During the inspection of replacement hardware for an industrial engine mount, a technician… — Armed Services Vocational Aptitude Battery (ASVAB)

During the inspection of replacement hardware for an industrial engine mount, a technician examines a hex cap screw embossed with the metric property class designation 10.9 on its head. What do the numbers in this metric property class designation specifically indicate about the bolt's mechanical strength?

A
A nominal tensile strength of $100\text{ MPa}$ and a maximum shear limit of $9\text{ MPa}$
A nominal tensile strength of $1000\text{ MPa}$ with a minimum yield strength of $900\text{ MPa}$ Cevap
C
A core shank diameter of $10\text{ mm}$ combined with a fine thread pitch of $0.9\text{ mm}$
D
A tensile rating of $10,000\text{ psi}$ intended for use with a $9\text{ mm}$ SAE-sized drive socket

Cevap

A nominal tensile strength of

1000\text{ MPa}

with a minimum yield strength of

900\text{ MPa}

The metric property class system uses a two-part decimal number (such as 8.8, 10.9, or 12.9) stamped on the bolt head. The number before the decimal point represents

1/100

of the minimum ultimate tensile strength in megapascals (

10 \times 100 = 1000\text{ MPa}

). The number after the decimal point indicates the yield strength ratio as a decimal multiplier (

0.9

), meaning the bolt begins yielding at

90\%

of its ultimate tensile strength (

0.9 \times 1000 = 900\text{ MPa}

Adım Adım Çözüm

Interpret the whole number preceding the decimal point in the property class designation (10).

Multiplying 10 by

100\text{ MPa}

yields a nominal ultimate tensile strength of

1000\text{ MPa}

In the metric fastener grading standard (ISO 898-1), the number before the decimal represents

1/100

of the nominal tensile strength in megapascals.

Interpret the decimal value following the point (.9).

Multiplying the tensile strength (

1000\text{ MPa}

) by 0.9 yields a minimum yield strength of

900\text{ MPa}

The number after the decimal indicates the ratio of yield strength (or proof stress) to nominal tensile strength (

90\%

or 0.9).

Synthesize the two mechanical values to identify the complete property definition.

The bolt has an ultimate tensile strength of

1000\text{ MPa}

and a minimum yield strength of

900\text{ MPa}

Both values are required to define the mechanical class of the fastener under tensile loading.

Anahtar Kavram

Metric bolt property class decimal designations define tensile strength (

X \times 100\text{ MPa}

) and yield strength ratio (

0.Y \times \text{tensile strength}

Tahmini Süre:1m 30s

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