Problem 12.41 - 3D Mohr’s Circle

[Problem adapted from © Chris Galitz CC BY NC-SA 4.0]

#| standalone: true
#| viewerHeight: 600
#| components: [viewer]

from shiny import App, render, ui, reactive
import random
import asyncio
import io
import math
import string
from datetime import datetime
from pathlib import Path

def generate_random_letters(length):
    # Generate a random string of letters of specified length
    return "".join(random.choice(string.ascii_lowercase) for _ in range(length))

problem_ID = "688"
sigmax = reactive.Value("__")
sigmay = reactive.Value("__")
tauxy = reactive.Value("__")
attempts = ["Timestamp,Attempt,Answer1,Answer2,Answer3,Answer4,Feedback\n"]

app_ui = ui.page_fluid(
    ui.markdown("**Please enter your ID number from your instructor and click to generate your problem**"),
    ui.input_text("ID", "", placeholder="Enter ID Number Here"),
    ui.input_action_button("generate_problem", "Generate Problem", class_="btn-primary"),
    ui.markdown("**Problem Statement**"),
    ui.output_ui("ui_problem_statement"),
    ui.input_text("answer1", "Your Answer 1 in units of MPa", placeholder="Please enter your answer 1"),
    ui.input_text("answer2", "Your Answer 2 in units of MPa", placeholder="Please enter your answer 2"),
    ui.input_text("answer3", "Your Answer 3 in units of MPa", placeholder="Please enter your answer 3"),
    ui.input_text("answer4", "Your Answer 4 in units of MPa", placeholder="Please enter your answer 4"),

    ui.input_action_button("submit", "Submit Answers", class_="btn-primary"),
    ui.download_button("download", "Download File to Submit", class_="btn-success"),
)

def server(input, output, session):
    # Initialize a counter for attempts
    attempt_counter = reactive.Value(0)

    @output
    @render.ui
    def ui_problem_statement():
        return [
            ui.markdown(
                f"A state of plane stress is shown, where σ<sub>x</sub> = {sigmax()} MPa, σ<sub>y</sub> = {sigmay()} MPa, and τ<sub>xy</sub> = {tauxy()} MPa. Use Mohr's circle to determine the principal stresses, the maximum in-plane shear stress, and the maximum absolute shear stress."
            )
        ]

    @reactive.Effect
    @reactive.event(input.generate_problem)
    def randomize_vars():
        random.seed(input.ID())
        sigmax.set(random.randrange(250,750,1))
        sigmay.set(random.randrange(250,750,1))
        tauxy.set(random.randrange(200,500,1))
        
    @reactive.Effect
    @reactive.event(input.submit)
    def _():
        attempt_counter.set(
            attempt_counter() + 1
        )  # Increment the attempt counter on each submission.

        # Calculate the instructor's answer and determine if the user's answer is correct.
        sigmaavg=(sigmax()+sigmay())/2
        R=math.sqrt(tauxy()**2+(sigmax()-sigmaavg)**2)
        instr1 = sigmaavg+R
        instr2 = sigmaavg-R
        instr3= R
        instr4= instr1/2

        correct1 = math.isclose(float(input.answer1()), instr1, rel_tol=0.01)
        correct2 = math.isclose(float(input.answer2()), instr2, rel_tol=0.01)
        correct3 = math.isclose(float(input.answer3()), instr3, rel_tol=0.01)
        correct4 = math.isclose(float(input.answer4()), instr4, rel_tol=0.01)
        
        if correct1 and correct2 and correct3 and correct4:
            check = "All answers are correct."
        else:
            conditions = []
            for i, correct in enumerate([correct1, correct2, correct3, correct4], start=1):
                if correct:
                    conditions.append(f"correct for answer {i}")
                else:
                    conditions.append(f"incorrect for answer {i}")
            check = "; ".join(conditions) + "."
        
        correct_indicator = "JL" if correct1 and correct2 and correct3 and correct4 else "JG"

        random_start = generate_random_letters(4)
        random_middle = generate_random_letters(4)
        random_end = generate_random_letters(4)
        encoded_attempt = f"{random_start}{problem_ID}-{random_middle}{attempt_counter()}{correct_indicator}-{random_end}{input.ID()}"

        session.encoded_attempt = reactive.Value(encoded_attempt)
        attempts.append(f"{datetime.now()}, {attempt_counter()}, {input.answer1()}, {input.answer2()}, {check}\n")

        feedback = ui.markdown(f"Your answers of {input.answer1()}, {input.answer2()}, {input.answer3()}, and {input.answer4()} are {check} For reference in debugging this, the calculated instructor answers are {instr1}, {instr2}, {instr3}, and {instr4}")
        m = ui.modal(feedback, title="Feedback", easy_close=True)
        ui.modal_show(m)

    @session.download(filename=lambda: f"Problem_Log-{problem_ID}-{input.ID()}.csv")
    async def download():
        final_encoded = session.encoded_attempt() if session.encoded_attempt is not None else "No attempts"
        yield f"{final_encoded}\n\n"
        yield "Timestamp,Attempt,Answer1,Answer2,Feedback\n"
        for attempt in attempts[1:]:
            await asyncio.sleep(0.25)
            yield attempt

app = App(app_ui, server)