Factor of safety analysis in Solidworks - Step-by-Step Guide

Introduction

Factor of safety analysis helps you check if a part or assembly is strong enough to handle expected forces without breaking. It shows how much stronger the design is compared to the maximum expected load.

When you want to ensure a machine part will not fail under normal working conditions

When designing a bridge or structure to confirm it can support expected weights safely

When testing a new product to verify it meets safety standards before manufacturing

When comparing different materials or designs to choose the safest option

When analyzing parts that experience varying loads to find weak points

Steps

Step 1: Open your completed simulation study

- Simulation tab > Study Tree

Your simulation model with results is visible on screen

Step 2: Right-click on the Results folder

- Simulation tab > Study Tree

A context menu appears with result options

Step 3: Select 'Factor of Safety Plot'

- Context menu from Results folder

The Factor of Safety plot appears on the graphics area showing safety levels across the model

Step 4: Adjust the plot settings if needed

- PropertyManager panel on the left

The plot updates with your chosen display options like minimum safety factor or color scale

💡 Set a minimum factor of safety value to highlight areas below your safety threshold

Step 5: Review the color-coded plot

- Graphics area

Areas with low factor of safety are shown in red, indicating potential failure risk

Before vs After

Before

Simulation results show stress distribution but no clear safety margin

After

Factor of Safety plot highlights areas with safety factors below 1.5 in red, showing where design may fail

Settings Reference

Minimum Factor of Safety

📍 PropertyManager panel when Factor of Safety plot is active

Sets the threshold below which areas are highlighted as unsafe

Default: 1.0

Display Style

📍 PropertyManager panel

Controls how the factor of safety values are visually represented

Default: Gradient

Show Legend

📍 PropertyManager panel

Displays a color scale legend to interpret factor of safety values

Default: On

Common Mistakes

Ignoring units when interpreting factor of safety values

Factor of safety is a ratio and unitless, but misunderstanding units can cause confusion

Always remember factor of safety is a ratio comparing strength to load, no units involved

Setting minimum factor of safety too low

This hides risky areas and gives false confidence in the design

Use industry standard safety factors (usually above 1.5) to identify weak spots

Running factor of safety plot before completing stress analysis

The plot depends on accurate stress results to calculate safety factors

Always complete and validate stress simulation before generating factor of safety plot

Summary

Factor of safety analysis shows how much stronger your design is than expected loads

It uses color-coded plots to highlight safe and risky areas on your model

Always set a realistic minimum safety factor and complete stress analysis first

Practice

1. What does the factor of safety (FoS) represent in SolidWorks analysis?

easy

A. The speed at which the simulation runs

B. The total weight of the model

C. The ratio of material strength to the maximum expected stress

D. The number of parts in the assembly

Solution

1. Step 1: Understand the definition of factor of safety

   The factor of safety is a measure comparing how strong a material is versus the stress it will face.

2. Step 2: Relate factor of safety to design safety

   A higher factor of safety means the design is safer because the material can handle more stress than expected.

3. Final Answer:

   The ratio of material strength to the maximum expected stress -> Option C

4. Quick Check:

   FoS = Strength / Stress [OK]

Hint: Remember FoS = strength divided by stress [OK]

Common Mistakes:

• Confusing FoS with weight or speed
• Thinking FoS is the number of parts
• Ignoring the stress in calculation

2. Which of the following is the correct way to interpret a factor of safety value of 1.5 in SolidWorks simulation?

easy

A. The model has 1.5 parts

B. The material can withstand 1.5 times the expected stress

C. The simulation ran 1.5 times faster

D. The material will fail at 1.5 units of stress

Solution

1. Step 1: Understand what a factor of safety value means

   A factor of safety of 1.5 means the material strength is 1.5 times greater than the stress it will experience.

2. Step 2: Interpret the value in context

   This means the design is safe up to 1.5 times the expected load before failure.

3. Final Answer:

   The material can withstand 1.5 times the expected stress -> Option B

4. Quick Check:

   FoS = 1.5 means 1.5x strength [OK]

Hint: FoS > 1 means material stronger than stress [OK]

Common Mistakes:

• Thinking FoS is a stress value
• Confusing speed or parts with FoS
• Assuming FoS less than 1 is safe

3. Given a material strength of 300 MPa and a maximum stress from simulation of 150 MPa, what is the factor of safety?

medium

A. 2

B. 0.5

C. 450

D. 150

Solution

1. Step 1: Identify the formula for factor of safety

   Factor of safety = Material strength / Maximum stress.

2. Step 2: Calculate using given values

   FoS = 300 MPa / 150 MPa = 2.

3. Final Answer:

   2 -> Option A

4. Quick Check:

   300 / 150 = 2 [OK]

Hint: Divide strength by stress to get FoS [OK]

Common Mistakes:

• Multiplying instead of dividing
• Using stress divided by strength
• Confusing units or values

4. A SolidWorks simulation shows a factor of safety less than 1 for a part. What is the most likely cause?

medium

A. Material strength is less than the applied stress

B. Simulation ran too quickly

C. The part has too many features

D. The model is missing a material assignment

Solution

1. Step 1: Understand what FoS less than 1 means

   A factor of safety less than 1 means the stress exceeds the material strength, indicating failure risk.

2. Step 2: Identify the cause from options

   Material strength being less than applied stress directly causes FoS < 1.

3. Final Answer:

   Material strength is less than the applied stress -> Option A

4. Quick Check:

   FoS < 1 means stress > strength [OK]

Hint: FoS < 1 means unsafe: stress > strength [OK]

Common Mistakes:

• Blaming simulation speed
• Thinking number of features affects FoS
• Ignoring material assignment impact

5. You have a part with a factor of safety of 0.8 under current load. To improve safety, you can either increase material strength or reduce load. If increasing strength by 25% is not possible, by what percentage must you reduce the load to achieve a factor of safety of 1.2?

hard

A. 40%

B. 50%

C. 20%

D. 33.3%

Solution

1. Step 1: Understand the relationship between FoS, strength, and load

   FoS = Strength / Load. Strength is fixed, so reducing load increases FoS.

2. Step 2: Calculate required load reduction

   Current FoS = 0.8 = Strength / Load. So Load = Strength / 0.8.
   Desired FoS = 1.2 = Strength / New Load.
   New Load = Strength / 1.2.
   Percentage reduction = ((Old Load - New Load) / Old Load) * 100 = ((Strength/0.8 - Strength/1.2) / (Strength/0.8)) * 100 = ((1/0.8 - 1/1.2) / (1/0.8)) * 100 = ((1.25 - 0.8333) / 1.25) * 100 = (0.4167 / 1.25) * 100 = 33.33%.

3. Final Answer:

   33.3% -> Option D

4. Quick Check:

   Reduce load by 33.3% to raise FoS to 1.2 [OK]

Hint: Use FoS = strength/load and solve for load reduction [OK]

Common Mistakes:

• Trying to increase strength when not allowed
• Calculating percentage incorrectly
• Mixing up load and strength in formula