trade-study

name	trade-study
description	Structured skill for conducting engineering trade studies and concept selection
allowed-tools	["Read","Write","Glob","Grep","Bash"]
metadata	{"specialization":"mechanical-engineering","domain":"science","category":"design-development","priority":"medium","phase":7,"tools-libraries":["Decision analysis tools","MATLAB","Spreadsheets"]}

Trade Study Skill

Purpose

The Trade Study skill provides structured capabilities for conducting engineering trade studies and concept selection, enabling systematic evaluation of design alternatives against requirements.

Capabilities

• Trade study framework setup
• Evaluation criteria definition and weighting
• Concept generation support
• Pugh matrix implementation
• Quantitative scoring methods
• Sensitivity analysis
• Decision documentation
• Stakeholder consensus building

Usage Guidelines

Trade Study Framework

Trade Study Types

Type	Application	Complexity
Screening	Eliminate non-viable options	Low
Pugh matrix	Comparative evaluation	Medium
Weighted scoring	Quantitative ranking	Medium
Multi-attribute utility	Complex decisions	High
Optimization	Parameter selection	High

Process Overview

1. Define objectives and scope
2. Establish evaluation criteria
3. Generate alternatives
4. Collect data for each alternative
5. Score alternatives against criteria
6. Analyze results and sensitivity
7. Make recommendation
8. Document decision

Criteria Development

Criteria Categories

Category	Example Criteria
Performance	Power output, efficiency, accuracy
Physical	Size, weight, volume
Cost	Development cost, unit cost, life cycle cost
Schedule	Development time, lead time
Risk	Technical risk, schedule risk, cost risk
Manufacturability	Complexity, process capability
Reliability	MTBF, failure modes, redundancy
Maintainability	Access, service intervals, spares

Criteria Weighting

Methods for weight assignment:

1. Direct assignment
   - Assign percentages directly
   - Total must equal 100%

2. Pairwise comparison
   - Compare each pair of criteria
   - Calculate weights from preferences

3. Swing weighting
   - Consider range of performance
   - Assign weights based on swing importance

4. AHP (Analytic Hierarchy Process)
   - Structured pairwise comparison
   - Consistency check included

Concept Generation

Brainstorming Guidelines

1. Define the function to be achieved
2. Generate alternatives without judgment
3. Consider:
   - Prior art and benchmarks
   - Different technologies
   - Component variations
   - Configuration options
4. Combine and refine ideas
5. Screen for feasibility

Concept Representation

Method	Detail Level	Use
Sketch	Low	Initial brainstorm
Block diagram	Low-Medium	Functional layout
Layout drawing	Medium	Spatial arrangement
CAD model	High	Detailed evaluation

Pugh Matrix Method

Matrix Setup

Pugh Matrix:
- Rows: Evaluation criteria
- Columns: Concept alternatives
- Datum: Baseline or best-known solution
- Scoring: + (better), - (worse), S (same)

| Criteria | Weight | Datum | Alt-A | Alt-B | Alt-C |
|----------|--------|-------|-------|-------|-------|
| Crit 1   | 0.30   | 0     | +     | -     | S     |
| Crit 2   | 0.25   | 0     | S     | +     | +     |
| Crit 3   | 0.20   | 0     | -     | +     | +     |
| Crit 4   | 0.15   | 0     | +     | S     | -     |
| Crit 5   | 0.10   | 0     | S     | +     | S     |

Results Analysis

Calculate for each alternative:
- Sum of positives
- Sum of negatives
- Weighted sum of positives
- Weighted sum of negatives
- Net score

Use results to:
- Eliminate weak concepts
- Identify best features
- Create hybrid concepts
- Iterate evaluation

Weighted Scoring Method

Scoring Scale

Example 5-point scale:
5 = Excellent, exceeds requirements significantly
4 = Good, exceeds requirements
3 = Acceptable, meets requirements
2 = Marginal, partially meets requirements
1 = Poor, does not meet requirements
0 = Unacceptable, disqualifying

Or numerical scale tied to requirements:
Score = (Performance - Threshold) / (Goal - Threshold)

Weighted Score Calculation

Total Score = Sum(Weight_i x Score_i)

Example:
| Criteria | Weight | Alt-A Score | Alt-A Weighted |
|----------|--------|-------------|----------------|
| Crit 1   | 0.30   | 4           | 1.20           |
| Crit 2   | 0.25   | 3           | 0.75           |
| Crit 3   | 0.20   | 5           | 1.00           |
| Crit 4   | 0.15   | 3           | 0.45           |
| Crit 5   | 0.10   | 4           | 0.40           |
| Total    | 1.00   |             | 3.80           |

Sensitivity Analysis

Analysis Methods

1. Weight sensitivity
   - Vary weights +/- 10-20%
   - Identify crossover points
   - Determine robust winner

2. Score sensitivity
   - Vary scores +/- 1 point
   - Consider uncertainty in data
   - Identify close decisions

3. Tornado diagram
   - Show impact of each factor
   - Prioritize data improvement

Decision Documentation

Trade Study Report

Required sections:
1. Executive summary
2. Objectives and scope
3. Evaluation criteria and weights
4. Alternatives description
5. Data sources and assumptions
6. Scoring rationale
7. Results and analysis
8. Sensitivity analysis
9. Recommendation
10. Appendices (detailed data)

Process Integration

• ME-002: Conceptual Design Trade Study

Input Schema

{
  "study_objective": "string",
  "scope": {
    "system": "string",
    "decision_type": "concept|configuration|supplier|technology"
  },
  "requirements": "array of requirement references",
  "alternatives": [
    {
      "name": "string",
      "description": "string",
      "data_sources": "array"
    }
  ],
  "stakeholders": "array of reviewers",
  "constraints": {
    "budget": "number",
    "schedule": "string",
    "must_meet": 
  

Output Schema

{
  "trade_study_report": {
    "document_number": "string",
    "revision": "string"
  },
  "criteria": [
    {
      "name": "string",
      "weight": "number",
      "rationale": "string"
    }
  ],
  "results": {
    "scoring_matrix": "2D array",
    "weighted_scores": "array",
    "ranking": "array"
  },
  "sensitivity_analysis": {
    "robust_criteria": "array",
    "sensitive_criteria": "array"
     
  
   
     
     
     
     
  

Best Practices

1. Define clear objectives before starting
2. Include diverse stakeholder perspectives
3. Document all assumptions and data sources
4. Use consistent scoring across alternatives
5. Perform sensitivity analysis on close decisions
6. Get stakeholder buy-in on recommendation

Integration Points

• Connects with Requirements Flowdown for evaluation criteria
• Feeds into CAD Modeling for selected concept
• Supports Design Review for decision documentation
• Integrates with Risk assessment for technical risks