Design Failure Mode Effect Analysis - Concepts & Practice

define the structure and scope of a product, system, or component in dfm boundary diagram. visualize interfaces and interactions among subsystems and components, using the bicycle example to illustrate decomposition.

Explore boundary diagrams, mapping system boundaries, subsystems, and interfaces with the environment and user, using bicycle and bracket examples to illustrate physical connections and potential failure modes.

Examine the B diagram of a screw adjustable wrench, detailing the fixed jaw, movable jaw, and screw mechanism, and show how user torque translates to jaw movement and load transfer.

Explore the boundary diagram of a scissor jack, detailing lead screw, pins, links, and brackets, and map external interactions with vehicle, user, ground, and load transfer.

Explore the external interfaces of a vehicle seatbelt system inside the body pillar, including physical mounting, load transfer, and electrical interfaces to the safety control unit (seiu).

Relate structure and function with a function tree to cascade customer needs into functional requirements, quantify them, and map inputs, disturbances, and parameters via a p diagram.

Clarify the key terms in function analysis, including function, functional requirement, intended outputs, and unintended outputs, and identify control factors, inputs, disturbances, and design parameters for FMEA.

Define the system’s core function and distinguish functions from functional requirements, then examine non-functional requirements such as safety, durability, reliability, aesthetics, ergonomics, and regulatory and maintenance considerations with real-world examples.

Explain how inputs, control factors (design parameters), and noise factors form the p diagram to produce intended outputs while explaining possible unintended outputs.

Explore how a windshield wiper system maintains clear visibility by decomposing into sub functions: clear obstructions, apply cleaning fluid, and control systems, with actuating mechanisms and washer fluid handling.

Explore the function tree and functional decomposition of a bicycle, breaking mobility into driving, braking, seating, steering, and load-bearing functions with key parameters and specifications.

Define the parameter diagram framework per IAG and VDA standards, outlining inputs, control factors, functions and functional and non-functional requirements leading to the intended output, and identify noise factors.

Present a p diagram for a simple adjustable wrench, listing inputs, outputs, functional and non-functional requirements, and design control factors like torque and jaw geometry.

Explains how a traditional car scissor jack uses a lead screw to convert torque into lifting force, outlining inputs, pie diagram, functional and nonfunctional requirements, and noise factors for FMEA.

Analyze the bicycle's p diagram, detailing how pedal input, rider weight, braking, and steering drive acceleration, braking, and steering, with functional requirements, control factors, non-functional requirements, and system interfaces.

Map system structure with boundary diagrams and p diagrams, perform function analysis to identify functional and non-functional requirements, then analyze failure modes, causes, and effects.

Define failure modes as any degradation or loss of function, contextually graded by application, and consider durability, reliability, ergonomics, aesthetics, regulatory compliance, and safety across primary, secondary, and tertiary functions.

Identify failure modes by examining nonfunctioning, underperforming, intermittent, and degrading functions. Link these outcomes to mechanical phenomena such as cracking, deformation, loosening, freeplay, and jamming to guide design and analysis.

Correlate failure modes with end effects and root causes, and use the fishbowl (okinawan) diagram and designed experiments to identify the primary root cause.

Examine material properties, geometry, tolerances, usage patterns, interfaces, and environmental degradation as domains of underlying root causes, using Avivah analysis to trace to the most fundamental fault.

Explore a root cause analysis for a frame crack, examining material, loading, geometry, environment, and interface as failure domains, and prioritize probable causes through structured analysis.

Explore failure modes and their effects, from complete dysfunction to noise in suspension. Learn how a cracked control arm or noisy suspension bushes create safety hazards and loss of control.

Evaluate risk of failure using severity, occurrence, and detection; assess levels from safety impact to regulatory compliance, primary function loss, secondary function degradation, and annoyance.

Examine grading the severity of failures from 1 to 10, prioritizing safety and regulatory compliance, including worst-case without warning and loss of primary or secondary function.

Design prevention control identifies new failure modes and implements design phase measures to prevent recurrence. Use simulations, structural analysis, and changes in geometry or stiffness to avoid resonance and vibration.

Assess how the occurrence of a potential failure cause links to prior history, testing, and analysis. New designs, carryover systems, and novel applications raise occurrence when data is limited.

Analyze occurrence grading in design failure mode and effect analysis per AIG and VDA standards, detailing levels, prevention controls, and lessons learned from prior designs.

Detect and verify design integrity through physical testing, prototype and lab tests, and experiments that detect failure modes not preventable by analysis.

Assess detection grading by evaluating how well physical tests detect failure modes with proven evaluation methods, sample size, and duty cycle; as testing procedures mature, grading improves toward one.

Master the dfmea preparation process using boundary and parameter diagrams, identify failure modes, assess severity, occurrence, detection, compute the risk priority number, and plan actions across product, system, component levels.

Explore the format of the FMEA document by detailing items, functions, requirements, potential failure modes, effects, causes, controls, occurrence, detection, the RPN, and recommended actions.

Examine the DFMEA bike item by analyzing the drive system—the pedal, chain and sprocket, and rear wheel—as the primary locomotion function and its potential failure modes.

Analyze the bike braking system, including the lever, cables, calipers, pads, and rim, and explore how failures like pad run-out, brake line cuts, or jammed links threaten stopping safety.

Examine the steering system—handlebar, fork, and front wheel—and its directional control, outlining failures such as loss or degradation of steering and causes like jammed bars and deflated tires.

Analyze the bike seating system with dfmea, including seat and mounting components, the function of comfortable seating for the driver, and failure modes from seating loss or insufficiency causing discomfort.

Assign severity ratings to item 1 failure modes on a 1–10 scale, identifying loss of primary function, degradation of primary function, and discomfort, with ratings of 8, 7, and 7.

Assign occurrence ratings to potential failure causes on a one-to-ten scale, based on current design controls and analysis to predict failures and gauge correlation with analysis for mitigation.

Assign detection ratings to failure mechanisms in a design failure mode and effects analysis, guiding decisions by current tests and DNA verification methods, including user profile testing.

complete the DFMEA exercise by assigning severity, occurrence, and detection ratings, brainstorm design prevention and detection controls, and plan analyses and physical testing using the Euphemia worksheet.

Explore dfmea for a screwdriver by building the structure tree and boundary diagram, performing function and p/parameter analyses, and identifying failure modes with severity, occurrence, and detection.

Explore a preliminary dfmea of a screwdriver, detailing tip geometry, wear, and torque transfer failures, and design and detection controls like tolerance studies, sops, and various tests.

Analyze dfmea for screwdriver part 3 to identify bending, torsion, and buckling failure modes, their effects on user safety, and design and testing controls to prevent and detect them.

Explore how a hydraulic steering system uses driver input to provide hydraulic assist to the rack and front wheels, and outline the dfma scope for steering components.

Analyze the steering system's two subsystems—the steering gear set and the steering column set—and how the pinion valve, rack gear, hydraulic cylinder, and the intermediate shaft transfer motion.

Map the boundary diagram for the hydraulic steering system, showing physical interfaces and energy transfer from steering wheel, column, and gear to VLN-connected components.

Examine the function analysis of hydraulic power steering, translating driver input into wheel action, reducing effort, and preserving directional stability, with road feedback and ergonomic, crash-safety, and non-functional considerations.

Unpack the function tree of steering systems, from steering ratio and hydraulic assistance to column and pinion transmission, centering behavior, and crash-related collapse, plus road feel.

Examine the pea diagram parameter diagram for the steering system per the VDA standard, detailing driver and road inputs and primary and secondary functional requirements.

Explore dfmea concepts with a focus on steering system failure modes, including steering column connection loss, gear mesh failure, universal joint binding, and hydraulic lockup, plus design and detection strategies.

Analyze hydraulic power-assisted steering to reduce steering effort and mitigate risks from loss of pressure, leakage, sealing failures, or valve damage.

Assess directional stability by examining steering inconsistency, steering wander, pull, and play, and study oversteer and understeer with design checks like suspension geometry and wheel alignment.

Explore crash safety and road feedback in design failure mode effect analysis, detailing column and shaft collapse risks, failure causes, design checks, crash tests, and elastic analysis for steering feel.

Explore how ergonomic driver control interfaces and dfma analysis address steering wheel location, adjustability, and returnability, reducing driver fatigue and safety risks.