ENG766- ANSYS Geometry Optimisation: Structural Integrity & Optimisation, Assignment - Wrexham Glyndwr University

Optimisation & Fatigue Analysis of a Square Beam Section

Structural optimisation involves multiple engineering disciplines, including computational mechanics, mathematical programming & computer science. The theory is highly comprehensive and practical in methods & technology, consequently it is one of the significant developments of modern design methods. Structural optimisation is used in many fields, including aviation, aerospace, machinery, civil engineering, water conservancy, bridge, automobile, railway transportation, ships, warships, light industry, textile, energy, and military industry, to name just some. Engineering design problems should be solved appropriately, simultaneously pursuing better cost indicator of structure, the improvement of structure performances and enhancement on safety. Nonetheless, structural optimisation design should meet the needs of the industrial production based on the accumulation of design experiences. Structural optimisation design is founded on mathematical theory, method, and computer programming technology as well as its modelling technique.

Therefore, this assignment requires the optimisation and fatigue analysis of a square beam section using ANSYS software package. Figure 1 provides a schematic overview of the square bean section with all boundary conditions/constraints. The optimisation requirements are provided in Question B.

Figure 1: Schematic representation of square beam section, with FEA boundary conditions.

NOTE: Software Restrictions as the FEA modelling will be conducted using the ANSYS student version, there are some limitations. The maximum number of nodes for FEA is 30,000, therefore,
please use triangular mesh to maximise element size. Space Claim allows a maximum of 300 faces for a given model (body), therefore, please insure you “Check Geometry” to insure these
limits in ANSYS Space Claim. 

You are required to carry out the following ANSYS optimisation & fatigue analysis using ANSYS:
A. Generate square beam section using appropriate CAD tool and import into ANSYS static structural and conduct a FEA analysis (Structural Steel – use ANSYS material properties), comparing theoretical and numerical values (Normal Stress & Deformation). (This will be used as your benchmark model)

B. Using ANSYS Space Claim, you must define your Design Space and reduce material by using the shell fill option. Conduct a geometric comparison study to attain best optimised designs (min 2 designs), with min member shell size= 2 mm, and the maximum volume removed to be 50%.

C. Validate and compare with original model presenting total mass, normal stress & total deformation. 

D. Conduct a fatigue analysis (Stress-life) on all respective models, with following conditions and present the fatigue sensitivity minimum and maximum base load variation and Biaxiality Indication results:
• Specify a fatigue strength factor (kf) of 0.8
• Select fully reversed loading to create alternating stress cycles
• Select a stress-life fatigue analysis
• Select Von Mises for stress component
• Specify design life of 1e06 cycles for safety factor
• Self-select and specify lower and upper variations (%) for fatigue sensitivity
• Include Biaxiality indication for comparison 

E. Discuss, summarise and conclude your findings for optimisation and fatigue analyses for all numerical models. 

Module outcomes assessed

1. Demonstrate a conceptual knowledge of material allowable and how they are developed.
2. Recognise failure mechanisms in metallic structures and state the suitability of their use in applications.
3. Demonstrate a critical evaluation of structural integrity, fatigue failure, and how design can be used to reduce the effect of cyclic loading, using Finite Element Analysis (FEA) to evaluate sutural optimisation and fatigue analysis.