208
CHAPTER 5. COASTAL STRUCTURE MODELS
and Mansard 1982) because model armor units usually are not constructed
from a material that meets the similitude requirements listed in Table 5.1.
Timco (1981) and Timco and Mansard (1982) reported on research undertaken to develop a suitable material for use in manufacturing model armor units that would correctly simulate both density and material strength
properties. In addition to the scaling criteria that should be met, Timco
and Mansard (1982) also listed seven general considerations for the model
material:
1. The model material should be macroscopically homogeneous throughout.
2. Molding the material into unusual shapes should not be
overly difficult.
3. The cast armor units should be easy to remove from the
molds without causing damage.
4. The material should allow quick manufacture of a large
number of armor units.
5. The material should not be overly expensive.
6. The material should not be toxic or corrosive, and it should
not break up into a form that is difficult to remove from
the wave facility.
7. The model material should have good stability in water
over a sufficient time span.
No material compound could be identified that satisfied all the scaling
criteria and all the practical considerations. Timco (1981) stated that the
most prominent mode of breakage was by crack propagation in tension, so
he focused on producing a model material that (1) correctly scaled flexural
strength to simulate fracture, and (2) correctly scaled material density to
simulate hydraulic stability.
Timco’s model material was a mixture of sand, iron ore, plaster-of-Paris,
and water. The material simulated tensile and flexural strengths and also
fracture toughness and density. Mansard (1990) reported that armor units
made of this modeling material can be used in models with length scales
ranging between 1:15 - 1:50 to simulate breaking by tensile cracking and
flexure. Complete details of the mixture and manufacturing procedure are
given in Timco (1981).
The model material did not correctly scale the prototype concrete elastic
modulus, and the consequences of this nonsimilitude were discussed by
Timco (1981). For static and pulsating loads, the model armor units will
bend proportionately more than in the prototype, but this shouldn’t matter
CHAPTER 5. COASTAL STRUCTURE MODELS
and Mansard 1982) because model armor units usually are not constructed
from a material that meets the similitude requirements listed in Table 5.1.
Timco (1981) and Timco and Mansard (1982) reported on research undertaken to develop a suitable material for use in manufacturing model armor units that would correctly simulate both density and material strength
properties. In addition to the scaling criteria that should be met, Timco
and Mansard (1982) also listed seven general considerations for the model
material:
1. The model material should be macroscopically homogeneous throughout.
2. Molding the material into unusual shapes should not be
overly difficult.
3. The cast armor units should be easy to remove from the
molds without causing damage.
4. The material should allow quick manufacture of a large
number of armor units.
5. The material should not be overly expensive.
6. The material should not be toxic or corrosive, and it should
not break up into a form that is difficult to remove from
the wave facility.
7. The model material should have good stability in water
over a sufficient time span.
No material compound could be identified that satisfied all the scaling
criteria and all the practical considerations. Timco (1981) stated that the
most prominent mode of breakage was by crack propagation in tension, so
he focused on producing a model material that (1) correctly scaled flexural
strength to simulate fracture, and (2) correctly scaled material density to
simulate hydraulic stability.
Timco’s model material was a mixture of sand, iron ore, plaster-of-Paris,
and water. The material simulated tensile and flexural strengths and also
fracture toughness and density. Mansard (1990) reported that armor units
made of this modeling material can be used in models with length scales
ranging between 1:15 - 1:50 to simulate breaking by tensile cracking and
flexure. Complete details of the mixture and manufacturing procedure are
given in Timco (1981).
The model material did not correctly scale the prototype concrete elastic
modulus, and the consequences of this nonsimilitude were discussed by
Timco (1981). For static and pulsating loads, the model armor units will
bend proportionately more than in the prototype, but this shouldn’t matter