Stress = 166.352(Mpa)
2. A plot of the resultant displacement URES.
Fig.3-3 Displacement : Max. Displacement = 1.798(mm)
3. A Design Check Plot showing the Factor of safety distribution based on Max von Mises stress and using a stress limit of Yield stress, (See Note 2).
Fig.3-4 Factor of Saefty : Min. FOS = 1.49
4. Obtain a print out of the mass of the G-clamp frame in kg to three decimal places (See Note 6).
Fig.3-5 Mass Properties
5. For a clamping force of 15 kN produce a table stating the maximum von Mises stress, the minimum factor of safety, the maximum deflection, and the stiffness of the G-clamp frame.
Table3-2 Calculated Resultant
Produce a clear table stating the maximum von Mises stress, the minimum factor of safety, the maximum deflection, the stiffness and the mass of the improved G-clamp frame. State the percentage improvements in the minimum factor of safety and stiffness you have achieved together with the percentage reduction in mass of the G-clamp frame.
Table3-3 Improvement
9. Based on the results of your FEA design checks, repeat the hand calculations of item 6 giving full details, and estimate the maximum safe clamping force which could be applied using your improved G-clamp frame without risk of it failing.
Because the Min. FOS=1.49, there is 49(%) margin of strength, which allows the structure 49(%) more load.
PART 4 FINAL DESIGN (10%)
10. Provide a readable electronic copy of the .SLDPRT file for your own unique final design for the improved G-clamp frame.
PART 5 REPORT (30%)
11. Using your own words and sketches if necessary, provide a report describing the changes you made to the G-clamp frame and their engineering basis, and, by referring to your results for clamping load, stiffness and reduction in mass of the G-clamp frame, quantify the improvements in structural efficiency which you have achieved. Your report should contain the plots, mass print-outs, hand calculations and tables requested in PARTS 1, 2 and 3 and should be entirely in your own words. There should be no need for you to download large tracts of material from websites. No credit will be given for such material.
In the structure of this type (Rahmen ), the bending stiffness is a dominant part of the whole structure.
Therefore, the clamp force can be improved, as the Moment of Inertia of Area at the section A-A becomes
larger, at the cost of weight increase.
Whereas, the stress concentration at the corner has much more effect on the clamp capacity than the bending stiffness, which leads to the basic design change at this region.
In other words, the fillet with 50(mm) radius at the corner moderates the sudden shape change, which also
moderates the stress concentration. Moreover, the fillet also reduces its weight.
Because of the design change at the corner, the maximum von Mises stress reduces by 18.6(%), the facter of safety increases by 23(%), the weight reduces by 10.1(%), and the stiffness increases by 11.2(%).
Because of the increase of FOS, the clamp force could increase up to 22.35(kN).
