CPE I flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Factor of safety

Ratio of a material's failure stress to the allowable working stress. It accounts for uncertainty in loads, material properties, analysis methods, and consequences of failure.

Two-force member

A body loaded only at two points with no applied moments. For equilibrium, the forces at both points must be equal, opposite, and collinear along the line joining them.

Beam bending stress

Normal stress from bending equals Mc/I, where M is the bending moment, c the distance from the neutral axis to the extreme fiber, and I the area moment of inertia.

Reynolds number

Dimensionless ratio of inertial to viscous forces, rho times velocity times diameter divided by viscosity. It predicts whether pipe flow is laminar or turbulent.

Bernoulli equation

Along a streamline in steady, incompressible, inviscid flow, pressure head plus velocity head plus elevation head is constant. It trades pressure against speed and height.

Yield strength 0.2% offset

For metals lacking a distinct yield point, draw a line parallel to the elastic slope offset by 0.2% strain; its intersection with the stress-strain curve defines yield strength.

Three-phase real power

Real power in a balanced three-phase circuit equals the square root of three times line-to-line voltage times line current times power factor.

Verification versus validation

Verification asks whether the design meets its stated requirements. Validation asks whether those requirements actually capture the user's real need. Both are required.

Pugh matrix

A concept screening tool scoring alternatives against a datum concept using better, same, or worse marks. It eliminates weak concepts rather than producing final weighted rankings.

Worst-case tolerance stack

Total variation equals the arithmetic sum of individual tolerances. It is conservative and appropriate when parts may assemble at opposing tolerance extremes.

Statistical tolerance stack

Total variation equals the square root of the sum of squared individual tolerances. Valid only when part dimensions are independent, centered, and roughly normally distributed.

RPN in FMEA

Risk priority number equals severity times occurrence times detection, each scored on a defined scale. High-severity failure modes warrant action regardless of the computed number.

Design of experiments

A structured set of runs varying factors together so main effects and interactions can be estimated. Randomization, replication, and blocking protect against confounding.

Critical path

The longest-duration chain of dependent activities through a project network. It determines the shortest possible project duration and has zero total float.

Total float

The amount an activity can be delayed without delaying the project finish. It equals late start minus early start, or late finish minus early finish.

Cost performance index

Earned value divided by actual cost. A value below one means each unit of completed work is costing more than budgeted, indicating a cost overrun.

Schedule performance index

Earned value divided by planned value. A value below one means less work has been completed than planned for the reporting date.

Estimate at completion

Forecast total project cost. Divide budget at completion by cost performance index if current cost efficiency persists; add actual cost to remaining budget if work returns to plan.

Crashing versus fast-tracking

Crashing adds resources to critical-path activities to shorten duration, usually raising cost. Fast-tracking overlaps sequential activities, saving time but increasing rework risk.

Control chart signal

A process is out of statistical control when a point falls beyond a control limit, or when a run of seven consecutive points sits on one side of the centerline.

Process capability Cpk

Cpk equals the smaller of the upper and lower specification distances from the process mean, divided by three sigma. It penalizes processes whose mean is off-center.

Hierarchy of controls

Effectiveness order for hazard control: elimination, substitution, engineering controls, administrative controls, then personal protective equipment. PPE is the least reliable measure.

ISO 9001 scope

An international standard specifying requirements for a quality management system, including documented processes, customer focus, and continual improvement. Certification comes from accredited registrars.

OSHA fatality reporting

US employers must report work-related fatalities to OSHA within eight hours, and in-patient hospitalizations, amputations, or losses of an eye within twenty-four hours.

Root cause analysis

A structured method such as 5 Whys, fishbone diagram, or fault tree analysis that identifies the underlying system cause of a problem rather than its immediate trigger.

Paramount obligation

The engineer's first duty is protecting public health, safety, and welfare. It takes precedence over obligations to clients, employers, and project schedules.

Competence rule

Engineers accept only work they are qualified to perform. If assigned outside their competence, they must disclose the limit and obtain qualified assistance before proceeding.

Conflict of interest

A financial or personal interest that could impair professional judgment. The ethical violation is failing to disclose it, not merely holding the interest.

Sealing engineering work

A licensed engineer signs and seals only documents they prepared or directly supervised. Sealing another's unreviewed work is misconduct in every US licensing jurisdiction.

Whistleblower escalation

Report a serious safety or legal concern internally first, then to the appropriate regulator. Public disclosure is a last resort when those channels fail and harm is imminent.

RACI matrix

A responsibility chart assigning each task exactly one accountable party, at least one responsible party, plus consulted and informed parties. It prevents gaps and duplicated ownership.

Tuckman team stages

Teams progress through forming, storming, norming, performing, and adjourning. Conflict peaks during storming and subsides as roles and working norms are clarified.