Materials Selection (EML4542)

Course Description

Materials Selection examines the fundamental relationships that govern the properties of materials and uses this understanding to optimize the selection of engineering materials for given applications. Materials from the broad range of metals, plastics, ceramics, and composites are examined.

Within the SCNS taxonomy, EML is the Mechanical Engineering prefix. The University of West Florida publishes this at 3 semester hours, prerequisite EGN3365, giving approximately 45 contact hours.

Materials selection is a genuinely under-taught engineering skill. Most curricula teach materials science — why materials behave as they do — and mechanics teaches how to analyze a chosen material. Almost nothing teaches how to choose, and yet material selection determines cost, weight, manufacturability, durability, and environmental impact simultaneously. This course supplies a systematic method for a decision most engineers make by habit or by copying the last design.

Learning Outcomes

Required Outcomes

• Describe the structure-property relationships governing engineering materials.
• Describe the principal classes of materials and their characteristic property ranges.
• Describe metals, their alloy families, and their strengthening mechanisms.
• Describe polymers, their structures, and their thermal and mechanical behaviour.
• Describe ceramics and glasses and their characteristic brittleness.
• Describe composites and hybrid materials and their design freedom.
• Interpret material property charts and identify property clusters and limits.
• Translate a design requirement into function, objective, constraints, and free variables.
• Derive material indices for common loading and geometry cases.
• Apply material indices to screen and rank candidate materials.
• Apply property charts with index lines to select materials graphically.
• Perform multi-objective selection and describe trade-off surfaces.
• Apply penalty functions and exchange constants to trade cost against performance.
• Account for manufacturing process compatibility in selection.
• Account for shape and section efficiency using shape factors.
• Describe corrosion and environmental degradation and their effect on selection.
• Describe temperature limits and creep in material selection.
• Describe fatigue and fracture considerations in selection.
• Describe cost, availability, and supply risk in material choice.
• Describe recycling, embodied energy, and environmental impact.
• Use materials databases and selection software.
• Document and justify a materials selection decision.
• Perform a case-study selection from requirement through recommendation.

Optional Outcomes

• Describe materials for extreme environments.
• Describe biomaterials and biocompatibility.
• Describe smart and functional materials.
• Describe substitution and material failure case studies.
• Describe life cycle assessment methods.
• Describe additive manufacturing materials and their constraints.

Major Topics

Required Topics

• Structure-property relationships
• Classes of materials and property ranges
• Metals and alloy families
• Polymers
• Ceramics and glasses
• Composites and hybrids
• Material property charts
• Function, objective, constraints, free variables
• Deriving material indices
• Screening and ranking
• Graphical selection with index lines
• Multi-objective selection
• Penalty functions and exchange constants
• Process compatibility
• Shape factors and section efficiency
• Corrosion and degradation
• Temperature and creep
• Fatigue and fracture in selection
• Cost, availability, and supply risk
• Recycling and embodied energy
• Materials databases and software
• Documenting a selection
• Case studies

Optional Topics

• Extreme environment materials
• Biomaterials
• Smart and functional materials
• Substitution and failure case studies
• Life cycle assessment
• Additive manufacturing materials

Resources & Tools

• Materials Selection in Mechanical Design (Michael Ashby) — the book on this subject, and one of the genuinely original engineering texts. The property charts and the index method are his.
• Engineering Materials 1 and 2 (Ashby & Jones) — the underlying materials science, clearly written.
• Materials Science and Engineering: An Introduction (Callister) — the standard reference carried forward from EGN3365.
• CES EduPack / Ansys Granta EduPack — the selection software built around Ashby's method; many institutions license it, and it is the tool the course most likely uses.
• MatWeb — free material property database with thousands of grades.
• Granta and Ashby property charts — reproduced in the text and worth studying until the clusters are familiar.
• Manufacturer and supplier datasheets — free, and the operative source for a real selection.
• ASM Handbook series — the metals reference; institutions normally provide access.
• Excel or Python — for computing indices across a candidate set and plotting your own selection charts.
• NCEES FE Reference Handbook — free; the materials section is examined.

Career Pathways

• Materials engineer — SOC 17-2131; the direct destination.
• Design engineer — SOC 17-2141; material choice is a design decision and this is the systematic method for it.
• Product development engineer — where cost, weight, and performance trade off explicitly.
• Aerospace materials engineer — weight-driven selection is the discipline's defining problem, and Florida's aerospace sector is a direct pathway.
• Corrosion engineer — a distinctly valuable specialization in Florida, where coastal and marine environments make material degradation a routine and expensive problem.
• Failure analysis engineer — many failures are selection failures.
• Manufacturing engineer — process and material choice are inseparable.
• Sustainability and life cycle engineer — a growing function driven by regulation and reporting requirements.
• Supply chain and sourcing engineer — material availability and substitution.
• Technical sales and applications engineering for material suppliers.
• Graduate study in materials science or design.

Special Information

⚠ The material index is the method — learn to derive one

• The Ashby method turns selection from opinion into arithmetic. State the function, the objective to be minimized, the constraints, and the free variables — then eliminate the free variable and what remains is a material index combining properties.
• The index depends on the loading and the geometry, not just the objective. A light stiff tie, a light stiff beam, and a light stiff panel have different indices — and that result surprises students who expect one "best light stiff material."
• Property charts make the answer visible. Plotting an index as a line on a log-log chart and sliding it identifies the winning cluster immediately, which is why the charts are the method's signature.
• Screen on constraints first, then rank on the index. Constraints are absolute — maximum temperature, corrosion resistance, non-magnetic — and no index value rescues a material that fails one.
• Derive indices yourself rather than looking them up. The derivation is short, it is examinable, and it is what lets you handle a case the textbook does not list.
• Multi-objective problems have no single winner. Minimizing both mass and cost produces a trade-off surface, and choosing a point on it requires an exchange constant — an explicit statement of what a kilogram saved is worth. Making that judgement explicit is far better engineering than leaving it implicit.
• Shape matters as much as material. A hollow section outperforms a solid one of the same material and mass, and shape factors let you compare a material-plus-shape combination properly.

⚠ Selection failures are real failures — and Florida corrodes things

• Many engineering failures are selection failures rather than analysis failures: the right calculation performed on the wrong material.
• Corrosion is the dominant environmental degradation mechanism, and it is a specifically severe Florida problem — salt spray, humidity, and warm coastal water attack materials that perform indefinitely inland.
• Galvanic corrosion is a selection error waiting to happen. Two dissimilar metals in electrical contact with an electrolyte corrode preferentially, and in a marine environment the electrolyte is always present. Stainless fasteners in aluminium is the classic case.
• Stainless steel is not stain-proof. Grade matters enormously — 304 pits in chloride environments where 316 survives — and specifying "stainless" without a grade is not a specification.
• Polymers degrade in ultraviolet light, which in Florida is a design consideration rather than a footnote; unstabilized plastics fail outdoors here in a way they do not in northern climates.
• Temperature limits are often the binding constraint, and polymers in particular lose stiffness and strength well below any obvious melting point.
• Creep governs at elevated temperature, and a material adequate for short-term load may deform continuously under sustained load and heat.
• Check the service environment explicitly — it is the constraint students most often omit from a selection exercise, and the one that causes the most real failures.

⚠ Data quality, cost, and the questions selection software will not ask

• Property data scatters and databases give typical values. Design allowables — statistically based minimum values — are a different and much more conservative thing, and safety-critical design uses those.
• Processing changes properties dramatically. The same alloy heat treated differently can differ by a factor of several in strength, so a material is not fully specified without its condition or temper.
• Cost data is volatile. Commodity prices move, and a selection made on last year's prices may be wrong. Rule 11 applies.
• Availability and supply risk are real constraints. A material that is optimal and unobtainable in the required form, size, or lead time is not a solution — and recent years have made supply resilience a mainstream engineering consideration.
• Standard forms constrain choice. Materials come in stock sizes and shapes; specifying something requiring a custom mill run changes the economics entirely.
• Recycled content, embodied energy, and end-of-life are increasingly required considerations, and regulation in this area is expanding.
• Software ranks candidates; it does not decide. Selection tools apply the method faithfully to the constraints you entered — and the constraints you failed to enter are where the error lives. The same warning this repository applies to finite element and computational fluid analysis applies here.
• Document the reasoning. A selection you cannot justify in six months is one nobody can revisit when requirements change.

⚠ An honest account of the workload

• Upper-division mechanical engineering demands sustained daily problem-solving. Budget eight to twelve hours a week outside class.
• Work problems without the solution visible. Reading a worked example produces the feeling of understanding and none of the ability.
• State your assumptions explicitly — knowing which assumptions apply is most of the subject.
• Carry units through every step and check that the answer is physically plausible.
• Go to office hours in week two, not week ten.

⚠ Institutional context — check the number against the description

• This guide is written from the University of West Florida catalog, which publishes a complete and explicit set of EML entries. Other Florida institutions teaching this subject may number it differently.
• The EML prefix is not consistent across Florida. This repository documents a genuine subject collision in the thermal-fluids sequence — EML3015 and EML3016 denote different subjects at UWF and at the FAMU-FSU College of Engineering.
• Much of the mechanical engineering core is also taught under the general engineering prefix EGN, and under SCNS those are different courses. Equivalency does not cross prefixes or a C or L suffix.
• Identify a course by its catalog description, never by its number or title, and give a receiving department the description rather than the number.

⚠ FE exam and PE licensure — this is the accredited engineering pathway

• This course sits inside an A.B.E.T.-EAC accredited engineering programme, the pathway that leads directly to professional licensure — distinct from engineering technology, where the route to a P.E. is longer.
• Florida licenses professional engineers under Chapter 471, Florida Statutes, through the Florida Board of Professional Engineers: A.B.E.T.-EAC degree → FE examination → qualifying experience → PE examination → licensure.
• The NCEES FE Reference Handbook is free and is the only reference permitted in the exam. Use it as your working reference now.
• Only a licensed P.E. may offer engineering services to the public in Florida, seal drawings, or use the title in a way implying licensure.
• Rule 11 applies — verify current requirements with FBPE and NCEES directly.

How Florida course levels affect transfer

The first digit of an SCNS number denotes the year of offering, not transferability. Courses at the 1000 and 2000 levels transfer transparently between Florida public institutions, and 3000 to 4000 is unproblematic since both are upper division. The boundary that actually matters is 2000 to 3000, where lower-division credit generally cannot satisfy an upper-division requirement.

EML4542 is 3 semester hours and approximately 45 contact hours. Expect case-study selection exercises as the dominant assessment — which is the correct format, since the skill is the method rather than a body of facts.

Keep Ashby. It is one of the few undergraduate texts that changes how an engineer thinks rather than merely what they know, and the method applies to every design decision involving a choice among alternatives.