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app.py

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+# -*- coding: utf-8 -*-
+"""Untitled3.ipynb
+
+Automatically generated by Colab.
+
+Original file is located at
+    https://colab.research.google.com/drive/11sS74P6WlrbXCzSh9_b8ELPTtcfdsz8s
+"""
+
+# -*- coding: utf-8 -*-
+# HW3: Deterministic calculator + LLM explanation (Gradio)
+# Topic: Simply supported beam with center point load (max bending stress & midspan deflection)
+
+import json
+import math
+from dataclasses import dataclass, asdict
+
+import gradio as gr
+import numpy as np
+import pandas as pd
+
+
+LLM_MODEL_ID = "google/flan-t5-small"
+
+try:
+    from transformers import pipeline
+    _llm = pipeline("text2text-generation", model=LLM_MODEL_ID)
+except Exception:
+    _llm = None  # no transformers
+
+# -----------------------------
+
+# -----------------------------
+
+@dataclass
+class BeamInputs:
+    L_m: float              # 跨度（m）
+    P_kN: float             # 中点集中力（kN）
+    E_GPa: float            # 弹性模量（GPa）
+    I_cm4: float            # 截面惯性矩（cm^4）
+    c_cm: float             # 中性轴到受拉/受压边缘距离（cm）- 极纤维距离
+    allowable_MPa: float | None = None  # 允许应力（MPa，可选）
+    yield_MPa: float | None = None      # 屈服强度（MPa，可选）
+    safety_factor: float | None = None  # 安全系数 n（可选）
+
+def _validate(x, lo, hi, name):
+    if not (lo <= x <= hi):
+        raise gr.Error(f"{name} 超出有效范围 [{lo}, {hi}]")
+
+def validate_inputs(inp: BeamInputs):
+    _validate(inp.L_m, 0.5, 50.0, "跨度 L (m)")
+    _validate(inp.P_kN, 0.1, 2000.0, "荷载 P (kN)")
+    _validate(inp.E_GPa, 1.0, 300.0, "弹性模量 E (GPa)")
+    _validate(inp.I_cm4, 1.0, 1e9, "惯性矩 I (cm^4)")
+    _validate(inp.c_cm, 0.01, 200.0, "极纤维距离 c (cm)")
+    if inp.safety_factor is not None:
+        _validate(inp.safety_factor, 1.0, 5.0, "安全系数 n")
+    if inp.allowable_MPa is not None:
+        _validate(inp.allowable_MPa, 1.0, 5000.0, "允许应力 (MPa)")
+    if inp.yield_MPa is not None:
+        _validate(inp.yield_MPa, 10.0, 10000.0, "屈服强度 (MPa)")
+
+def beam_calc(inp: BeamInputs):
+    """
+    Simply supported beam with a centered point load P.
+    M_max = P*L/4
+    sigma_max = M_max * c / I
+    delta_mid = P * L^3 / (48 * E * I)
+    单位处理见下。
+    """
+    validate_inputs(inp)
+
+
+    P_N   = inp.P_kN * 1_000          # kN -> N
+    L     = inp.L_m                   # m
+    E_Pa  = inp.E_GPa * 1e9           # GPa -> Pa
+    I_m4  = inp.I_cm4 * 1e-8          # cm^4 -> m^4  (1 cm = 0.01 m → (0.01)^4 = 1e-8)
+    c_m   = inp.c_cm * 0.01           # cm -> m
+
+
+    M_max_Nm = P_N * L / 4.0
+    sigma_Pa = M_max_Nm * c_m / I_m4
+    sigma_MPa = sigma_Pa / 1e6
+    delta_m  = P_N * (L**3) / (48 * E_Pa * I_m4)
+    delta_mm = delta_m * 1e3
+
+
+    allow = None
+    if inp.allowable_MPa is not None:
+        allow = float(inp.allowable_MPa)
+    elif inp.yield_MPa is not None and inp.safety_factor is not None:
+        allow = float(inp.yield_MPa) / float(inp.safety_factor)
+
+    utilization = (sigma_MPa / allow) if (allow and allow > 0) else None
+    pass_check = (utilization <= 1.0) if utilization is not None else None
+
+    record = {
+        "scope": "Simply supported beam, centered point load; small deflection; linear elastic; prismatic section.",
+        "inputs": {
+            "L_m": inp.L_m,
+            "P_kN": inp.P_kN,
+            "E_GPa": inp.E_GPa,
+            "I_cm4": inp.I_cm4,
+            "c_cm": inp.c_cm,
+            "allowable_MPa": inp.allowable_MPa,
+            "yield_MPa": inp.yield_MPa,
+            "safety_factor": inp.safety_factor,
+        },
+        "units": {
+            "L_m": "m", "P_kN": "kN", "E_GPa": "GPa",
+            "I_cm4": "cm^4", "c_cm": "cm",
+            "sigma_MPa": "MPa", "M_max_kN_m": "kN·m", "delta_mm": "mm",
+        },
+        "formulas": {
+            "M_max": "P*L/4",
+            "sigma_max": "M_max * c / I",
+            "delta_mid": "P * L^3 / (48 * E * I)"
+        },
+        "results": {
+            "M_max_kN_m": M_max_Nm / 1_000.0,  # N·m -> kN·m
+            "sigma_MPa": sigma_MPa,
+            "delta_mm": delta_mm,
+            "allowable_MPa": allow,
+            "utilization": utilization,
+            "pass_check": pass_check
+        },
+        "notes": [
+            "If allowable stress is not provided, pass/fail is left as None.",
+            "For non-rectangular/I-beam sections, user provides I and c (or catalogs)."
+        ]
+    }
+
+    table = pd.DataFrame(
+        {
+            "Quantity": ["M_max", "sigma_max", "delta_mid", "allowable", "utilization", "pass"],
+            "Value": [
+                round(record["results"]["M_max_kN_m"], 4),
+                round(record["results"]["sigma_MPa"], 4),
+                round(record["results"]["delta_mm"], 4),
+                (None if allow is None else round(allow, 4)),
+                (None if utilization is None else round(utilization, 4)),
+                str(pass_check)
+            ],
+            "Unit": ["kN·m", "MPa", "mm", "MPa", "-", "-"]
+        }
+    )
+    return record, table
+
+# -----------------------------
+# 2) LLM
+# -----------------------------
+
+def explain_record(record: dict) -> str:
+    compact = json.dumps(record, ensure_ascii=False)
+    prompt = (
+        "You are an engineering assistant. Explain the beam calculation results clearly for a non-expert.\n"
+        "Use the JSON below. Restate the inputs (with units), show the formulas, plug in numbers, and summarize.\n"
+        "If allowable stress is present, state pass/fail and utilization. Avoid hallucinations; only use given data.\n"
+        f"JSON:\n{compact}\n"
+        "Write 120-200 words. Use bullet points for steps. Keep units."
+    )
+    if _llm is not None:
+        try:
+            out = _llm(prompt, max_new_tokens=220, do_sample=False)[0]["generated_text"]
+            return out
+        except Exception:
+            pass
+
+    r = record["results"]
+    i = record["inputs"]
+    lines = [
+        "### Explanation",
+        f"- Span L = {i['L_m']} m; Center load P = {i['P_kN']} kN.",
+        f"- E = {i['E_GPa']} GPa; I = {i['I_cm4']} cm^4; c = {i['c_cm']} cm.",
+        "- Formulas: M=P·L/4; σ=M·c/I; δ=P·L³/(48·E·I).",
+        f"- Computed: M_max = {r['M_max_kN_m']:.3f} kN·m; σ_max = {r['sigma_MPa']:.3f} MPa; δ_mid = {r['delta_mm']:.3f} mm.",
+    ]
+    if r["allowable_MPa"] is not None:
+        lines.append(f"- Allowable = {r['allowable_MPa']:.3f} MPa; utilization = {r['utilization']:.3f}.")
+        lines.append(f"- Pass/Fail: {r['pass_check']}.")
+    else:
+        lines.append("- No allowable stress provided → pass/fail not evaluated.")
+    return "\n".join(lines)
+
+# -----------------------------
+# 3) Gradio
+# -----------------------------
+
+def run_calc(L_m, P_kN, E_GPa, I_cm4, c_cm, allowable_MPa, yield_MPa, safety_factor):
+
+    allowable = None if (allowable_MPa is None or allowable_MPa == "") else float(allowable_MPa)
+    fy = None if (yield_MPa is None or yield_MPa == "") else float(yield_MPa)
+    n  = None if (safety_factor is None or safety_factor == "") else float(safety_factor)
+
+    inp = BeamInputs(
+        L_m=float(L_m), P_kN=float(P_kN), E_GPa=float(E_GPa),
+        I_cm4=float(I_cm4), c_cm=float(c_cm),
+        allowable_MPa=allowable, yield_MPa=fy, safety_factor=n
+    )
+    rec, table = beam_calc(inp)
+    expl = explain_record(rec)
+    return table, expl, rec
+
+with gr.Blocks() as demo:
+    gr.Markdown("# Simply Supported Beam — Center Load\nDeterministic calculator + LLM explanation (first principles).")
+
+    with gr.Row():
+        with gr.Column():
+            L_m = gr.Slider(0.5, 30.0, value=6.0, step=0.1, label="Span L (m)")
+            P_kN = gr.Slider(0.1, 500.0, value=20.0, step=0.1, label="Center load P (kN)")
+            E_GPa = gr.Slider(10.0, 300.0, value=200.0, step=1.0, label="Elastic modulus E (GPa)")
+            I_cm4 = gr.Number(value=8000.0, label="Second moment of area I (cm^4)")  # 例如 IPE/I型钢量级
+            c_cm = gr.Number(value=15.0, label="Extreme fiber distance c (cm)")
+
+            with gr.Accordion("Optional: Allowables", open=False):
+                allowable_MPa = gr.Number(value=None, label="Allowable stress σ_allow (MPa)")
+                yield_MPa = gr.Number(value=None, label="Yield strength fy (MPa)")
+                safety_factor = gr.Number(value=1.5, label="Safety factor n")
+
+            run_btn = gr.Button("Compute")
+
+        with gr.Column():
+            results = gr.Dataframe(headers=["Quantity", "Value", "Unit"], label="Numerical results", wrap=True)
+            explanation = gr.Markdown(label="Explain the results")
+            record_json = gr.JSON(label="Structured record (for LLM)")
+
+    run_btn.click(
+        fn=run_calc,
+        inputs=[L_m, P_kN, E_GPa, I_cm4, c_cm, allowable_MPa, yield_MPa, safety_factor],
+        outputs=[results, explanation, record_json],
+        api_name="run_calc",
+    )
+
+if __name__ == "__main__":
+    demo.launch()

requirements.txt

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+gradio>=4.24
+pandas
+numpy
+transformers>=4.41
+sentencepiece
+accelerate
+huggingface_hub>=0.23