D40 vs D65

D65 is 1.4 times as stiff as D40. It is 1.4 times as dense. Per unit mass they are about equally stiff (19.7 and 20.56 MJ/kg). Strength: f_m,k = 40 MPa for D40, f_m,k = 65 MPa for D65.

D40 EN 338:2016 D65 EN 338:2016

Side by side

ratio = D65 / D40 · log scale

Property	D40	D65	Unit	Ratio
E₁ Modulus, direction 1	13	18.5	GPa	1.42×
E₂ Modulus, direction 2	0.87	1.23	GPa	1.41×
E₃ Modulus, direction 3	0.87	1.23	GPa	1.41×
G₁₂ Shear modulus 1-2	0.81	1.16	GPa	1.43×
G₁₃ Shear modulus 1-3	0.81	1.16	GPa	1.43×
E₀,₀₅ Modulus parallel to grain, 5 % fractile	10.9	15.5	GPa	1.42×
ρ Density	660	900	kg/m³	1.36×
ρ_k Density, characteristic (5 % fractile)	550	750	kg/m³	1.36×
f_m,k Bending strength	40	65	MPa	1.62×
f_t,0,k Tension parallel to grain	24	39	MPa	1.62×
f_t,90,k Tension perpendicular to grain	0.6	0.6	MPa	1×
f_c,0,k Compression parallel to grain	27	35	MPa	1.3×
f_c,90,k Compression perpendicular to grain	5.5	11.3	MPa	2.05×
f_v,k Shear strength	4.2	5	MPa	1.19×
E/ρ Specific stiffness E/ρ · derived	19.7	20.56	MJ/kg	1.04×
c₀ Bar wave speed √(E/ρ) · derived	4438	4534	m/s	1.02×
f/ρ Specific strength f/ρ · derived	60.61	72.22	kJ/kg	1.19×

Values at the first thickness band or product form of each material (EN 338:2016; EN 338:2016). A minimum and a characteristic value are not the same kind of number — read the ratio as a guide. Each material's page lists every band and every source.