{\displaystyle \sigma _{\mathrm {fracture} }={\sqrt {\frac {E\gamma \rho }{4ar_{o}}}}.} Sharp cracks (small 
  
    
      
        ρ
      
    
    {\displaystyle \rho }
  ) and large defects (large 
  
    
      
        a
      
    
    {\displaystyle a}
  ) both lower the fracture strength of the material. Recently, scientists have discovered supersonic fracture, the phenomenon of crack propagation faster than the speed of sound in a material. This phenomenon was recently also verified by experiment of fracture in rubber-like materials. The basic sequence in a typical brittle fracture is: introduction of a flaw either before or after the material is put in service, slow and stable crack propagation under recurring loading, and sudden rapid failure when the crack reaches critical crack length based on the conditions defined by fracture mechanics. Brittle fracture may be avoided by controlling three primary factors: material fracture toughness (Kc), nominal stress level (σ), and introduced flaw size (a). Residual stresses, temperature, loading rate, and stress concentrations also contribute to brittle fracture by influencing the three primary factors.Under certain conditions, ductile materials can exhibit brittle behavior. Rapid loading, low temperature, and triaxial stress constraint conditions may cause ductile materials to fail without prior deformation.
Additional findings
Additional findings that may be present in HFGS according to the latest research are:
Limited metacarpophalangeal flexion of the thumb or limited ability to oppose the thumb and fifth finger
Hypoplastic thenar eminences
Medial deviation of the great toe (hallux varus), a useful diagnostic sign when present
Small great toenail
Fifth-finger clinodactyly, secondary to a shortened middle phalanx
Short feet
Altered dermatoglyphics of the hands; when present, primarily involving distal placement of the axial triradius, lack of thenar or hypothenar patterning, low arches on the thumbs, thin ulnar loops (deficiency of radial loops and whorls), and a greatly reduced ridge count on the fingersRadiographic findings 

Hypoplasia of the distal phalanx and first metacarpal of the thumbs and great toes
Pointed distal phalanges of the thumb
Lack of normal tufting of the distal phalanges of the great toes
Fusions of the cuneiform bones to other tarsal bones or trapezium-scaphoid fusion of the carpals
Short calcaneus
Occasional bony fusions of the middle and distal phalanges of the second, third, fourth, or fifth toes
Delayed carpal or tarsal maturation
Metacarpophalangeal profile reflecting shortening of the first metacarpal, the first and second phalanges, and the second phalanx of the second and fifth digitsUrogenital Defects
Females may have the following:

Vesicoureteral reflux secondary to ureteric incompetence
Ectopic ureteral orifices
Trigonal hypoplasia
Hypospadiac urethra
Subsymphyseal epispadias
Patulous urethra
Urinary incontinence (related to structural anomalies and weakness of the bladder sphincter muscle)
Small hymenal opening
Various degrees of incomplete Müllerian fusion with or without two cervices or a longitudinal vaginal septumMales may have the following:

Retrograde ejaculation (related to structural anomalies and weakness of the bladder sphincter muscle)

Treatment
References


== External links ==