', unsafe_allow_html=True)
# --- Main Content ---
# Title
st.title("Biomaterials Stress-Strain Explorer")
# Description Area
st.subheader(f"Material: {selected_material}")
st.info(preset["desc"])
# Screen Reader Description (Hidden visually but readable)
if screen_reader_mode:
st.markdown(f"""
Chart displays stress-strain curve for {selected_material}.
Young's Modulus is {E} MPa.
Yield Strength is {sigma_y} MPa.
Ultimate Tensile Strength is {sigma_uts} MPa.
Fracture occurs at strain {epsilon_break}.
""", unsafe_allow_html=True)
# --- Calculation ---
strain, stress = generate_stress_strain(E, sigma_y, sigma_uts, epsilon_break, preset["type"])
# --- Plotly Chart ---
fig = go.Figure()
# 1. The Stress-Strain Curve
fig.add_trace(go.Scatter(
x=strain,
y=stress,
mode='lines',
name='Stress-Strain',
line=dict(color=preset["color"], width=4),
hovertemplate="Strain: %{x:.3f}
Stress: %{y:.1f} MPa
"
))
# 2. Elastic Modulus Line (Dashed, up to yield)
epsilon_y = sigma_y / E
fig.add_trace(go.Scatter(
x=[0, epsilon_y],
y=[0, sigma_y],
mode='lines',
name='Elastic Modulus',
line=dict(color='red', width=2, dash='dash'),
hoverinfo="skip"
))
# 3. Annotations for Key Points
annotations = []
# Yield Point
annotations.append(dict(
x=epsilon_y, y=sigma_y,
xref="x", yref="y",
text=f"Yield Point
σ={sigma_y} MPa",
showarrow=True, arrowhead=2, arrowsize=1, arrowwidth=2, arrowcolor="orange",
bordercolor="orange", borderwidth=1, borderpad=4, bgcolor="white",
font=dict(family="Arial", size=12, color="orange")
))
# UTS Point
# Find index closest to UTS for accurate annotation placement
uts_idx = np.argmax(stress)
uts_strain = strain[uts_idx]
annotations.append(dict(
x=uts_strain, y=sigma_uts,
xref="x", yref="y",
text=f"UTS
σ={sigma_uts} MPa",
showarrow=True, arrowhead=2, arrowsize=1, arrowwidth=2, arrowcolor="purple",
bordercolor="purple", borderwidth=1, borderpad=4, bgcolor="white",
font=dict(family="Arial", size=12, color="purple")
))
# Fracture Point
annotations.append(dict(
x=epsilon_break, y=0,
xref="x", yref="y",
text=f"Fracture
ε={epsilon_break}",
showarrow=True, arrowhead=2, arrowsize=1, arrowwidth=2, arrowcolor="black",
bordercolor="black", borderwidth=1, borderpad=4, bgcolor="white",
font=dict(family="Arial", size=12, color="black")
))
fig.update_layout(
annotations=annotations,
xaxis_title="Strain (ε) - Dimensionless",
yaxis_title="Stress (σ) - MPa",
title="Stress-Strain Curve",
template="plotly_white" if not high_contrast else "plotly_dark",
hovermode="x unified",
legend=dict(x=0.01, y=0.99, bgcolor="rgba(255,255,255,0.8)"),
margin=dict(l=50, r=50, t=50, b=50)
)
# Accessibility: If high contrast, force dark background on plot
if high_contrast:
fig.update_layout(paper_bgcolor="black", plot_bgcolor="black")
fig.update_xaxes(gridcolor="gray", zerolinecolor="white", tickfont=dict(color="white"))
fig.update_yaxes(gridcolor="gray", zerolinecolor="white", tickfont=dict(color="white"))
st.plotly_chart(fig, use_container_width=True)
# --- Data Table (For Accessibility/Reference) ---
st.subheader("📋 Key Mechanical Properties")
df_props = pd.DataFrame({
"Property": ["Young's Modulus", "Yield Strength", "Ultimate Tensile Strength", "Strain at Break", "Yield Strain", "Toughness (Approx)"],
"Value": [
f"{E} MPa",
f"{sigma_y} MPa",
f"{sigma_uts} MPa",
f"{epsilon_break}",
f"{epsilon_y:.4f}",
f"{np.trapezoid(stress, strain):.1f} MJ/m³"
],
"Description": [
"Stiffness in elastic region",
"Onset of plastic deformation",
"Maximum stress before necking",
"Strain at fracture",
"Calculated as σ_y / E",
"Area under curve (Energy absorbed)"
]
})
st.dataframe(df_props, use_container_width=True, hide_index=True)
# Close the div if we opened it for CSS classes
if css_classes:
st.markdown("