Why Factor of safety analysis in Solidworks? - Purpose & Use Cases

The Big Idea

What if you could instantly see if your design is safe or risky without endless calculations?

The Scenario

Imagine you have to check if a bridge design is safe by manually calculating stress and strength for every part using paper and calculator.

The Problem

This manual method is slow, prone to mistakes, and hard to update when design changes. You might miss critical weak points or overestimate safety, risking failure or waste.

The Solution

Factor of safety analysis in SolidWorks automates these checks by quickly calculating safety margins for all parts, highlighting risks visually and updating instantly with design changes.

Before vs After

✗ Before

Calculate max stress = Force / Area; Compare with material strength; Repeat for each part.

✓ After

Use SolidWorks FOS tool to run analysis; View color-coded safety factors on model instantly.

What It Enables

You can confidently design safer products faster by seeing exactly where risks are and making informed improvements.

Real Life Example

An engineer designing a car suspension uses factor of safety analysis to ensure parts won't fail under stress, avoiding costly recalls and accidents.

Key Takeaways

Manual safety checks are slow and error-prone.

Factor of safety analysis automates and visualizes risk assessment.

This leads to faster, safer, and more reliable designs.

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