FE Civil Practice Question Solution included after investigation
CASE E-113 Β· FE

The Bar That Stretched 0.80 mm, Not 0.40

The stress was correct, but only half the member length was used in the deformation equation. The full bar stretched 0.80 mm.

β–Ά INTERACTIVE CASE FILE β€’ 5–10 MIN β€’ CLICK TO INVESTIGATE

Inspect, commit, prove, fix, and sign off.

Case E-113 engineering failure visual
HOW THIS WORKS

Think like
a real engineer.

Follow the investigation process used in the field β€” in five guided steps.

1

Inspect

Review the problem, diagram, and evidence.

2

Commit

Choose your hypothesis.

3

Prove

Run calculations and test your idea.

4

Fix

Select and validate a safe correction.

5

Sign Off

See the full debrief and key takeaways.

Case Brief

SAME PRINCIPLES. HIGHER STANDARDS.
PROBLEM STATEMENT

A steel tie bar carries a constant axial tensile load P=80 kN. It is 2.0 m long, has cross-sectional area A=1000 mmΒ², and elastic modulus E=200 GPa. Determine axial stress, strain, and elongation. A note uses only 1.0 m of length and reports 0.40 mm.

Mechanics Of Materials Civil Design Verification Root Cause Analysis Safe Correction
E-113
INVESTIGATION WORKSPACE WORK THROUGH THE CASE β€” YOUR CHOICES MATTER.
πŸ”’
DEBRIEF (LOCKED)

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to unlock the full debrief.

Find the root cause, confirm the fix, and see how this connects to the exam.

πŸ”’Root causeComplete the case
to reveal
πŸ”’Correct fixComplete the case
to reveal
πŸ”’Exam takeawayComplete the case
to reveal
CASE CLOSED Β· ENGINEERING VERDICT

What actually failed β€” and what should change.

What failed

Only half the member length was used.

What was missed

The entire prismatic bar carries the axial force.

Corrected model

Use Ξ΄=PL/(AE) over the full loaded length.

QUICK ANSWER

Οƒ=80 MPa, Ξ΅=0.0004, and Ξ΄=PL/(AE)=0.80 mm.

ENGINEERING TAKEAWAY

For a uniform prismatic bar under constant axial force, use the full loaded length in Ξ΄=PL/(AE).

CASE QUESTIONS

Questions this case should settle.

What is the elastic axial-deformation formula for a prismatic bar?

Ξ΄=PL/(AE) when axial force, area, and modulus are constant.

NEXT FE PRACTICE QUESTION

The Plate That Peaked at 92.4 MPa, Not 110

Mechanics Of Materials Β· 5–10 min

Continue Practice β†’
WHAT YOU’LL LEARN

Real failures. Lasting skills.

Each case is designed to build the judgment, analysis, and confidence you need for engineering exams β€” and beyond.

  • Apply core engineering concepts to real-world problems
  • Practice structured troubleshooting and analysis
  • Strengthen exam-ready thinking through realistic scenarios
COMMON QUESTIONS
Do I need prior knowledge to use these cases?

Basic subject familiarity helps, but every case is designed to teach through the investigation itself.

How long does a case take?

Most cases are designed for a focused 5–10 minute investigation.

Are the cases aligned with engineering exams?

Each case is mapped to a verified exam, subject, topic, and misconception before publication.

What happens after I complete a case?

The sealed debrief unlocks with the root cause, corrected reasoning, fix, and takeaway.